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Information for Teachers, Including Suggestions
on Relevance to School Curricula.
-NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
Produced by theSkylab Program and NASA's Education Programs
Division in Cooperation with the University of Colorado
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
Washington, D.C. 20546, May 1973
For sale by the Saperlntendent of Docnmeots, U.S. QoTemment Printing Office, Washington, D.C. 20402
Characteristically, new scientific knowledge reaches general application in classrooms years
after it has been obtained. This long delay stems, to a large extent, from a lack of awareness
that information is available and that it has relevance to secondary school curricula. To
accelerate this process, the National Aeronautics and Space Administration has prepared a
series of documents concerning Skylab experiments to apprise the educational community
in detail of the investigations being conducted in the Skylab Program, and the types of
information being produced.
The objective is not to introduce the Skylab Program as a' subject in the classroom, but
rather to make certain that the educational community is aware of the information being
generated and that it will be available for use. Readers are urged to use these books as an
aid in planning development of future curriculum supplement materisil to make the most
appropriate use of this source of scientific knowledge.
National Aeronautics and Space Administration
Washington, B.C. 20546
SECTION 1-lNTRODUCTION 1
SECTION 2-MINERAL AND HORMONAL BALANCE 5
Skylab Experiment M071, Mineral Balance 11
Skylab Experiment M073, Bioassay of Body Fluids 13
Skylab Experiment M078, Bone Mineral Measurement 15
SECTION 3-HEMATOLOGY AND IMMUNOLOGY 17
Skylab Experiment Mill, Cytogenic Studies of the Blood 23
Skylab Experiment M112, Man's Immunity, in vitro Aspects 25
Skylab Experiment Ml 13, Blood Volume and Red Cell Life Span 27
Skylab Experiment Ml 14, Red Blood Cell-Metabolism 29
Skylab Experiment Ml 15, Special Hematologic Effect 31
SECTION 4-CARDIOVASCULAR STATUS 35
Skylab Experiment M092, Inflight Lower Body Negative Pressure (LBNP) .... 41
Skylab Experiment M093, Vectorcardiogram 43
SECTION 5-ENERGY EXPENDITURE 47
Skylab Experiment Ml 71, Metabolic Activity 49
SECTION 6-NEUROPHYSIOLOGY 53
Skylab Experiment M131, Human Vestibular Function 53
Skylab Experiment, Sleep Monitoring 59
SECTION 7-BIOLOGY 65
Skylab Experiment SOI 5, Effects of Zero Gravity on Single Human Cells 66
Skylab Experiment S071,Circadian Rhythm— Pocket Mice 69
Circadian Rhythm— Vinegar Gnats 72
SECTION 8-CLASSROOM ACTIVITIES 77
SECTION 9-GLOSSARY OF TERMS 87
The Skylab Education Program
This year the United States' first manned scientific space station, Skylab, was launched into
orbit to be the facility in which successive crews of astronauts can perform more than 270
scientific investigations in a variety of fields of interest. These investigations can be divided
into four categories: physical sciences, biomedical sciences, earth applications, and space
The Skylab Program will produce information that will enhance present scientific knowledge
and perhaps extend the frontiers of knowledge on subjects ranging from the nature of the
universe to the structure of the single human cell. It is the objective of the National
Aeronautics and Space Administration that the knowledge derived from the Skylab
Program's investigations be made available to the educational community for applications to
high school education at the earliest possible date.
For this reason, the Skylab Education Program was created to assure that maximum
educational • benefits are obtained from the Skylab effort, documentation of Skylab
activities is adequately conducted, and understanding of scientific developments is
This document, one of several volurnes prepared as part of the Skylab Education Program,
has the dual purpose of (1) informing high school teachers about the scientific investigations
performed in Skylab, and (2) enabling teachers to evaluate the educational benefits the
Skylab Program can provide. .'
These books will define the objectives of each experiment, describe the scientific
background on which the experiment is based, outline the experimental procedures, and
indicate the types of data anticipated.
In preparing these documents an attempt has been made to illustrate relationships between
the planned Skylab investigations and high school science topics. Concepts for classroom
activities have been included that use specific elements of Skylab science as focal points for
demonstrations of selected subjects. In some areas these address current curriculum topics
by providing practical applications of relatively familiar, but sometimes abstract principles;
in other areas the goal is to provide an introduction to phenomena rarely addressed in high
school science curricula.
It is the hope of the National Aeronautics and Space Administration that these volumes will
assist the high school teacher in recognizing the educational value of the information
resulting from the Skylab Program which is available to all who desire to make use of it.
Readers are asked to evaluate the investigations described herein in terms of the scientific
subjects taught in secondary schools. The related curriculum topics identified should serve
as suggestions for the application of Skylab Program-generated information to classroom
activities. As information becomes available from the Skylab Program, announcements will
be distributed to members of the educational community on the NASA Educational
Programs Division mailing list. To obtain these announcements send name, title, and full
school mailing list (including zip code) to:
National Aeronautics and Space Administration
Washington, D.C. 20546
Mail Code FE
This volume covers a broad spectrum of scientific investigations on Skylab that have been
designed to improve man's understanding of himself and his physiological functions and
needs. Additionally, a small group of related studies on the biochemical and biophysical
behavior of lower organisms and single human cells in the weightless environment of space is
included. . , .
So that the reader will have a better understanding of the timing, setting, and scope of the
total scientific endeavor on Skylab, a brief description of the Skylab Program has been
Valuable guidance was provided in the area of relevance to high school curricula by Dr.
James R. Wailes, Professor of Science Education, School of Education, University of
Colorado; assisted by Mr. Kenneth C. Jacknicke, Research Associate on leave from the
University of Alberta, Edmonton, Alberta, Canada; Mr. Russel Yeany, Jr., Research
Associate, on leave from the Armstrong School District, Pennsylvania; and Dr. Harry Herzer
and Mr. Duane Houston, Education and Research Foundation, Oklahoma State University.
The Skylab Program
The Skylab orbiting space station will serve as a ^yorkshop and living quarters for astronauts
as they perform investigations in the following broad categories: physical sciences,
biomedical sciences, Earth applications, and space applications.
The spacecraft will remain operational for an eight-month period, manned on three
occasions and unmanned during intervening periods of operation. Each manned flight will
have a crew of three different astronauts. The three flights are planned for durations of one
month, two months, and two months, respectively.
A summary of objectives of each of the categories of investigation follows.
Observations free of filtering and obscuring effects of the Earth's atmosphere will be
performed to increase man's knowledge of (1) the sun and of its importance to Earth and
mankind, and (2) the radiation and particulate environment in near-Earth space and the
sources from which these phenomena emanate.
Observations under conditions different from those on Earth will be made to increase man's
knowledge of the biological functions of living organisms, and of the capabilities of man to
live and work for prolonged periods in the orbital environment.
Techniques will be developed for observing from space and interpreting (1) Earth
phenomena in the areas of £^culture, forestry, geology, geography, air and water pollution,
land use and meteorology, and (2) the influence of man on these elements.
Techniques for adapting to and using the unique properties of space flight will be developed.
The Skylab Spacecraft
The Skylab cluster contains five modules (see illustration).
1) The orbital workshop is the prime living and working area for the Skylab crews. It
contains living and sleeping quarters, food preparation and eating areas, and personal
hygiene equipment. It also contains the equipment for the biomedical science experiments
and for some of the physical science and space applications experiments. Solar arrays for
generation of electrical power are mounted outside this module.
2) The airlock module contains the airlock throu^ which suited astronauts emerge to
perform activities outside the cluster. It also contains equipment used to control the
cluster's internal environment and the workshop electrical power and communications
3) The multiple docking adapter provides the docking port for the arriving and departing
command and service modules, and contains the control center for the telescope mount
experiments and systems. It also houses the Earth applications experiments and materials
science and technology experiments.
4) The Apollo telescope mount houses a sophisticated solar observatory having eight
telescopes observing varying wavelengths from visible, through near and far ultraviolet, to
X-ray. It contains the gyroscopes and computers by which the flight attitude of Skylab is
controlled. Solar arrays mounted on this module generate about half of the electrical power
available to the cluster.
5) The command and service module is the vehicle in which the crew travels from Earth
to Skylab and back to Earth, and in which supplies are conveyed to Skylab, and experiment
specimens and film are returned to Earth.
Skylab will fly in a circular orbit about 436 kilometers (235 nautical miles) above the
surface of the Earth, and is planned to pass over any given point within latitudes 50° north
and 50° south of the equator every five days. In its orbital configuration, Skylab will weigh
over 91,000 kilograms (200,000 poimds) and will contain nearly 370 cubic meters (13,000
cubic feet) for work and living space (about the size of a three bedroom house).
1 Apollo telescope mount 6
2 Solar arrays 7
3 Sleeping quarters H
4 Personal hygiene 9
5 Biomedical science experiment
Figure 1 Skylab Orbiting Station
Ward room 10
Orbital workshop 1 1
Experiment compartment 12
Airlock external hatch 13
Multiple docking adapter
Earth resources experiments
Command and service module
Skylab Life Science Investigations
Major study emphasis in the Skylab Program is on life sciences as summarized in Figure 2.
The human body incorporates a large number of interdependent body systems in
homeostatic balance, which is essential to the })roper functioning and well being of the body
as a whole. Therefore, the program shown in figure 2 recognizes that measurement of
change in a single body system or function is not a final answer in itself. Ultimate answers
require a considerable amount of cross correlation among the six principal study areas.
The si.\ areas of scientific investigations being emphasized in Skylab appear on the left side
of the figure. The investigative program for these areas includes measurement of individual
events and subsequent integration of all data to establish the effects of interactions.
The inquiring reader of this book can discover that the educational potential of the program
of investigations discussed is not limited to the specific scientific thrust of the experiment
but has a broader association which cuts across many elements of the high school
curriculum. Thus, the general subject area of this book, life sciences, can provide source
material in such diverse fields as physics, biology, and chemistry.
Table 1 is a cross index of general curriculum elements to specific investigations within the
Skylab Life Sciences Experiment program.
Nfineial and Hormonal
MO 71 Mineral Balance
M078 Bone Mineral
M073 Bioassy of
M092 Lower Body
Ml 71 Metabolic
Studies of Blood
Ml 12 Man's Immunity
in vitro Aspects
Ml 13 Blood Volume
Red Cell Life Span
Ml 14 Red Blood
Ml 15 Special
SOI 5 Effects of Zero-g
on Sin^e Human CeDs
S071 arcadian Rhytiim,
Pocket Mice "
S072 Circadian Rhythm,
Ml 31 Human
Ml 33 Sleep
Figure 2. Experimental Program
Table 1 Related Gurriculum Topics
MINERAL AND HORMONAL-
Calcium exchange in -
of mineral constituents,
of protein, waste proc-
essing osmotic pressures,
calcium replacement by
Sr In bones
Cyclic menus, nutrient
parameters, food prepara-
tion and consumption
in a unique environment,
effect of diet in bone
development; caloric, con-
tent of food ■
X-ray techniques, mass
measurement in zero
Nutrition, metabolism, -
mineral- and hormonial bai-
bones and blood, digestive
tract, role of hormones,
structure and function;of
nephron units, bone de-
Techniques of blood,
urine, vomitus and
Protein analysis, DNA
and RNA analysis, blood
analysis, enzyme struc-
ture.-ATP cycle bonding
in biochemical cycles,
O2 and CO2 transport
meiosis studies,-^ body
defense against disease;
vaccines; function of
blood cells, cell produc-
tion and' destruction;
function of enzymes, ex-' -.
amination of bone marrow
Gas. laws, partial pres-
sures, .equilibrium, ..
location and.function of .
Fluid dynamics of cardio-
vascular system, dynamics,
of zero gravity; mechanical.
failures of the^circulatory
systems; hydrostatics^ .
Role of' gravity in cir-
culatory system, blood
rate, effect of CO2 on
shock integration of
design, positive and**-
Measurement of Oj intake-
vs CO2 output, caloric-
determination of nutrients,
Caloric-content of'foods, »"
Work- output, and gas. flow
Toxic substances and
vital capacity, metabo--
lism of plants,- breath-..
ing rate after exercise, .
CO2/O2 ratio;effects on
design and integration • -
of engineering and
scientific disciplines '
Electrode design, sound in-^
low pressure atmosphere;
fluid dynamics .
Exercise related to touch,
vision, smell', hearing,
sickness; sense functions-
of brain, sleep habits,' .
vestibular functions, .
Studies of motion, -
touch psmell, hearing
integration ofsenses,- .
electrochemical nature •-,
of nerve impulses; ion c-
transfer across a mem- ■ ■
- brane, ionic. potention.'
of an axon
System design, feedback
servo systems, digital .
logic, integration of ^
engineering and scien-
tific disciplines, space
Analysis of body fluids
pressure, manual dex-
terity ; drug effective-
ness, circadian rhythm
of mice; fruit flies,
Drosoph ila- genetics,-
mitosis and cell struc-
ture, chromosome aber-
gene mapping, blood
EXPERIMENTS PROGRAM BACKGROUND
Manned Since the beginning of manned spaceflight in the United
Spaceflight States, there has been a continuing concern regarding man's
ability to live and operate efficiently while on extended
flights in space. Answers to this concern can be obtained only
through a careful quantitative assessment of the crews'
performance and physiological well being while working in
the space environment. The study must develop data on
trends and rates of adjustments while providing an
instantaneous assessment of the crewmen's status and
performance at critical points during the flight. Equally
important is the ability of the crew to readjust to life on
Earth after return from orbit. Interpretation of data depends
on comparing flight results with a data base obtained in
ground laboratories. Such a combination of ground and
inflight experimentation forms the basic plan for the Skylab
Missions up to 14 days have produced changes . in the
astronaut's body tissues and systems as expected. Although
the vector of these changes has been in the expected
direction, individual changes have often differed from the
predicted value. While these earlier missions have shown that
man's gross capabilities to operate in the space environment
continue at or near Earth equivalence, new techniques for
performing a given task on orbit have sometimes been
required to reflect the unique character of the space
The Skylab Program and the life science experiments that are
to be performed offer an opportunity to increase man's
knowledge of the biological and physiological functions of
living organisms. This will be achieved by making scientific
observations of living organisms in an environment different
from that on Earth, and evaluating the transitional effects as
the organism responds and hopefully adapts to these new
Specificcdly, the Skylab biomedical experiments provide Data requirements for long
information on man's ability to- duration spaceflight planning
1) perforrh effectively while in near weightless flight up to
2) identify natural biological cycles,
3) identify the adequacy of or need for additional
life-support provisions to control changes in body
chemistry within acceptable bounds,
4) confirm or refine the habitability design criteria for
future long-duration manned systems.
In addition, information will be developed to aid in
understanding crew psychological reactions to long-duration
confinement; evaluating the problems associated with food,
water, and waste management; and for developing criteria for
designing better crew-nionitoring systems for future missions.
The Sky lab Program should provide these data at a
sufficiently early date to affect the next major manned
In terms of life-science reseairch, Skylab aims primarily at
identifying and defiriing physiologic and psychologic adaptive
changes and establishing whether these will be progressive or
self-limiting. If progressive, they could necessitate returning a
crew back to Earth before the scheduled time. If self-limiting,
the crew should pass through a period of adjustment
followed by stabilization appropriate to the new
environment. It is well knovra that when man travels to a
high-altitude city or works in an undersea environment for
long periods, the body processes pass through an initial
adjustment followed by stabilization at new levels
appropriate to survival in the new environment. This
transient adjustment is also expected for the Skylab crew.
The new stable levels of accommodation are expected to be
adequate for the normal health and function of man during
continued orbital flight. Upon return to the terrestrial
environment the space-stabilized levels of accommodation
may become significant factors in the crews' well being; that
is, the acclimatization to space which has occurred may
require specialized assistance to help the crewmen readapt to
Earth following long duration space flight. Based on shorter
duration past missions, the predicted course of events is
encouraging for these longer manned spaceflights.
The experiments selected for Skylab reflect a synthesis of the
observations made during previous flights. Body systems
which have shown changes and which could present a
problem for the crewmen have received priority in this
These studies have been organized for the purposes of this
document in the following order:
Section 2, Mineral and Hormonal Balance
Section 3, Hematology and Immunology
Section 4, Cardiovascular Status
Section 5, Energy Expenditure
Section 6, Neurophysiology
Section 7, Biology
Acclimatable and accommo-
dative reflexes trigger transi-
tional adjustments in body
In each section a general introductory background is
included. The purpose of this background is to estabhsh a
fundamental relationship between the experimental program
and basic classroom science. This background is oriented
towards establishing a broad scientific link between the
Skylab experimental program and classroom science
curricula. Hence, this approach emphasizes the general
scientific background of the experimental program and
separates the Skylab technological goals from the broader
teaching aspects. Other subsections describe the specific
technical objectives, equipment, and expected data output
from each experiment.
Skylab Experiment ivi071
BioassVrOf Body Fluids
Skylab Experiment IVlb73
Bone Mineral Measurement
Skylab Exjseriment M078
In order to maintain life, an oi^anism must be able to
coordinate a wide variety of different functions. For this
purpose, animals, including man, have developed two
importamt communication systems. The nervous system has
the form of an elaborate telegraph (neural) network in which
communications paths are reasonably well defined by
anatomical connections which, in many cases, provide very
specific routing of transmitted messages to discrete
anatomicEil sites. The other communication system is the
endocrine system consisting of many ductless glands (Figure
2-1). In it, messages are carried in the bloodstream in the
form of complex chemical substances (hormones) that
interact with special cells to receive the hormone and to react
to it in a specific way. These "target cells" may be limited to
one particular type of cell, e.g., the gonadal cells that respond
to the gonadotrophic hormone, or the renal tubular cells that
respond to aldosterone. However, some hormones, such as
insulin, act upon many different types of cells.
Hormones— any of various
internally secreted compounds
formed in endocrine organs that
affect the functions of receptive
organs when carried to them by
^^^^BjHWH^^^^^^^^B Brain ^^^^^^^^^^^^|
^^HSg^EBM||^^^^B^^9 Hypothalamic Nuclei ^H
^^^^^^^^^^^^^^^^^^^ Hypophysis (Pituitary) H
^H^^^^^B Adrenal Cortex ^M
^^^^^^^^ Adrenal Medulla H
^^^ Testes male) ^^^|
^^^[ Ovaries (in female) ^^^J
Figure 2-1 Major Endocrine Glands in Man
Neuroendo- There are many interactions between the nervous and
crine System endocrine systems, so that they are sometimes considered
collectively as the neuroendocrine system. For example,
transmission between neurones in the sympathetic nervous
system occurs via adrenergic hormones. These hormones are
also produced by the adrenal medulla, an organ which
functions as an endocrine gland, but is embryologically
derived from neural tissue. Another example of the close
relationship between the neural and endocrine systems is the
requirement that certain hormones be present for the normal
development and functioning of nerve tissue. It is known, for
instance, that lack of thyroid hormone in infancy results in
mental retardation, and in adults in the slowing of
conduction in the nerves. The complex systems which
' control some physiological variables such as body water
content are known to include both neural and endocrine
elements. The type of action which hormones may elicit
from target cells is shown in Table 2-1. The extent of
interactions between the neurohormonal processes and the
basic behavior of target cells is shown in Figure 2-2.
Adrenergic — activated
transmitted by epinephrine.
Table 2-1 Hormone Elicited Control
Altered blood flow to cells, e.g., nearly all tropic
hormones on target glands.
Altered membrane properties of specific cells.
1 ) ADH: renal loop of Henle and H2 transport.
2) Aldosterone: renal proximal tubule and Na*^
3) Various hormones and amino acid transport, e.g.,
178-estradial increases transport by uterus.
4) Insulin: glucose transport; iC transport; Pi
transport; and transport into muscles but not
Altered rates of protein metabolism.
1) Anabolism— increased protein synthesis e.g.,
a) GH: bone, muscle, liver
b) TSH: thyroid; ACTH; adrenal cortex, etc.
c) Thyroxin: many cells
d) Cortisol: liver
2) Catabolism — increased protein degradation
a) Cortisol: muscle, bone
b) Thyroxin (large doses): many cells
Altered enzymatic activity
1) CHO Metabolism e.g.,
a) Epinephrine: liver, muscle phosphorylase
b) Insulin: muscle and glycogen synthesis
2) Lipid metabolism
a) Many hormones: lipolysis in adipose
b) Insulin: antilipolysis in adipose tissue.
Mineral, water and electrolyte metabolism
Effects may be secondary to those listed in categories
above, e.g., PTH and Ca** mobilization may be
secondary to increased catabolism of bone protein, or
altered membrane changes.
Change in External of
Output = Alteration in Metabolic Behavior of Target Cells
Figure 2-2 Neurohumoral Interactive Processes Influencii^ Metabolic Activity of Specific Cells
Referring to Figure 2-2, it is apparent that the interactions
are many and complex and further that these actions can be
triggered by outside environmental influences that can affect
component concentration in the plasma, the portal
circulation, and even the brain through sensory organ inputs.
During the evolution of man, gravitational forces have
unquestionably played a major role in his physiological
development. The significance of this force in the health and
growth of man is of uncertain limits today.
Composition One rather interesting aspect of this is demonstrated by the
of Bone - influence which such external forces may have on the growth
of bone in the body.
Bonie is a unique tissue comprising a very special body organ
system. Living bone requires the same nutrients, controls,
and environments as other living tissue in the body. In
contrast, however, to other body tissue and because of its
calcified nature, bone provides, a semipermanent biological
record. Hence, like the growing tree, the structure of bone
records the anomalies of its past including irregularities of
diet, disease, and environment.
Bone shows many levels of organization (Fig. 2-3). Typically,
bones are composed of two basic types of material: compact
(lamellar) bone and spongy (cancellous) bone. Compact bone
makes up the wall of the central portion (diaphysis) as well as
the outer shell of the flared ends (metaphysis). The interior
of the metaphysis is composed of spongy bone which in time
is built up of a collection of plates and bars csilled trabeculae
(little beams). There is little difference in the bony material
in these two types of bone although the porosity of each
type is quite different.
The outer surface of the bone is covered by a membrane
-' . known as the periosteum; the inner surface is covered by a
membrane known as the endosteum. The volume that is
contained within the wall of the diaphysis is called the
medullary cavity and it is filled with marrow as are the spaces
between the trabeculae of spongy bone. Yellow marrow is
found in the large cavities of the long bones. It consists for
the most part of fat cells. It may be replaced by red marrow
in anemia. Red marrow is the site for production of the
granular leucocytes and the erythrocytes (red blood cells).
Red marrow is found in the flat and short bones, the articular
ends of the bones, the bones of the vertebrae, the cranial
dipole and the ribs. Both types of marrow have a supporting
connective tissue and numerous blood vessels.
Cancellous— of a reticular,
spongy, or lattice-like structure:
used mainly of bony tissue.
Diaphysis— the shaft of a long
Metaphysis— the wider part at
the extremity of the shaft of a
long bone, adjacent to the
Bone is formed by cells called osteoblasts, and destroyed or
resorbed by other cells called osteoclasts. These two cell
types are formed from undifferentiated mesenchyinal cells
lying on the surface and in the spaces of the bones. When a
• Line of Epiphyseal
■ Articulate with
Fetalis and Tibia
Figure 2-3 Structiure of Human Femur
certain stimulus is received, these mesenchymal cells begin
functional and morphologic transitions which terminate in
the formation of specilized osteoblasts and osteoclasts as
appropriate to the stimulus. The deposition or mobilization
of calcium under the influence of structural loads on the
bone completes the growth of new adult bone. Bone cells
(osteocytes) were originally osteoblasts which became
included in the bone matrix. They are the living elements of
bone tissue and their function is to maintain the chemical
environment of the surrounding nonliving tissue. In lamellar
bone, there Eire about 20,000 osteocytes per cubic millimeter,
residing in the same number of lacunae (spaces) and they are
about 10 X 15 X 25 microns in size. Osteocytes die for a
variety of reasons; after death they are absorbed and leave
empty lacunae behind. Human osteocytes live an average of
There are a wide variety of observations that indicate that the
growth system, whose function is to penetrate and remodel
Osteoblast— a cell that arises
from a fibroblast and which, as
it matures, is associated with the
production of bone.
Fibroblast — a connective tissue
Osteocytes — an osteoblast that
has become imbedded within the
bone matrix, which connects to
other osteocytes to form bone.
bone, is somehow responsive to the local state of stress; that
is, physical loads of various kinds alter the growth rate,
shape, and structure of bone.
Bone Measurements of bone weight show that inactivity through
Measurement confinement, immobilization, or paralysis causes a significant
reduction in both the amount and quality of bone. Several
studies of this phenomena involving patients immobilized in
pelvic girdle and leg casts have been made. During the
confinement period, significant levels of calcium,
phosphorus, and nitrogen were found in urinary and fecal
excretions. Animal experiments indicate that immobilization
of a limb invariably leads to disuse atrophy and a reduction
in muscle and bone weight.
Long bones with an angulation caused by a poorly set but Angulation— the formation of a
healed fracture have been observed in children to gradually sharp obstructive angle
straighten. These changes and adjustments in shape require
bone to be resorbed on the tension or minimum compression
side and deposited on the more heavily loaded side. Thus, it
can be observed that the bone cross section drifts in a
direction to minimize loading eccentricity so that bone
appears to possess a stress directed growth regulating
mechanism which adjusts the bone architecture in response
to external loads.
Generally, it can be said that usage in the young growing
skeleton leads to changes of shape and structure while in
older, fully grown bones usage leads mainly to changes in
structure. It is as if the growing bone would grow into a new
pattern, determined by mechanical forces, while fully grown
bone has become more rigid in its outer shape, but can adapt
to changed forces by a new orientation of its internal
The skeleton diuing man's daily activities is exposed to a
wide range of loads varying in me^itude and direction. The
growth stimulus will therefore also vary in both intensity and
direction. Thus, bone organization in the adult is finally
determined by those activity patterns most frequent in the
lifetime of the individual, superimposed, of course, on the
genetically controlled pattern unique to the species. Activity
patterns not characteristic of the species would therefore be
expected to stimulate growth contrary to genetically carried
traits, and result in a bone weakened for characteristic
activities of the species.
The Skylab Program affords a unique near-weightless
environment in which to test many of the theories that have
been advanced as to the manner in which body health and
growth are influenced by the environment, and specifically to
evaluate the role of mineral balance and neurohumoral
influence on this growth.
SKYLAB EXPERIMENT M071
Mineral Bed rest immobilization studies have shown that in healthy
Balance young adults urinary calcium increases to 2-3 times the
control level within 5 weeks after confinement. X-ray studies
of the bones have demonstrated demineralization as early as
2-3 weeks after immobilization. Gemini pre- and postflight
x-rays have suggested a similar loss of mineral from peripheral
bones; the Gemini 7 mineral balance experiment has
demonstrated a trend toward negative mineral balance.
Continuous losses of calcium and nitrogen, such as those
during long duration missions, mi^t result in impairment of
skeletal and muscle integrity and the formation of kidney
stones. Identification of the rates of actual deterioration will
allow specific countermeasures to be taken on later flints,
such as the institution of exercise routines and the
manipulation of dietary constituents.
The principal method of assessing the effect of a stressor on
the biochemical integrity of the skeletal and muscular
systems is to determine whether the stressor promotes a
catabolic response that is greater than the anabolic
capabilities of the tissues. The change in equilibrium may be
reflected in an imbalance between the nutrient intake of the
constituent in question and the output of it and/or its
metabolites. A state of negative nitrogen or calcium balance
is not itself detrimental unless it is of an extent and duration
that results in compromise of the integrity of muscle or bone
with resultant increases in susceptibility to disease or actual
pathology. Prior to the onset of recognizable disease,
however, minor changes in function suggesting later
deterioration can be demonstrated. ^
Stressor— a stimulus, such as pain
or fear, that disturbs or
interferes with the normal
physiological equilibrium of an
Anabolism — any constructive
process by which sample
substances are converted into
more complex compounds,
Catabolism— any destructive
process by which complex
substances' are converted by
living cells into more simple
The objective of this experiment is to determine the effects
of space flight on the muscle and skeletal body systems by
quantitative assessment of the gains and losses of biochemical
constituents of metabolic importance. These constituents are
water, calcium, phosphorus, magnesium, sodium, potassium,
nitrogen, urea, hydroxy proline, creatinine and chloride.
The Mineral Balance and Bioassay of Body Fluids experiment
data were obtained from a detailed, daily inventory of food
£ind water intake, of body mass, and of output of waste
products. Waste products, feces, urine and vomitus are
measured, processed, and stored onboard for return to E£ui;h
with the crew, and subjected to detailed analysis. Equipment
designed to perform the specimen and body mass
measurement, M074 and M0172, respectively, is used to
support this experiment.
Experiment The performance of the Mineral Balance Investigations starts
Investigations 21 days before flight and continues throughout the flight and
for 18 consecutive days after return to Earth. Each day of
the observing period, the following functions will be
performed by the crew:
1) Body weight (or mass) will be measured immediately
after the first urine voiding following the sleep period.
2) A predetermined diet will be used since the composition
of the crewman's diet must be known and carefully
controlled. In the preflight period, each crewman will use
this diet to allow the 'establishment of individual
metabolic equilibrium. Every effort will be made to make
the diet palatable. The premeasured menu for each meal
will be prepared and the mass of any leftover food will be
measured and recorded.
3) Fluid can be taken as desired, but all intake will be
recorded. This includes fluid used for food
4) All urine, feces, and vomitus wUl be collected pre- and
postflight and preserved for analysis. Inflight, the amount
of daily urine output from each crewman will be
determined, and a measured homogeneous sample of at
least 45 milliliters (2 for tracer method volume
determination) taken, frozen, and stored for analysis. All
feces and vomitus passed will be collected, the mass will
be measured, and the specimens will be dried and stored
for postflight analysis.
5) Periodic blood samples will be taken and the
concentration of selected constituents determined.
Inflight blood samples will be processed and frozen for
During the Skylab Program, three crews (three men in each)
will occupy the orbital workshop on three separate occasions.
The initial mission will last up to 28 days and the other two
for up to 56 days each. The Mineral Balance Experiment will
be performed on all three missions so that by the end of the
Skylab Program a continuous quantitative assessment of the
muscle and skeletal body systems for nine different
individuals will have been obtained. For each individual, a
preflight baseline will be followed by a day-by-day profile of
his physiological reaction to the space environment, and
postflight, his readaptation to Earth's normal conditioris.
Specifically, the following data on a daily basis will be
obtained preflight, inflight and postflight:
1) food consumption— nutritional, mineral, and caloric
2) fluid consumption;
3) feces— mass and concentration of biochemical
4) urine— total voids volume and concentration of the
5) vomitus— mass and concentration of the biochemical
6) body mass.
In addition, blood samples will be taken periodically pre-, in-
and postflight. These samples will be analyzed to determine
alkaline phosphates, total protein, electrophoresis pattern,
sugar, calcium, phosphorus, magnesium, sodium, potassium,
hydiroxyproline, chloride, and creatinine.
SKYLAB EXPERIMENT M073 ^
Bioassyof Although many external influences contribute to the
Body Fluids enviroriment . of the human organism as a whole, the
environment of its basic unit, the living cell, is wholly
internal. Since changes in extracellular fluid produce changes
in the composition of the intracellular fluid, it is essential to
the nonnal furiction of cells that the constancy of this fluid
be maintained. This is achieved by the close interaction of
several organ systems, the kidney holding a predominant role.
The kidney, is thus viewed as an organ which not only
removes metabolic wastes, but actually performs highly
important homepstatic functions by adjusting plasma volume
The necessity of elucidating the homeostatic control
mechanisms that govern plasma volume and composition is
evident "when one realizes the complex and, as yet,
unexplained inteiractions of these metabolic and endocrine
controls; Iri the changing external environment, there is a
narirpw, margin within which man's physiological well-being
can" be accominodated by these functions. Evidence exists to
suggest that these- mechanisms may play a significant role in
man's adaptation to stress, including gravity.
Homeostatic — uniformity or
stability in the normal body
states of an organism.
The objective of the Bioassay of Body Fluids Experiment is
to evaluate the endocrinological adaptation resulting from
exposure to the spaceflight environment for periods up to 56
days and to readaptation to the Earth environment.
SpecificaUy, the following elements in blood and/or urine
will be evaluated: adrenocorticotropic hormone (ACTH),
17-hydroxy-corticosterone. (Cortisol), angiotensin II, renin,
aldosterone, antidiuretic hormone (ADH), epinephrine,
norepinephrine, urine electrolytes (sodium and potassium),
urine amd plasma osmolality, extracellular fluid volume, total
body water, serum thyrocalcitonin parathyroid hormone,
serum thyroxine, hydrocortisone, renin activity, total and
fractional ketosteroids, insulin, human growth hormone, and
thyroid stimulating hormone.
The Mineral Balance and Bioassay of Body Fluids data is
obtained . from a detailed, daily inventory of food and water
intake, of body mass, and of output of waste products. Waste
products, feces, urine, and vomitus are measured, processed,
and stored onboard for return to Earth with the crew, and
subjected to detailed analysis in the postflight period.
Equipment for performing the specimen and body ' mass
measurements, M074 and M0172, respectively, is used to
support this experiment.
Bioassy— determination of the
active power of a substance by
testing its effect in an organism.
Experiment The experiments will be accomplished in three phases: (1)
Investigations preflight, for 21 days, (2) inflight, and (3) postflight until
readaptation has been established, beginning immediately
The following functions will be performed each day of the
1) Body weight (or mass) will be measured immediately
after the first urine voiding following the sleep period.
2) A predetermined diet will be used since the composition
of the crewman's diet must be known and carefully
controlled. In the preflight period each crewman vdll use
this diet to establish individual metabolic equilibrium.
Every effort will be made to make the diet palatable. The
premeasured menu for each meal will be prepared and the
mass of any leftover food will be measured and recorded.
3) Fluid can be taken as desired, but all intake will be
recorded. This includes fluid used for food
4) All urine, feces, and vomitus will be collected pre- and
postflight and preserved for analysis. Inflight, the amount
of daily urine output from each crewman will be
determined, and a nieasured homogeneous sample of at
least 75 milliliters for bioassay of body fluids
experiments taken, frozen, and stored for analysis! All
feces and vomitus passed will be collected; the mass will
be measured; the specimens will be dried and stored for
5) Periodic blood samples will be taken and the
concentration of selected constituents determined.
Inflight blood samples will be processed and frozen for
The Bioassay of Body Fluids Experiment will occur on all
three missions so that by the end of the Skylab Program, a
continuous quantitative assessment of the endocrinological
adaptation for nine different individuals will have been
obtained. For each individual, a preflight baseline will be
obtained, followed by a day-by-day profile of his
physiological reaction to the space environment, and after
flight, his readaptation to Earth ■• normal conditions.
Specifically, the following data on a daily basis will be
obtained preflight, inflight, and postflight: '
1) Data obtained from Mineral Balance, Experiment M071
2) Urine — concentration of the biochemical constituents Biochemical-dealing with living
specified in the Objectives. ' matter.
In addition, blood samples will be taken periodically pre-, in-
and postflight and those parameters specified in the
Objectives will be determined.
SKYLAB EXPERIMENT M078
Bone Mineral Stimulus of bone metabohsm is a function of the forces
Measurement exerted on the bone by the attached muscles and the force
exerted along the longitudinal axis of the skeletal system by
gravity. Both forces are altered during complete bed rest and
absence of gravity. Consequently, bone mineral losses have
been associated with long-term bed rest and were anticipated
as a potential problem for the crews of long-term space
In both Gemini and early ApoUo flights, small but significant
losses have been measured in astronaut bone mass. In
contrast to the Gemini and early Apollo studies, which used a
radiographic densitometry technique, the bone mineral
studies performed on Apollo 14, using the gamma ray
absorption technique, revealed no significant losses in borie
mineral content. More data from both ground based and
inflight studies are necessary to resolve the issue before
committing man to extended space travel.
The objective of the Bone Mineral Measurement experiment
is to determine, by a photon absorptiometric technique, the
occurrence and degree of bone mineral changes in the Skylab
crewmen that might result from exposure to the weightless
The Bone Mineral Measurement experiment consists of
preflight and postflight measurement of the condition of two
bones in each astronaut. The ground based equipment for
this experiment is a photon scanning device in which an
iodine-125 photon source is mounted in opposition to an Photon--a quantum of electro-
x-ray detector.- The astronaut's limb containing the bone to magnetic radiation,
be measured is firmly held in the required position within the
scanning device. Foot molds and restraining equipment are
used for accurate positioning of the subject for the scan.
Experiment The Bone Mineral Measurement performance using the
Investigations photon scanner starts 30 days before flight. The bones to be
measured are the heel bone (os-calcis) in the left foot and one
of the bones (radius) in the right forearm. (See Fig. 2-3.)
X-rays of the heel will be made seven days before the first
photon scanner observation.
Preflight scans of the left os-calcis and right radius will be
accomplished on the flight crew, backup crew, and on a
control group 30, 14 and 3 days before the launch of the
Postflight measurements will be made on the flight crew and
on the control group within 10 hours after splashdown and at
the following intervals: 2 to 3 days, 5 to 10 days, and 30 to
45 days if baseline values have not been reached in the 5- to
The measurement on recovery day should be made at the
earliest time possible (within 10 hours) after crew recovery to
minimize the effect of weight bearing by the os-calcis and
maximize the data accuracy on the extent of the bone
mineral losses under zero gravity conditions.
Additional postflight measurements will be required if the
flight crewmembers have not reestablished their baseline
values by the third measurement.
The data returned by this experiment will be the pre- and
postflight bone density measurements of the os-calcis and
radius of each Skylab crewmember (three from the 28-day
mission and six from the 56-day mission) and nine control
group members. The data will be used to determine the
impact of the spaceflight environment on the degree and
occurrence of the bone mineral changes.
Cytogenetic Studies of the Blood,
Si<ylab Experiment Mill (
Man's Immunity, In Vitro Aspects,
Sky lab Experiment M 112
Blood Volume and Red Cell Life Span,
Skylab Experiment Ml 13
Red Blood Cell Metabolism,
Skylab Experiment Ml 14
Special Hematologic Effect,
Skylab Experiment M115
Hematology Hematology, the study of the form and function of blood, in
large part is concerned with changes in the concentration of
the functional elements of the blood. These changes can
come about as the result of disease processes and
environmental changes, or they may be induced as a
Regardless of how these changes are precipitated, if they
exceed relatively narrow physiological limits they will be
accompanied by dramatic changes in the effectiveness of the
individual even to the extent of causing death. The following
discussion is intended to provide a brief resume of the
functions and functional elements that form the basis for our
present understanding of the role of blood in health and
FUNCTIONS OF BLOOD
Every living organism, simple or complex, requires for its
survival, the ability to exchange materials with its
environment, extracting from the environment those
materials which it can metabolize for its energy requirements
and rejecting to the environment those materials which
would poison it. In the case of single cell and other relatively
simple organisms, the process of transmembrane diffusion
provides an effective mechanism for satisfying this need.
Larger, more complex (multicellular) organisms must provide
sophisticated organ systems to accomplish this function since
the external environment makes intimate contact with the
organism's body only at its surface. For example, the skin
surface of the average adult human amounts to only about
1.7 m^ resulting in a surface to volume ratio of about 0.02
mm' /mm^ . Furthermore, this surface is relatively impervious
to most materials, and serves only as a means for eliminating
excess heat and a small amount of water. Hence, the
exchange of materials between the cells of the body and the
external environment must be carried on by specialized
systems such as the lung, kidney, gastrointestinal (GI) tract,
blood, and interstitial fluid.
These specialized systems are related as shown in the diagram
of Figure 3-1. Reference to this diagram shows that while the
lung, kidney, and GI tract interface with the external
environment, they do not interface directly with the cells of
the body. The materials upon which the body is dependent
pass through two intermediate mechanisms, the circulatory
system, and the interstitial fluid. The interstitial fluid, which
bathes all cells in the body, provides a uniform environment
from which the cells extract their material needs and to
which they reject waste products. The circulatory system
provides a transport mechanism that assures physical and
chemical uniformity (within relatively narrow physiological
Interstitial Fluid— that portion
of the body water outside of the
cells and outside of the plasma
limits) of the interstitial fluid. The circulatory system so
permeates the interstital compartment that in the heart, for
instance, no cell is further than about 0.008 mm from a
Vital In addition to the transport of gases, material, and waste
Transport products, blood' has other equally vital functions. These
Functions functions include carrying the heat generated by the cells'
metabolic activity to the surface for easy transfer to the
surrounding environment, and certain defense mechanisms by
which bacteria and foreign particles are removed from the
lli ll i m ill
^k dissolved solids
•* J I ...mil ^ KV-VWWWM '
_ ..: ' Cent •: ii'Ceiill
yi ' " SI ■ ! ■
1 I 17 '1 1 I'M
O2] ■ Lungs! CO2
Figure 3-1 Transport Functions of Blood
• Interstitial fluid
COMPOSITION OF BLOOD
Because of the significant part which blood plays in
maintaining a suitable environment for other tissue in the
body essentially free of foreign matter and infectious agents,
it is inconceivable that changes in the blood would not effect
these other tissues. In recent times we have therefore come to
understand that, in addition to quantity, the quality of blood
is also significant. In order to understand how blood quality
can vary, it is necessary to know something about the
composition of blood.
The blood, which fills the vascular pathways of the
circulatory system, is a truly vmique substance. Even
primitive man probably suspected the vital role that blood
plays and recognized that survival from the hazards of the
hunt and combat were in direct proportion to any loss of
blood. We have £ilready indicated that blood performs many
vital functions which suggests that blood is more than a
simple fluid. Indeed if blood is examined even casusdly it can
be seen to be composed of two phases, a fluid phase and a
cellular phase. This can be easily demonstrated; for example,
if a fresh sample of blood is rapidly cooled and centrifuged
for, say, five minutes, it can be separated into a collection of
heavy particles in the bottom of the sample tube leaving a
clear fluid on top (supernatant). This clear fluid (about 55%
of the sample volume) can be poured off leaving the
separated sediment in the bottom half of the tube. The
supernatant fluid will be noted after a short while to exhibit
a unique property, that is, it will congeal into a jelly like
mass. This liquid phase of the blood which is capable of
congealing is called plasma. If fresh plasma is continuously
stirred with a glass rod, it will be found after awhile that
congealing will not occur. Instead, it will be noted that a pale
yellow material (fibrin) will collect on the stirring rod. The
remaining fluid in the tube, which will now not congeal, is
Returning to the red sediment that was collected, a careful
microscopic examination will reveal that a variety of formed
elements (cells) have been collected.
Cell Types Many studies of these cells have been performed and it is
known • that the cells in the blood include a least three
families of cell types as shown in the tabulation.
1) Granular Polymorphonuclear Leucocytes
Hence, it seems that whole blood consists of at least four
functional elements: plasma, erythrocytes, leucocytes, and
Blood Plasma The plasma has been demonstrated above to include several
components, since fibrin could be isolated by stirring.
_ Actually, plasma is a complex solution of electrolytes and
proteins. The concentration of these plasma constituents
as found in normal blood is tabulated.
ELECTROLYTE COMPOSITION IN BLOOD PLASMA (m eq/liter)
Fibrin— a whitish insoluble
protein that forms the essential
portion of the blood dot.
Function of For the specific roles of each component of plasma, the
Plasma reader is referred to the abundant literature on hematology.
Some of the generalizations which we can note here ascribe
specific roles for plasma in (1) neutralizing the acid end
products of metabolism, (2) regulation of heat loss from the
body, (3) regulation of the proportions of water in the
vascular and interstitial compartments, (4) prevention of
excessive hemorrhage from wounds, and (5) immunological
defense against invading viruses and foreign protein.
The formed cells identified previously are also specialized
with respect to their function in the overall role of blood.
The erythrocytes, responsible for the transport of gases, are
specialized with respect to form and also chemically by the
presence of the protein hemoglobin. The special shape of
erythrocytes, a sort of flattened sphere with a central
depression (Figure 3-2) results in a cell having a large surface
area to volume ratio, which improves the efficiency with
which gases diffuse across the.cell membrane. Simultaneously
this innovative form achieves a low viscosity for efficient
pumping by the heart. The presence of hemoglobin in
erythrocytes is principally responsible for the gas transport
efficiency of blood. Analysis indicates that at sea level
pressures the oxygen dissolved in blood would be
approximately 3 ml per liter of plasma. Under similar
conditions the presence of hemoglobin increases the oxygen
concentration to approximately 200 ml. The actual manner
by which gases are taken up by the red cells is not nearly as
simple as this discussion may imply and the reader, is referred
to the many good texts for an in-depth treatment of this
Hemoglobin — the
oxygen-carrying pigment of the
Plasma— the fluid portion of the
blood in which the corpuscles
Figure 3-2 Erythrocyte
The leucocytes, as noted previously, comprise a spectrum of
cell types. Observations made with blood suggest that these
cells have been specialized to remove bacteria and foreign
particles from the blood. Other evidence suggests that the
biilk of the activity of leucocytes, however, takes place
outside of the vascular pathways. The leucocytes therefore
are transient residents of the blood stream on their way to
some location in the tissue where they may be needed to
destroy invading bacteria or particulate matter. Leucocytes
perform their function by a process of phagocytosis
(ingestion and digestion).
No one knows with any certainty the origins of each of the
cell types nor is the exact role of each in the body's defense
known. Some generalizations that can be made, however, are
that the three varieties of granulocytes are transported by the
blood to tissue sites where they disintegrate releasing active
enzymes, (1) the neutrophils that are specifically active in
phagocytosis of bacteria, (2) the lymphocytes that circulate
continuously between the tissue and bloodstream and are
active in immune responses, and (3) the monocytes that are
circulating phagocytes active in phagocytizing nonliving
The platelets are very small and can be easily overlooked in
the blood. They are known to be cell fragments originating in
bone marrow and tend to disintegrate readily. Platelets carry
substantial amounts of serotonin, a vasoconstrictor which is
active in reducing blood loss from severed vessels.
Additionally, platelets are believed to play a significant role
in the maintenance of the endothelial lining of the vascular
Phagocyte —any cell that ingests
microorganisms or other cells
and foreign particles.
INFLUENCES ON BLOOD
Environmental Most of US would have little difficulty accepting the premise
Conditions that disease can influence the form and function of blood.
Most are even vaguely aware that the external environment,
particularly radiation in the form of x-rays, can cause
dysfunction of blood. Many, however, will not recognize that
environmental changes considered to be physically tolerable
may stress the circulatory system, including the
hematopoietic (related to blood forming) process and the
immunological mechanism, beyond acceptable physiological
A commonly recognized physiological response to changed
environmental conditions is found in the deeper and more
rapid breathing which is experienced when we go to
unaccustomed high altitudes. This accommodative reflex is
the body's response to the hypoxic (low oxygen) atmosphere
of the new environment. If this stress persists for a long
enough period of time, compensating changes will be made in
the functional elements of the blood; that is, the body will
generate more erythrocytes (red blood cells) so as to increase
the oxygen-carrying capacity of the blood. This latter change
is an acclimatizing change which minimizes the energy
expended in maintaining an adequate level of oxygen in the
blood. This acclimating process, however, is not without
penalty since the resulting "higher hematocrit" (increased red
cell content of the blood) increases the viscosity of the blood
and imposes added pumping loads on the heart. If large
environmental changes of this type were permanently
endured, serious consequences might result. It is to be
expected, that even more subtle changes in the blood may be
provoked by other environmental changes. Since some of
these changes could produce irreversible damj^e to the body,
it is essential to understand how these changes may occur and
what physiological limits may be endured without harm.
Hematocrit— the volume
percentage of erythrocytes in
Orbital ' flight in a spacecraft such as Skylab provides a
laboratory having an artificially maintained atmosphere, near
weightlessness, and nearly closed ecological environment.
Studies conducted here may provide new information
relating to man's ability to acclimate safely to spaceflight and
may also provide valuable insight into the underlying
mechanisms by which these changes are accommodated.
The Skylab Hematology and Immunology experiments
described on the following pages include five investigations to
evaluate specific aspects of man's immunologic and
hematologic systems that might be altered by or respond to
the spaceflight environment. The biochemical functions
investigated with these experiments include (1) cytogenetic
damage to blood cells, (2) immune resistance to. disease, (3)
regulation of plasma and red cell volumes, (4) metabolic
processes of the red blood cell, and (5) physical-chemical
aspects of red blood cell functions.
The investigations being conducted are not meant to provide
an all inclusive coverage of immunohematologic functions,
but are expected to serve as sensitive indicators of
stress-induced changes in these functions in man. Selection of
these specific protocols has been based upon experience
gained from previous manned spaceflight missions and
associated ground based studies. The specific goals of these
experiments are to determine—
1) environmental factors responsible for the loss of red cell
mass noted during the Gemini Program;
2) relative roles of the 100% oxygen environment, nitrogen
in small amounts, weightlessness, duration of exposure,
diminished red cell production versus increased
destruction, ambient total pressure, vibration, ambient
temperature, and dietary factors;
3) spaceflight factors responsible for changes in plasma
4) influence of long-duration spaceflight on the coagulation
process, platelet function, and vascular friability, and to
assess the environmental factors responsible for such
5) any alterations in inflammatory response that may occur
as a result of long-duration spaceflight, and evaluate;
6) extent to which spaceflight may influence mitosis (cell
division) and/or chromosomal composition, and which
environmental factors are responsible and what
preventive action can be taken if such changes do occur.
SKYLAB EXPERIMENT Mill
Because chromosome aberration yields in peripheral blood
leucocytes have been found to be sensitive indicators of
exposure to radiation, such measurements can be employed
as in vivo dosimeters.
In mitosis (cell reproduction), each chromosome duplicates
itself with the duplicates being separated from each other at
cell division. One duplicate chromosome goes into the
nucleus of one daughter cell and the other duplicate goes into
the nucleus of the second daughter cell. The end product of
this process is cell division which involves several phases.
Each phase is characterized by a particular pattern of
chromosome behavior. It is during one of these phases (the
metaphase) that chromosomal aberrations may be
Chromosome analyses were done for all of the Gemini
missions (with the exception of Gemini VIII which was
terminated early) under the operational medical program.
Significant, though slight, increases in some types of
chromosomal aberrations were seen following some of the
missions. This effect could not be correlated with mission
duration, extravehicular activities, isotope injection of the
crews or other obvious flight parameters. Observations on the
Skylab crewmembers can assist in elucidating the mechanism
of this phenomenon.
Measurement of the number of chromosome aberrations has
been demonstrated by ground based studies to be a sensitive
method of biological radiation dose estimation. Ambient
radiation encountered during long duration missions or
unexpected solar flare events could produce significant
increases in aberration levels. Even if no detectable increases
in aberration levels are observed in the Skylab missions, the
experiment will have served the useful purpose of
demonstrating the lack of a detectable genetic hazard
associated with these missions.
Metaphase — the middle stage of
mitosis during which the
lengthwise separation of the
chromosomes in the equatorial
The method of detecting chromosomal aberration will be
visual analysis that involves counting the chromosomes, the
number of breaks, and types where possible, and then making
a comparison between the identifiable chromosome forms
with groups of chrornosomes that compose the normal
human complement. '
Standard statistical procedures will be used to determine if a
significant increase ' in aberrations appears postflight. This
analysis will include comparisons of preflight aberration
levels in normal individuals of the general population.
"Predicted" aberration levels for postflight samples will be
calculated by using inflight physical dose radiation
measurements (available from Experiment D008, Radiation
in Spacecraft, and other sources) and existing experimentally
determined chromosomal aberration production coefficients.
The effects of any other operational or experimental
procedure likely to produce chromosomal aberration (such as
radioisotope injections) will be measured on normal control
subjects. These control subjects will be similar in age and
physical attributes to the crewmembers. The control subjects
will participate in all tests and medical procedures that are
undertaken by the flight crewmembers. Examination will be
made of the chromosomes of the control members and the
flight crew before initiation of preflight procedures and tests
to detect any chromosomal aberrations already present.
By allowing for predicted aberration yields and the yields due
to experimental or operational procedures, any aberration
frequency difference evident from comparisons of preflight
and postflight samples can be ascribable to radiation or other
The objectives of this experiment are to make preflight and
postflight determinations of chromosome aberration
frequencies in the peripheral leucocytes of the Skylab flight
crewmembers and to provide in vivo dosimetry. These data
will add to the findings of other Skylab cytologic and
metabolic experiments to determine the genetic
consequences of long-duration space travel on man.
Dosimetry— the accurate and
systematic determination of
No inflight hardware is required since the experiment uses
blood samples taken pre- and postflight beginning one month
befpre launch and ending three weeks after recovery.
The leucocytes will be placed in a short-term tissue culture.
During the first cycle of mitotic activity in the in vitro
cultures, standard chromosome preparations of the
leucocytes will be prepared.
The leucocytes from the cell culture will be removed during
metaphase and "fixed." A visual analysis will be performed
which involves counting the chromosomes, the number bf
breaks and types where possible, and then making a
comparison between the identifiable chromosome forms with
groups of chromosomes comprising the normal human
The data from this experiment will consist of the
chromosome aberration frequencies that appear after flight
for nine men, three of whom will have experienced 28 days
in Earth orbit and the rest 56 days each. An estimate of the
radiation dose experienced by each nian will be made based
on the number of chromosome breaks.
SKYLAB EXPERIMENT Ml 12
Information on man's humoral arid cellular immimity and
coagulation phenomena during and following exposure to
space flight is essential before flight crews can be committed
to extended missions. Significant alterations of the iminunity
mechanisms will produce • prejudicial effects upon this
inherent defense system, thei-eby seriously compromising the
crewman's operational status. The cellular immunity system
is exquisitely sensitive to radiation, and the coagulation
status is affected by man's activity.
The experimental program measures itiems which contribute
to man's ability to combat infections and repair traumatized
(injured) tissues after exposure to weightlessness, spacecraft
atmosphere, sublethal ionizing radiation, the monotonous
immunologic stimulation of a closed environment, and the
unusual orientation and physical activity. Significant
alterations of the extracellular or cellular
immune-mechanisms may produce detrimental effects upon
normal physiological functions, may result in increased
susceptibility to infections, and conceivably can induce the
onset of autoimmune diseases.
Autoimmunization — the
production in an organism of
reactivity to its own tissues
The objective of this experiment is to assay changes in
humoral and cellular immunity as reflected by the
concentrations of plasma and blood cell proteins, blastoid
transformations, and the synthesis of ribonucleic acid (RNA),
and deoxyribonucleic acids (DNA) by the lymphocytes
(white cells in lymph).
The inflight blood collection system will draw venous blood
and centrifuge the samples for preservation. Onboard freezing
will be used to preserve the samples during the mission and
maintain them in a frozen state. They will be returned in the
frozen state in a urine-return container for postflight analysis.
This inflight blood collection system and allied facilities will
"" be used to obtain, process, preserve, and return hematology
samples for Experiments M071, M073, M112, M113, M114,
and MH5. (See M115 for more details on this equipment.)
Experiment The experiment will obtain preflight baselines, which will be
Investigations indications of normal metabolism, from the crewmembers
and a control group composed of three men physically
similar to the crewmembers who will serve as controls while
the crewmembers are in spaceflight. Inflight blood samples
will be taken four times from each crewman during the
28-day mission and eight times from each crewman during
the 56-day missions. Upon recovery after the spaceflight,
information will be again obtained from the crewmembers
before body functions "normalize," and compared with the
preflight baselines, inflight profiles, and with the data being
obtained from the ground control group (GCG) to detect any
significant deviations. An extensive battery of analyses will
be performed using appropriate laboratory techniques to
detect qualitative and/or quantitative changes. Periodic
examinations will be made of the blood proteins and
lymphocytes until the possible altered concentrations are
likely to have stabilized. Protocols for the experiment are
given in the section on Experiment Ml 15.
Data will be gathered from blood samples taken preflight,
inflight and postflight. These samples will be analyzed for the
1) total plasma proteins;
2) plasma protein fractions (albumins, alpha globulins, beta
globulins, gamma globulins);
3) lymphocyte morphology;
4) ribonucleic acid (RNA) and deoxyribonucleic acid (DNA)
synthesis rates in lymphocytes;
5) kinetics of lymphocyte RNA and DNA;
6) observation of blastoid formation;
7) lymphocyte functional response to antigen; Antigen— a substance that
8) quantification of 4.5s, 7s, and 19s.
Blood SKYLAB EXPERIMENT M113
Red Cell Life EXPERIMENT BACKGROUND
Environmental factors encountered during spaceflight may
affect the red cell mass and plasma volume. These include
near weightlessness, the spacecraft breathing atmosphere, and
ionizing radiation environments.
Weightlessness may cause a redistribution of the total blood
volume between the arterial and venous segments and by
reducing the quantity of blood in the limbs. In the weightless
state, a redistribution of pulmonary blood volume may occur
with relatively greater perfusion in the apex of the lungs. In
this condition, ventilation and perfusion ratios might be
expected to be similar to those produced when the subject is
lying down in zero gravity. Results from previous missions
suggest that these changes have not produced pathological
changes in the blood vessels. It is not known, however,
whether long-duration missions could predispose to changes
including thrombosis (blood clot). Previous missions have
also led to changes in circulating plasma volume at recovery.
Analysis has suggested that these changes are of a magnitude
similar to those found in bed rest. The rate at which this
change occurs j^nd whether the plasma volume decreases or is
augmented during the stress of reentry is unknown. It is
believed that plasma volume changes may have conti-ibuted
to the temporary orthostatic hypotension and to the decrease
in exercise tolerance that crewmembers experienced soon
The site of red blood cell (RBC) production in the mature
adult is the marrow of membranous bones (e.g., sternum and
vertebrae). The rate of production is dependent on metabolic
demands and the current red cell population. The rate of
RBC production can be measured quantitatively by injection
of a known quantity of a radioactive iron tracer. The
radioiron, combined with globulin, is transported to other
parts of the body. That part of the iron which reaches the
membranous bones is incorporated into the heme portion of Heme — the nonprotein,
hemoglobin by the bone marrow. Since not all the iron insoluble, iron protoporphyrin
appearing in the plasma is used for erythrocyte production constituent of hemoglobin
but is instead taken up by the iron pools of the body, a
fraction of the injected radioiron will be unavailable for
incorporation into developing RBCs. This can be determined
by measuring the concentration of radioiron in the
circulating RBC after seven days and comparing it with the
initial concentration of radioiron in the plasma.
Since the rate of RBC production acts with RBC loss to
increase or decrease the total RBC mass present at a given
time, any changes in the rates of RBC production and
destruction will be necessarily reflected in the red cell mass.
Such changes in red cell mass can be measured. aind analyzed
by injection of radioactive chromium (in the form of sodium
chromate) tagged red cells. The sodiuin chrorhate diffuses
through the cell membrane where it is converted to
chromium chloride and, in this form, bound to hemoglobin.
The volume of RBCs is then calculated by allowing the
chromium-tagged cells to disperse through the circulatory
System and measuring the extent to which the chromium has
become diluted. The fact that chromium doesnot reenter the
red cell makes it a good tracer for RBC mass determinations.
Chromium incorporated into the hemoglobin structure of the
circulating red cell also provides a means for estimating the
rate of random cell destruction by monitoring the rate at
which chromium disappears from the red cell mass.'
Red Cell Life To determine selective age dependent erythrocyte
Span destruction and mean red cell life span, carbon 14 labeled
glycine will be injected into a superficial arm vein of each
crewmember and control subject. The radioactively labeled
glycine, by its incorporation into the heme portion of
hemoglobin, labels the erythrocytes produced on that day.
Sequential blood sampling will then give the percentage of
labeled erythrocytes in the blood at any given time (days),
and by plotting this data, survival and destruction curves can
be obtained. The resultant curves can then be , analyzed
mathematically and a mean life span for the cells determined.
Since only a small portion of the carbon 14 is reutilized in
erythropoiesis, it is an ideal RBC label.
Finally, plasma volume changes can be measured by adding a
known amount of radioiodinated human serum albumin to
each crewmember's blood. Albumin is a major constituent of
the plasma and is the protein most responsible for
maintaining the osmotic pressure at the capillary membrane.
It acts to prevent plasma fluid from leaking out of the
capillaries into interstitial space. ^
E ry thropoiesis— the
The Skylab life support system provides a combination of
breathing gases which because of the lower than normal
nitrogen partial pressure will be hypobaric. The partial
pressure of oxygen in the breathing atmosphere will be
slightly increased at least during extravehicular activity by
the crew. Additionally, the atmosphere will contain trace
amounts of other gases released from onboard equipment and
supplies; Small amounts of other gases may also be released
as a result of the crew's metabolic activity and from bacteria
and molds which may be present.
Hypobaric— characterized by less
than normal pressure or weight
In the Gemini flight, red cell mass decreases were found that
were generally greater than the red cell mass decreases found
in Apollo flight crewmembers. Total pressure of the
atmospheres in the Gemini and Apollo missions were quite
similar while partial pressures of oxygen and nitrogen were
different— more oxygen and no nitrogen . present in the
Gemini missions. It is probable that there were also
differences in the trace gases respired during the missions.
The red cell mass differences in these previous missions were
probably related to the above factors although other factors
might have been important also. As an example, red. cell mass
changes are expected as a result of changes in the amount of
physical activity performed during the . mission. Athletic
conditioning is associated with an increase in red cell mass.
Conversely, red cell mass declines have been found in certain
bed rest studies, although in the studies to date the arnount
of blood drawn for research testing may have been a factor in
the decreased red cell mass.
Since a number of inflight environmental conditions have
been found capable of affecting the total blood volume and
its constituents, delineation of inflight effects on
hematopoiesis is necessary in order to predict the course and Hematopoiesis— the formation of
consequences of long duration spaceflights on future flight blood cells
The objective of this experiment is to determine the effect of
Earth orbital missions on plasma volume and red blood cell
populations with particular attention paid to changes in red
cell mass, red cell destruction rate, red cell life span, and red
cell production rate.
Blood samples will be collected preflight, postflight, and
inflight, and processed in accordance with the protocol
shown in Ml 15.
The data to be collected in support of this experiment
include the following variables:
1) red cell life span;
2) red cell production, distribution, and destruction rates;
3) plasma volume.
Red SKYLAB EXPERIMENT M114
Metabolism EXPERIMENT BACKGROUND
At one time, the red blood cell was believed to be an inert
particle composed of water and hemoglobin. We now know,
of course, that the erythrocj^es are hving cells, doing work,
and requiring energy just as other tissues in the body do. The
average life span of the human red blood cell is estimated to
be 120 days. During this period, it is estimated that the
average erythrocyte travels 100 miles between the heart and
the tissue that it serves. In order to remain functional, the red
corpuscle must (1) maintain an internal environment against
a steep ionic gradient across the cell membrane, (2) resist
forces that try to change its characteristic bi-concave shape to
spherical, (3) maintain active transport mechanisms that
support the metabolic requirements of the cell. Interruption
to these processes would render the red blood cell ineffectual
and would be fatal in a matter of days.
This experiment will assess the influence of the spaceflight
environment on the metabolic processes of red cells. The red
blood cell requires for its energy source a continuous supply
of glucose. The process by which the glucose penetrates the
red blood cell's membrane is not known; however, it is
believed to involve an active transport process rather than
simple diffusion. It is suspected that the membrane's
framework, in particular the fatty (lipid) fraction of the
framework, is functional in this process. Because the
membrane is the dynamic component in the active transport
process, its chemical composition and structural integrity will
be examined by this experiment.
Through the metabolic breakdown of glucose, particularly
ADP (adenosine diphosphate) to ATP (adenosine
triphosphate) energy is stored in chemical bonds. Changes in
the glucose metabolic pathway, which may occur as a result
of spaceflight, will be analyzed by examination of several key
intracellular enzymes found in preflight and postflight blood
The objective of this experiment is to determine if any
metabolic and/or membrane changes occur in the human red
blood cell as a result of exposure to the spaceflight
Enzyme— organic substance
capable of presenting chemical
changes in organic substances by
catalytic action, such as in
EQUIPMENT (See M115.)
PERFORMANCE (See M115.)
The data that will be taken in support of this experiment will
be the preflight, inflight, and postflight values of the
2) reduced gluthathione;
3) glyceraldehyde-6-phosphate dehydrogenase;
4) pyruvate kinase;
5) glyceraldehyde-3-phosphate dehydrogenase;
8) phosphoglyceric acid kinase;
10) lipid peroxide levels;
SKYLAB EXPERIMENT M115
Data collected from pre-Skylab spaceflights indicate that the
spaceflight environment may induce a loss of red blood cells
in the crew. These earlier investigations have suggested that
this loss may result from a self-limiting hemolysis which
appears to be related to alterations in mean corpuscular
volume and increased osmotic fragility. Since reticulocyte
(an early form of the red blood cell) counts which indicate
bone marrow activity have not revealed depression of the
bone marrow activity due to such flights, and since
reticulocytosis (above normal reticulocyte count) did not
appear until the fourth day, it is likely that red cell loss
resulted from a reduced need for red cells for the transport of
Similar data gathered during Apollo missions provided a basis
for comparison vdth the data derived from the Gemini
program. Comparison of these data suggested that a causative
factor in the reduced RBC was the Gemini atmospheric
composition— specifically, the high oxygen concentration.
Data obtained from the later Apollo flights have also
indicated alteration of fluid and electrolyte balance, while
examination of red cell electrolytes by electron probe
analysis indicates similar shifts.
A "bestfit" hypothesis based on these previous data would
have it that the hyperoxic atmosphere in spacecraft (and
possibly other environmental parameters such as
-the liberation of
weightlessness) induces chemical changes in the red blood cell
membrane. These changes directly or indirectly disrupt the
active transpoii mechanisms leading to increased osmotic
pressures and eventual lysis (destruction) of the cell either
through membrane swelling and rupture or through lipid
breakdown and fragmentation.
The objectives of this experiment are to examine critical
physiochemical hematological parameters relative to the
maintenance of homeostasis, and to evaluate the effects of
spaceflight on these parameters.
Inflight^Blood The inflight blood collection system that supports this
Collection related series of studies is designed to collect and process
blood samples without coagulation or contamination. The
inflight blood collection system contains the following major
1) syringes capable of extracting approximately 11
milliliters of venous blood from each crewman under Venous— relating to a vein,
2) small blood sampling vials, into which the crewman
places a few drops of whole blood already containing a
3) automatic sample processors, two-chamber spring-loaded
containers, used to process and separate the blood cells
from the plasma by centrifugation;
4) a two-speed centrifuge used to receive the automatic
sample processors and separate the blood into red cells
and plasma, and to maintain this separation in the
The blood samples for the group of Hematology and
Immunology Experiments will be collected in accordance
with Figure 3-3. Specific handling and processing procedures
will be followed to obtain the data for each of the
Records will be maintained that include sampling times and
the time, name, and quantity of any injections taken
(including x-rays), plus any illness of a subject. A record will
be maintained during the flight of the following events: flight
duration, extravehicular activity, solar events, any abnormal
exposure to radiation, infectious diseases, symptoms of
Inflight blood samples
11 ml blood
Freeze and store ■
Transport to NASA MSC
(cells + plasma)
Angiotensin 1 .
Experiment Ml 13
Red cell life span
Red cell mass •
Experiment Ml 14
Lipid peroxide levels
2, 3 diphosphoglycerate
Experiment Ml 15
Cellular potassium •
Experiment Ml 15
Figure 3-3 Inflight Blood Processing Flow Chart for Hematology and Immunology Series Experiment
illness, use of medication and types of drugs used, with
dosage and duration of usage. Also any deviation from the
expected orbital workshop atmospheric total pressure or
partial pressure of its constituents will be recorded.
Blood samples will be taken inflight four times from each
crewman during the 28-day mission and eight times from
each crewman during the 56-day mission.
Supporting Data in support of Experiment Mil 5 will be taken preflight
Data and postflight only and will consist of information about the
following variables of routine hematology:
1) red cell count;
4) red cell indexes;
5) reticulocyte count;
6) white cell count;
7) differential and morphology;
8) platelet count;
9) acid and osindtic fragilities,
and special hematology:
1) red cell critical volume and red cell volume distribution;
2) hemoglobin characterization;
3) single cell hemoglobin distribution;
4) membrane and cellular ultrastructure;
5) intraerythrocytic electrolytes;
6) red cell electrophoretic mobility;
7) red cell density separation;
8) cellular RNA, protein distribution.
Lower Body Negative Pressure,
Skylab Experiment M092
Skylab Experiment IV1093
The cardiovascular system, one of the vital systems of the
body, functions as a transport media linking man's internal
environment (the interstitial fluid surrounding all cells) with
the three large surface areas exposed to his external
environment (lungs, gastrointestinal tract and kidneys). In
essence, it consists of a very large number of very small
tubular vessels (capillaries) which permeate all regions of the
interstitial fluid and the externally exposed areas of the
lungs, etc. The extensive capillaries are joined by larger
vessels (arteries and veins) to a pump (the heart), thus
forming a closed system through which the transporting fluid
(the blood) is kept flowing at an adequate rate.
Blood Plow The circular nature of the blood flow is demonstrated in the
schematic diagram of the cardiovascular system of Figure 4-1.
The system consists of two capillary networks connected in
series with two piimps to form a closed loop. The two
pumps, the right and left ventricles of the heart, shown
physically separated in the diagram, actually comprise a
single organ. The blood leaving the right ventricle flows to
the capillary bed of the lungs while that leaving the left
ventricle flows to capillaries distributed throughout the rest
I of the body. Each ventricle is preceded by a supporting
atrium, a chamber of the heart, which acts as a receiving
reservoir and auxiliary pump to fill the associated ventricle.
Blood leaves the right ventricle through a single, large vessel,
the pulmonary artery, and enters the left atrium from the
(15 mm Hg)
Arteries — oxygenated blood
Veins— unoxygenated blood
carrying carbon dioxide
Figure 4-1 Schematic Diagram of the Circulatory System
lungs by way of four pulmonary veins; it leaves the left
ventricle through the large aorta, and returns from all parts of
the body by way of two large veins, the superior and inferior
venae cavae. All vessels carrying blood from the heart to
capillaries are arteries, and those conveying blood from
capillaries back to the heart are veins. The circulating blood
volume in man is about 76 ml/kg of body weight, about 5.3
liters in an average man weighing 70 kilograms.
The part of the vascular system traversed by the blood in
going from the left ventricle to the right atrium is called the
systemic circuit. It includes the capillary beds of all parts of
the body except the lungs. The pumping force that moves
blood -through this circuit comes from contractions of the
left ventricle. The large nurhber of capillary networks that
supply the organs and tissue of the body constitute many
circuits connected in parallel and supplied by the extensively
branched arterial system that begins with the aorta. Blood
leaving the capillaries enters small veins that join together to
form larger and larger veins. This arrangement continues until
all the systemic blood returns to the right atrium through the
two large venae cavae. The systemic circuit contains about
80% of the total circulating blood volume, approximately
4240 milliliters for the 70-kilogram average man.
The capillaries, which have very thin and permeable walls,
exchange water and dissolved materials (including gases) with
the interstitial fluid. This two-way passage (in and out) of
fluid has been estimated to exceed 200 liters, per minute.
The capillaries are very small but their number is so large that
the total area available for diffusion is very.largfe, approaching
100 square meters. The number of capillaries in tissue can be
correlated with the metabolism of the tissue; for example, in
a heart muscle where oxygen use is high, microscopic studies
show as many as 6000 capillaries in each square millimeter of
tissue cross section. Since many capiilaries may "close
down," especially in the skeletal muscle except during
exercise or work, the volume of blood present in the systemic
capillaries is variable. It has been estimated that in an average
adult this volume may range between 60 and 200 milliliters.
The systemic arteries act as conduits to distribute blood to
the systemic capillary beds. The aorta at its beginning (the
ascending aorta) has an outer diameter of about 2.5
centimeters and a wall thickness of nearly 2 millimeters. At
each branch point, the cross sectional area of each branch is
smaller than the parent vessel while the total cross sectional
area of the branches is greater. The arteries do not contribute
significantly by diffusion to the exchange of materials with
the interstial fluid. The volume of blood contained within all
the systemic arteries under normal circumstances is estimated
to be about 20% (~one liter) of the total blood volume.
Total Blood Volume- ~5 liters
Volume in Systemic
Arteries- ~i liter
The smallest branches of the arterial system are called
arterioles. Arterioles are different from small arteries in that
their walls are thick in relation to their internal diameter.
This extra wall thickness consists of circumferentially
oriented smooth muscle fibers. The cross sectional area of the
arteriolar lumen varies with contractions of the smooth
muscle which are controlled by neurohumoral factors. These
changes control resistance to blood flow in the systemic
circuit and distribution of the blood flow to the capillary
The veins form an extensive recovery system for conveying
the blood returning from capillary beds to the right atrium.
Although their walls are much thinner than those of the
arteries, they also permit no significant diffusion of
substances through them. The distinctive feature of the
venous system is its large volume. The volume of blood
contained within the veins is about 75% of the volume in the
whole systemic circuit or about 3200 milliliters. Veins, unlike
other vessels, are equipped with one-way valves that permit
blood flow only toward the heart.
Pulmonary The pulmonary circuit, which is sometimes called "the lesser
Circuit circulation," extends from the pulmonary artery as it leaves
the right ventricle to the pulmonary veins as they enter the
left atrium. The pulmonary circuit carries venous blood (i.e.,
blood which has come from systemic capillaries and is
therefore low in oxygen content and high in carbon dioxide
content) to the lungs, where it is converted to arterial blood
(blood which is freshly oxygenated and has had much of the
carbon dioxide removed). The pulmonary artery is the only
artery that carries venous blood, and the pulmonary veins are
the only veins that carry arterial blood. The pulmonary
circuit, like the systemic, is composed of arteries, capillaries,
and veins, but all vessels are generally shorter and larger in
diameter than corresponding systemic vessels. In the
pulmonary circuit thick-walled arterioles are absent and the
very small arteries (<100 microns in diameter) show little or
no smooth muscle in their walls.
In the human lungs, air is conducted via the trachea, bronchi,
and their branches to about 300 million small air sacs or
alveoli, which are honeycomb-like structures about 200 to
250 microns in diameter. The pulmonary capillaries, which Micron— a millionth part of a
are 10 to 14 microns in length, and 7 to 9 microns in meter
diameter, extend as a dense network within the thin,
membranous partitions separating adjacent alveoli.
Calculations have shown the surface aiea of capilleiry wall
exposed to the alveolar air averages to be from 50 to 70
square meters in the average adult. The total volume of blood
within the capillaries of the pulmonary circuit is of the order
of 100 milliliters.
DYNAMICS OF THE CARDIOVASCULAR SYSTEM
Much of our knowledge of the dynamic characteristics of the
cardiovascular system, and the mechanisms governing its
response to changes in activity, environment, and disease has
come from observations on animals, chiefly dogs. In recent
years, great technological advances in bioinstrumentation
have made it possible to confirm and extend these
observations on man. It is still true, however, that many
measurements can be made only on anesthetized animals,
some can be made as well on unanesthetized animals but not
on man, and some on both animals and man in the conscious
state. Under all conditions, the method of measurement used
will disturb, to some extent, the cardiovascular system of the
subject, and influence the variable being measured. It is
always important to minimize this disturbance, to assess its
significance, and to take it into account, when possible, in
interpreting the results.
He mo dynamically, the circulatory parameters of most
interest are pressures and flows in various parts of the
cardiovascular system. Because of the rhythmical
contractions of the heart, the input of blood into both
pulmonary and systemic circuits is intermittent.
Consequently, the blood flow in all the systemic arteries, the
systemic veins close to the heart, and probably all of the
pulmonary vessels is pulsatile rather than steady. In the
systemic capillaries and peripheral veins, the flow is
essentially steady because of the low-pass filtering action of
arterial compliance and arteriolar resistance. Pressures,
therefore, are pulsatile in all four chambers of the heart and
in all parts of the vascular system with the exception of
systemic capillaries and peripheral veins.
Mechanically, the heart is a muscular organ consisting of two
major pumping chambers, the right and left ventricles, each
of which receives blood from a contractile antechamber, right
and left atria, respectively. Backflow of blood from ventricle
to atrium is prevented by the valve on the right side
(tricuspid) and the valve on the left side (mitral). The right
ventricle ejects blood into the pulmonary artery from which
backflow is prevented by a semilunar pulmonary valve.
Backflow of blood into the left ventricle from its outflow
vessel, the aorta, is prevented by a similar semilunar aortic
Diagram of Human Heart
An outstanding characteristic of cardiac activity is the fact
that the heart continues to contract rhythmically when all of
its connections with the nervous system are severed, or even
when it is removed completely from the body. This indicates
that, unlike skeletal muscle, cardiac muscle is not dependent
upon impulses coming to it from the nervous system for its
activation. It has the property of automaticity.
Au tomatici ty— occurring
Normally, the rhythmically occurring stimuli responsible for
cardiac contraction arise in the sinus node. This "built-in
stimulator" or pacemaker of the heart has the property of
automatically discharging rhythmical stimuli which activate
the heart. This wave of excitation, beginning in the sinus
node and traveling in all directions through the atrial muscle,
is known as the cardiac impulse. It consists of electrical
(action currents), chemical and thermal changes, and is
followed closely by mechanical contraction. As in the case of
a nerve impulse traveling along a nerve fiber, or in impulse
traversing a single skeletal muscle fiber, the cardiac impulse
also involves a progressive depolarization of cell membranes.
Depolarization — the
Contraction The normal sequence of contraction of the heart chambers
Sequence results from the spread of the cardiac impulse. This impulse
arises in the sinus node, located in the wall of the right
atrium; hence this chamber contracts first. Because the rate
of conduction of the impulse through atrial muscle is quite
rapid, the left atrium contracts only a very short time after
the right. Practically, the two atria contract almost
simultaneously. The impulse is slowed down considerably,
however, while traveling between the interatrial septum and
the ventricular muscle mass. This is because conduction
between atria and ventricles can only occur by way of the
A-V (atrio-ventricular) node and "bundle" (a specialized
conducting tissue). The only other tissue normally
connecting auricles with ventricles is connective tissue, which
does not have the property of conducting an impulse. This
results in the completion of atrial contraction before
ventricular contraction begins. During the period of
contraction and depolarization, action currents similar to
those in all muscles of the body can be sensed at the surface
of the body.
ENVIRONMENTAL INFLUENCE ON CARDIOVASCULAR
During routine daily activities, the force of gravity influences
the distribution of blood in the cardiovascular system and,
consequently, changes the nature of blood flow regulation.
Thus, the function of this system is dependent upon the
effects exerted by the Earth's gravitational pull.
to Lack of
The effects of null or diminished gravitational forces that are
experienced during space flight have not been fully
elucidated by past studies. However, flight observations
coupled with analyses of the cardiovascular system have
indicated the following potential problem areas when the
forces of gravity are altered.
Cardiac Contractility— Reduction in work performed by
antigravity muscles reduces the nutritive and waste removal
requirements imposed upon the cardiovascular system; herice,
the heart leads a more sedentary existence. One mechanism
by which it can decrease its total output is to reduce the
forcefulness of each contraction.
Vascular Responsiveness— Alterations in the responses of the
vascular smooth muscle, which occur with decreased
stimulation (hormonal, nervous, mechanical) with changes
in the contractile properties of smooth muscle cells, and with
alterations in vessel geometry caused by change in
intravascular volume, will result in qualitative and
quantitative changes in the cardiovascular function. In
particular, the vascular neural reflexes that compensate for
drainage of intravascular fluid away from the heart when a
man assumes an upright position in a gravitational field
become less effective. This situation, called orthostatic
hypotension, can develop after a few days in a weightless
state and upon return to Earth could lead to temporary bouts
of fainting because of inadequate brain circulation.
Capillary Exchange— Alteration in the transcapillary pressure
gradients or the properties of the capillary walls change the
quantity and the composition of the fluid that moves from
the intravascular into the extravascular spaces.
Viscoelastic Characteristics of Vessels— Changes in vascular
distensibility, especially that of the capacitance vessels
•' . (located principally in the venous circulation), markedly alter
the quantity of blood returned to the heart as well as the
time-dependent characteristics of venous blood return, and
thence, alter the output of the heart.
Decreased Endocrine Activity— Depletion of vasoactive Vasoactive— exerting an effect
hormone stores (e.g., norepinepherine) or decreases in their upon the blood vessels
rates of synthesis effectively limit or alter the ability of the
vascular system to respond to stress when the need arises.
Smooth muscle responses to given concentrations of
vasoactive hormones may also assume different patterns as
adaptation to a new environment occurs.
Decreased Vascularity— Both an enriched oxygen atmosphere
and a decrease in oxygen demands of tissues associated with
decreased work will reduce the oxygen transport
requirements placed upon the cardiovascular system. The rate
of oxygen diffusion through the tissue spaces to meet cellular
oxygen needs will become lower. Thus, the diffusion paths
can be lengthened without compromising these needs. Under
these circumstances, tissues become less vascular through a
relatively slow process of acclimatization.
Shifts of Intravascular Fluid Volumes — Volume receptors that
respond to vessel or heart chamber wall stretch are stimulated
by shifts of fluid within the vascular spaces when
gravitational forces are removed or decreased. Through
neuroendocrine pathways, a diuresis is initiated and the total
water content of the body is reduced. This results in partial
dehydration of body tissues and reduces the capacity to
respond to stress.
Nonspace Related Conditions— Consideration must also be
given to debilitating cardiovascular diseases and to other
Earth environmental conditions not unique to weightlessness.
The occurrences! of these are not precluded by weightlessness;
hence, long term comprehensive longitudinal studies on flight
crews and improved prediction models are required to
establish probability tables to assist medical support of long
The Skylab program incorporates two experiments that
provide information on the performance of the
cardiovascular system in the near weightless environment of
space. This infprmation will aid in establishing the relative
importance of the above problems for long-duration
Inflight Lower SKYLAB EXPERIMENT M092
(LBh^T EXPERIMENT BACKGROUND
Reduced orthostatic tolerance can be demonstrated by Orthostatic— pertaining to or
provocative (stimulating) testing during weightless flight. One caused by standing erect.
method of provocative testing involves the application of
lower body negative pressure (subambient pressure to the
body surface below the diaphragm). The equipment to apply
this negative pressure is the lower body negative pressure
device (LBNPD). Physiological indicators are heart electrical
activity, pulse pressure, blood pressure, heart rate and limb
The body stresses produced by LBNP on the cardiovascular
system of a supine subject in 1-g in certain respects closely Supine— lying on the back in a
resembles the effects produced by a normal upright posture, relaxed position
These stresses are an effective decrease in resistance to blood
flow to dependent portions of the body, and increase in the
level of venous pressure in dependent veins required to return
blood to the heart. LBNP results in pooling of blood in the
lower body hindering its return to the heart, and therefore
elicits a similar cardiovascular response to that experienced
during upright posture on Earth. LBNP thus provides an
objective means of provoking cardiovascular responses that
can be used to determine the extent of cardiovascular
deconditioning. The technique could conceivably serve as a
countermeasure to deconditioning due to the near weightless
environment, by providing periodic calibrated stresses that
may minimize the effects of spaceflight.
The objective of this experiment is to provide information
concerning the time course of cardiovascular deconditioning
during flight and to provide inflight data for predicting the
degree of orthostatic intolerance and impairment of physical
capacity which is expected following Earth return.
The major components of the experiment equipment used
1) lower body negative pressure device (LBNPD),
2) leg volume measuring system (LVMS),
3) blood pressure measuring system (BPMS),
4) body temperature measuring system (BTMS) (M171
5) vectorcardiograph (VCG) (M093 experiment equipment).
The LBNPD consists of a cylindrical tank with a waist seal
that provides positive isolation of the inner volume and lower
limbs from the ambient atmosphere. An inner crotch support
prevents the crewman from being pulled into the device by
the reduced internal pressure during operation'. This device
can be evacuated to a controllable pressure of 0-50 mm Hg
below the ambient cabin pressure.
The LVMS senses the changes in the circumference of the leg
at the level of the calf muscle by a capacitive type detector
leg band. Data signals from the leg band are then conditioned
and displayed on a console panel as percent volume change.
The BPMS includes an inflatable arm cuff and a microphone
for detecting the Korotkoff sounds characterizing blood flow
using , the auscultatory method. These pressures can be
displayed and/or recorded for transmission to the ground.
Each of the crewmen will participate in the LBNP tests at
approximately the same time each day, every third day
during the mission. A LBNP test will consist of a 5-minute
period of rest at 15 minutes of progressively decreasing
pressure on the lower limbs until 50 mm Hg (1 psi) below
cabin pressure is reached. This is followed by 5 minutes of
rest. Physiologic measurements are made throughout the test
A minimum of five measurement sessions are planned for
each flight crew at approximate intervals as follows: selection
of the crew, 60 days, 21 days, 10 days, and 2 days before
launch. These data will serve as both the experimental
control and the baseline reference for postflight data.
Korotkoff Method — to
determine blood pressure
method— listening for sounds in
the body to ascertain the
condition of the lungs, heart, etc
Postflight measurements will be made beginning as soon as
possible after recovery, at recovery plus 24 hours, and at each
24-hour interval thereafter until normal preflight values are
The principal measurements taken during the experiment are
1) pressure differential (AP across the chamber),
2) leg circumference (correlatable with leg volume),
3) blood pressure,
4) internal temperature (LBNPD chamber temperature),
5) cabin temperature (ambient temperature to the subject's
head, shoulders, and upper torso),
6) subject's body temperature,
8) heart rate.
SKYLAB EXPERIMENT M093
The excitation process in cardiac muscle is similar to that in
skeletal muscle and in nerves. It results in a propagated
depolarization of cell membranes described below and is
made evident by action currents. The electrocardiogram is a
graphic record of the action currents from the heart muscle;
These action currents may be recorded by placing pickup
electrodes at two locations on the surface ' of the body. At
any instant during the cardiac cycle the heart may be
considered as a battery with' the depolarized region of the
heart (through which the impulse has already passed at that
instant) acting as a negative pole, and the inactive region of
the heart' (through which the impulse has not yet passed)
acting as the positive pole. This Battery is immersed in an
electrically conducting medium, the body. Consequently,
action currents will flow, not only within the heart, but
through all the tissues of the body, including' those at the
surface. Hence, surface' electrodes may be used to lead off and
irecprd these ' potential differences as an index of cardiac
action currents. ■'" . ■■'■."'■ '
Vectorcardiogram— a graphic
record of the magnitude and
direction of the electrical forces
of the heart
Electrocardio- As the cardiac impulse spreads through the heart during each
gram heart cycle, the spatial and electrical relationships between
active and inactive regions of the hejirt are constantly
changing, thus causing the surface potentials to change from
moment to moment, both in magnitude and direction. Thesis
changing potential differences between lead-off points on the
body . surface, when graphically recorded, constitute the
electrocardiogram. ■ . '
Axis of the
The electrical condition of the heart at any instant may be
represented by a vector whose direction indicates the
orientation of the negative or depolarized portion of the
heart with respect to the positive or inactive region of the
heart at that instjant. The magnitude of this vector is
proportional to the instantaneous potential difference
between the positive and negative portions of the heart. This
vector, which undergoes cyclical changes in magnitude and
direction in space during each heart cycle, is known as the
electrical axis of the heart. The instantaneous potential
difference recorded between any two surface lead-off points
is proportional to the projection of the electrical axis upon
the line'joining these two points.
Electrocardiogram— a graphic
tracing of the electric current
produced by the contraction of
the heart muscle
Thus, a record taken from two points on the surface of the
body will provide information concerning the cyclical
variations of the electrical axis of the heart. More
information can be obtained by recording from several pairs
of surface points than can be obtained by recording from
only one pair. Hence, it is customary to record, in turn, from
three pairs of lead-off points known as the three standard
limb leads. Lead I is taken from the two arms, lead II from
the right arm and left leg, and lead III from the left arm and
left leg. (See Figure 4-2.)
Standard ECG Limb Leads
Typical ECG-Lead I (left arm-right arm)
Left Arm (LA)
Right Arm (RA)
Figure 4-2 Standard ECG Connections
If some portion of the hcEirt is injured as the result of
inadequate blood supply or some disease process, injury
currents will flow. These injury currents may appear in the
standard limb leads, but sometimes, if the injured area is
small, or if it is located in particular regions of the heart, the
injury current can be recorded only by applying one
electrode to the surface of the body as close to the heart as
possible, i.e., on the chest. Consequently, it is customary to
record, in addition to the limb leads, two or more chest leads
in which one electrode is placed on the chest and the other
electrode on an arm or leg. Additional leads are often taken
from the chest and sacral regions.
The form of the electrocardiogram recorded from any lead is
determined by the site of origin of the cardiac impulse, its
pathway of spread through the heart, the position of the
heart within the chest, and the presence or absence of injury
currents. This is simply another way of saying that the form
of the electrocardiogram is determined by the cyclical
variations in direction and amplitude of the electrical axis of
the heart and the point of attachment of the leads.
Cardiac Impulse — the impulse or
beat of the heart at the fifth
intercostal space at the left side
of the sternum
The form of the electrocardiogram for a typical normal heart
cycle is indicated in Figure 4-2. This curve is typical for the
limb leads; minor variations are seen in the chest leads. The
important characteristics of the curve are the P wave, the
QRS complex, the S-T segment, and the T wave. Important
time intervals are the P-R interval and the duration of the
The P wave results from the activation of the auricles. The
QRS complex results from the activation or depolarization of
the ventricles. The S-T segment occurs during the time in
which the ventricles are in the completely depolarized state,
and -the T wave represents ventricular repolarization. No
significance is attached to the U wave which is sometimes
A specialized form of the electrocardiogram called
vectorcardiogram (VCG) can be obtained by plotting one
channel against the other. Figure 4-3 shows a typical
arrangement for generation of VCGs. A cardiologist trained
in interpretation of VCGs can tell much about the activities
of the heart from such a display.
Typical VCG (leaps I & V^)
Figure 4-3 VCG Connections
Actually experiment M093 will analyze the three channels of
information on a computer to get the information needed.
Among the things that can be determined by an analysis of
yCG are the electrical orientation of the heart and its
movements. This experiment will analyze the VCG taken on
each of the nine astronauts who fly in Skylab both preflight,
inflight, and postflight. VCGs obtained while the astronaut is
at rest and at a number of exercise levels on the ergometer
will also be analyzed.
Ergometer — an instrument for
measuring the force of muscular
The objective of this experiment is to measure the
vectorcardiographic potentials of each astronaut periodically
throughout the mission so that flight-induced changes in
heart function can be detected and compared with a baseline
The equipment consists of the various electrodes and wires
for "picking up" the voltages from the astronaut's body and
the electronics equipment for amplifying the voltages,
protecting the astronaut from electrical shock, and
conditioning the voltages into the three channels of
The experiment is scheduled to- be performed every threei
days on each astronaut. The subject crew member attaches-
the VCG electrodes, rests on the ergometer for five minutes,
then pedals for two minutes at a set work rate of 150 watts. ^
He then rests for 10 minutes.
The data, recorded on tape to be telemetered to the nearest
ground tracking station, consist of the three standard vector-
cardiogram voltage signals and a heart rate channel, along with
voice identification of the conditions of recording.
Skytab Experiment MITI
The most basic process of living systems is production of
energy by metabolism. The energy derived from these
processes is used for physiological and biochemical functions,
permitting the organism to perform work.
When an individual is not moving or working and has not
recently eaten, all of the energy appears as heat. During this
condition, energy production can be directly measured by
direct calorimetry. However, this covers only a srnall portion
of the time when total energy measurements are required.
Energy Energy production can also be calculated using indirect
Production calorimetry which measures the oxygen consumed. Since
oxygen is not stored (except for about one liter as
oxyhemoglobin and myoglobin in the blood and tissues), its
consumption keeps pace with immediate needs and is
proportionate to the total energy produced. One problem
with using only oxygen consumption as a measure of energy
production is the fact that the energy released per mol of
oxygen is dependent upon the food being oxidized. Although
an estimate of 4.82 k cal/mol oxygen is accurate enough for
most purposes, the actual values can be determined from an
analysis of the respiratory quotient (RQ), which requires that
carbon dioxide production (during steady state conditions)
be measured simultaneously with oxygen consumption.
The measurement of energy production through the use of
indirect calorimetry has been accomplished clinically and in
the laboratory using two general methods— closed circuit and
open circuit. Excellent discussions of these two types of
measurement can be found (Cpnsolazio, et al. 1963; Best and
Taylor, 1961; Bard, 1961; Bartels, 1963.) In the closed
system the subject rebreathes from a container of 100%
oxygen and a carbon dioxide absorber. The oxygen
consumption is then determined by the decrease in volume of
the system or by the amount of oxygen added to keep the
volume constant. If carbon dioxide production is desired, the
carbon dioxide absorber must be weighed or analyzed, or be
assessed by a system that determines volumes before and
after carbon dioxide absorption. Luft (1958) has reviewed
spirometric methods which have been used for closed circuit
The standard open circuit method of determining metabolic
rate is based on minute volumes and gas concentrations.
Usually only expired volume (collected in a spirometer -
Tissot method; in a bag - Douglas method; or measured.with
a dry gas meter with a portion of gas being saved for analysis -
Kofranyi-Michaelis respirometer) is measured and analyzed
for its oxygen, carbon dioxide, and nitrogen content. From
these values it is possible to calculate inspired volume and
therefore Vq , Vqq , and RQ.
Calorimetry— measurements of
the amounts of heat absorbed or
If man is to be qualified for long duration missions, it is
imperative that energy metabolism data be collected in flight.
This is needed because of logistics and life, support
requirements, as well as the possible physiological
degradation of work performance.
Until inflight data can be collected, it is also required that
energy metabolism and work performance, as well as
pulmonary function, be evaluated pre- and postflight. Should
a physiological degradation of ability to do work be evident,
an acceptable limit of this degradation will have to be
established. These limits will be determined by required
activities for the successful completion of a mission,
considerations relating to the mechanism behind ' the
degradation, and whether countermeasures are possible.
Life Support The life support systems both in the spacecraft and the suits
for EVA operations must be adequate to accommodate the
functional work capacity (both sustained and transient
thermal loads) of the typical astronaut. While the work
capacity in the spacecraft is not likely to exceed that of an
aircraft pilot in the geogravitational environment, this cannot
be said of EVA operations, where an emergency may raise
the metabolic level to that experienced during heavy exertion
on Earth. Fletcher (1964) has compiled data from several
sources (Figure 5-1), to show metabolic curves for first class
athletes and healthy men engaged in exerting activities
(running, rowing, cycling, etc) under normal atmospheric
conditions. The design criteria for the life support systems
for EVA operations should be such as to permit the levels of
activity shown by Fletcher, thus providing for those
emergencies which call for. these higher metabolic levels.
EVA— extravehicular activity
0.25 1 3 5 10
Btu " Kcal
2.0 "1 12,000-- 3,000
6 8,000-- 2,000
1-0 S 6,000
Figure 5-1 - Maximum Sustained Work Capacity
SKYLAB EXPERIMENT Ml 71
Metabolism has been an area of investigation from the first
manned missions. During the Gemini Program in the mid 60s,
a number of the medical investigations were concerned with
metabolism. Many tests were performed to determine
whether the crew would become fatigued doing the types of
activities that had been planned, and whether the life suppoi^
system in the spacecraft and in the space suit would be able
to meet the astronauts' requirements. During these early
missions, it was learned that there were some significant
problems. The astronauts became much more fatigued than
had been expected, tasks were much harder to perform, and
the possibility arose that under certain conditions the carbon
dioxide levels in the space suit rose to higher than desirable
levels. Problems with the design of equipment and the work
regimens specified for the astronauts were discussed. These
concerns and investigations continued into the Apollo
Program, and still many questions remain to be answered.
Of particular interest is the relationship between the
metabolic requirements of certain physical tasks in space
compared to the requirements for the same tasks on Earth. A
common means of determining these requirements is to
ascertain the oxygen consumption and carbon dioxide
production of the body during the performance of the
These consumption and production rates cannot be measured
directly at the cellular level where the demand exists.
Measuring intake and output for the body as a whole is
considered to represent the aggregate demand for all cellular
activity. Consumption and production are usually called
oxygen uptake and carbon dioxide output. The former is
determined by measuring the amount of oxygen that a
person breathes in over a given period of time and subtracting
from it the amount of oxygen that he breathes out over the
same period of time. The latter is determined similarly: the
volume of carbon dioxide breathed in over the period is
siibtracted firom the voluine of carbon dioxide breathed out
over that same peiriod. For certain types of exercise, the
oxygen uptake is equal to oxygen consumption and carbon
dioxide output is equal to carbon dioxide production. By
properly planning an experinient, the oxygen consumption
and carbon dioxide piroduction can be determined from the
oxygen uptake and carbon dioxide output measurements
(along with other supportive measurements and information).
By doing such determinations while a subject is performing a
measured amount of physical work, the relationship between
metabolic activity and the physical work can be determined.
Metabolism— the sum of all the
physical and chemical processes
by which living organized
substance is produced and
Such measurements are commonly done in the laboratory
taking the measurements yvhUe the subject is performing
work on a treadmill or an ergorneter, each of which is a
means of providing known ^mounts of physical work for the
individual to do. '
The objectives of this experiment are to determine if man's
metabolic effectiveness in doing mechanical work is
progressively altered py exposure to the space environment,
and to evaluate the bicycle ergorneter as an exerciser for long
Measurements Five major pieces of equipment are used for this experiment.
1) Metabolic Analyzer determines the oxygen update for
one minute and five minute periods; carbon dioxide
output for one minute and five minute periods; minute
volume, the total gas expired by the subject during a
one-minute period; respiratory exchange ratio, the ratio
of carbon dioxide output to oxygen uptake; and vital
capacity, the measurement of the maximum amount of
gas that a person expires after a full inspiration.
2) Ergometer, a controllable workload pedal device, having a
workload selector and tachometer. The pedals connect to
the workload which offers mechanical resistance set to a
desired level. The ergometer measures work rate, the
actual work rate which the astronaut performs on the
ergometer; revolutions per minute, the rate at which the
astronaut pedals the ergometer; and total work
performed during a given period.
3) Body Temperature Measuring System electrically
measures the temperature in the subject's mouth using an
4) Vectorcardiograph senses three channels of electrical
signals from the heart and permits heart i:ate to be
5) Blood Pressure Measuring System comprises a
microphone and inflatable arm cuff.
Thermistor — a special type of
resistance thermometer that
measures extremely small
changes in temperature
The metabolic activity experiment will begin 12 months
before flight. The experiment will be repeated at one-month
intervals from '6 months before launch and also 5 days before
flight. Inflight the experiment will be repeated five tirhes by
each crewman during the, 28-day flight, and eight times
during the 56-day flight. After recovery the exercise capacity
test will be performed oh each crewman as soon as possible
after recovery and again after 24 hbuirs. If there are any
significant changes in hietabolic performance during the
course of the rhissiori, these cHanges will be followed until
baseline levels are reached.
Work profiles for this experiment include (1) the subject
remains relaxed and motionless for 5 minutes, (2) he then
pedals for five minutes with an energy output fixed at 25% of
his preflight dietermined rnaximum capacity; (3) the work
rate is changed to 50% of his preflight maximum capacity,
and the subject operates the ergorheter at this rate without
interruption for another five minutes; (6) the work irate is
changed to 75% of the preflight determined maximum
capacity and operated at this rate for five minutes; (7) the
subject stops the ergometer, relaxes, and remains motionless
for 5 minutes.
The data retiirn from this experiment will consist of the
profiles that occur during a prescribed exercise regime in zero
gravity for the following variables: blood pressure, heart rate,
vectorcardiogram, and metabolic rate. The metabolic rate is
computed from measurements of oxygen consumption and
carbon dioxide piroduction. The data derived from this
experiment are recoirded on the spacecraft tape recorder and
transmitted to ground. Manual data recording is available as a
backup mode. Voice comments are also recorded. Motion
picture data will be obtained using a 16mm camera.
Human Vestibular Function,
Sky lab Experiment Ml 31
Skylab Experiment Ml 33
pagf; btank ^ot nmm
The physiology of the nervous system in man is complex,
ranging from the sensing and processing of input information
via the afferent nervous system, to the higher order
neurological functions haying a poorly understood
neurophysiological basis, e.g., language, learning, and states
Two investigations being conducted oh Skylab will evaluate
aspects of the central nervous system and the impact of
weightlessness. The first, an experiment involving the human
vestibular apparatus, will investigate the effects of
weightlessness on the crewman's ability to niaintaih
perceptual acuity and orientation in sp^ce. This experiment
will identify changes in the normal functioning of the
vestibular apparatus after long periods of weightlessness.
The second investigation will use the electroencephalogram
(EEG) in an attempt to evaluate the sleep patterns derived
from the brainwaves in the space environment. This
experiment should establish whether there are changes in the
sleep quality or quantity associated with extended flights.
SKYLAB EXPERIMENT M131
Body position and movement is perceived principally by
specialized sense organs in the inner ear, collectively termed
the vestibular apparatus or the labyrinthine receptors. These
organs are the otoliths and the semicircular canals. The
otoliths are stimulated by linear accelerations (including
gravity) and are the specialized organs for the sensofy
perception of head tilt relative to the direction of the local
force field. The semicircular canals sense the magnitude and
direction of angular accelerations. The brain integrates these
sensory data inputs to determine and maintain the body's
posture and orientation.
The importance of the vestibular organs in day to day
activities Isecomes apparant if one considers their
neuroanatomical connections to the-
1) reticular system, dealing with alertness and attention,
2) eye muscles,
3) aiitonomic nervous system, dealing with regulation of
respiration, heart rate, GI tract motility, etc,
4) voluntary and anti-gravity body muscles, and
5) cerebral cortex.
Cerebral CJortex— the convoluted
layer of gray substance that
covers each cerebal hemisphere
Experimentally produced discrepancy between visuEil,
vestibulai:, and tactile-kinesthetic spatial perceptions have
been shown to cause a stressful sensory conflict which,
depending on the individual, produceis symptoms ranging
from disorientation to nausea and vomiting.
Varying degrees of discomfort and disorientation have also
been noted under conditions of near weightless spaceflight.
During the first American orbital flight (MA-6, February 20,
1962) Astronaut Glenn in his pilot report noted that he had
experienced an illusion of tumbling forward after cessation of
the initial acceleration of his vehicle and entry into the
weightless environment. He also noted a false sensation of
accelerating in a direction opposite to retrorocket firing
Astronaut Cooper, referring to his Mercury Flight (MA-9,
May 15, 1963), has been quoted as having felt
"... somewhat strange for the first few minutes. . ." after
which he "readily adapted" and felt "completely at ease."
Later in the mission, following a short nap, he is quoted as
awaking "with no idea where I was and it took me several
seconds to orient myself." He also stated that, with respect
to sleep, "you have trouble regrouping yourself for a short
while when you come out of it." He had an experience,
similar to Astronaut Carpenter's on an earlier flight (MA-7,
May -24, 1962), when the cockpit seemed to be "somewhat
differently located in respect to myself," upon onset of the
weightless state. He felt, during the early part of the first
orbit, a moving forward in the seat in spite of tightly fastened
restraint straps, and the equipinent storage kit on his right
seemed at a different angle relative to him than when on the
launch pad. He felt that he was sitting upright although he
later described a feeling of hanging upside down because of
pressures against his shoulder straps.
The sensation of hanging upside down from their restraint
straps was also noted by Russian Cosmonauts Yegbrov and
Feoktistov (VOSKHOD 1, October 12, 1964) but were
similarly brief and always disappeared upon the onset of
reentry acceleration. Cosmonauts Gagarin (VOSTOK 1, April
12, 1961), Titov (VOSTOK 2, August 6, 1961) and Popovich
(VOSTOK 4, August 12, 1962) also briefly experienced this
inversion illusion during their space flights but the
phenomenon was reported to have had no effect on their
A more significant feature of early Russian spaceflight
experience was the apparent motion sickness syndrome
reported by Titov during VOSTOK 2. After five or six orbits
he noted symptoms of decreased appetite, giddiness, and
nausea which were aggravated by sharp head movements and
reduced by keeping his head still. In spite of the fact that the
vehicle was probably rotating slowly and that repeated head
movements comljined with anxiety and the initial inversion
experiences could theoretically account for the problem, the
results were interpreted, as from a direct
"otolithic- vegetative" disorder. Subsequently, a great deal
more investigation and training was devoted to the
labyrinthine and proprioceptive systems in the Soviet space
effort with somewhat ambiguous results. Symptoms as
dramatic as Titov's were not again reported until the flights
of Apollo 8 and 9, although temporary motion sickness was
apparently experienced in a milder forrh by both Fedktistov
and Yegorov. The eight Eind. fourteen days of Gemini V
(August 21, 1965) and Gem,ini VII (December 4, 1965),
respectively, produced no such symptoms in the four U. S.
astronauts involved, although they experienced an increased
gravity sensitivity during retrofire and reentry. This apparent
form of increased vestibular sensitivity disappeared
Labyrinth — a system
canals, such as the inner ear
Pr opri oceptive— receiving
stimulations within the tissues of
Finally, the nausea and vomiting that occurred during the
Apollo 8 and 9 flights was almost certainly caused by
vestibular system malftanctiohs. The relationship between
these symptoms and the greater freedom of intravehicular
movement in the Apollo CM deserves careful attention.
Areas of In-
Because of the inability to produce conditions of prolonged
weightlessness on Earth, at least two major areas of vestibular
investigation are necessary for the qualification of man in
long duration space flight:
1) Ensure that permanent otolithic changes attributable to
spaceflight conditions do not occur;
2) Ensure that temporary vestibular disturbances will hot
occur inflight that will inteirfere with crew safety and
These areas are also significant to the study of man's
adaptation to rotating space vehicles and artificial gravity
The experimental approach in Skylab uses a healthy^
well-trained subject adapted somewhat to the unusual
vestibular stimuli he has experienced as an aviator in the
flight phase. Control groups have been selected so as to
include some known vestibular defectives. In one test, the
measurement of angular acceleration threshold, a rotating
chair device will be used to provide the subject stimuli of
physiological character, at best unusual in a subgravity
environment, and a test goggle to measure oculogyral illusion.
Oculogyral illusion, the most sensitive indicator of threshold,
is a form of apparent motion that has its genesis in the
cupula-endolymph mechanism and may be viewed under
many different circumstances. The test goggle used provides
the favorable conditions of dimly lighted three-dimensional
target viewed in darkness and fixed with respect to the
subject. The expected apparent motion of the target is in the
direction of accleleration.
In another part of the experiment, provocative tests will serve
to evaluate the subject's susceptibility to reflex vestibular
disturbances and to motion sickness and may, in addition,
measure his abihty to cope with such disturbances. These
tests will measure the coriolis sickness susceptibility index
using, again, the rotating chair but with the subject making
standardized head motions out of the plane of rotation.
A unique feature of this test is the method of scoring the
investigators have developed. This highly effective method
yields a single value, the index, enabling the investigator to
make comparisons within and among test subjects. The level
of severity pf acute motion sickness will, therefore, Jae
absolutely controlled to a definite end point defined as
Malaise IIA. (See fable 6-1). The test end point will be fixed,
while the level of stresses required to reach that end point
will be measured (number of sequence of head motions and
Table 6-1 Diagnostic Categorization of Different Levels of Severity
of Acute Motion Sickness
Headache > II
closed ^ II,
eyes open III
Levels of Severity Identified by Total Points Scored
*AOS = Ac
Iditional qualifying symptoms I = moderate,
I = severe or marked, II = slight.
Epigastric— pertaining to the
upper middle region of the.
abdomen, located virithin the
Spatial The spatial localization experiment uses the rotating litter
Localization chair in the static tilt and litter modes, together with the
otolith test goggles, blindfold, and a reference sphere and
magnetic pointer. The astronaut's capability to determine his
orientation is tested with the chair upright as well as tilted.
The subject is first tilted to various positions relative to the
spacecraft with his eyes closed and is asked to indicate both
his perceived direction of gravity and body orientation. He
indicates this both by setting the direction of an illuminated
line in the test goggles and by lining up a magnetic indicator
rod on a handheld sphere.
In the litter mode, the reference sphere and magnetic pointer .
and blindfold are used. Tests will investigate orientation
based upon a sensed g-vector provided by external reference
cues and internal reference cues. The chair is converted to a
litter and the subject attempts to align the magnetic pointer
to an external reference while blindfolded. Settings are made
with the litter in a horizontal position and with the litter in a
The objectives of this experiment are to acquire data to
validate measurements of specific behavioral and
physiological responses as influenced by vestibular activity
under Earth gravity and in free-fall conditions. These studies
are also expected to determine the crewman's adaptability to
unusual vestibular conditions, and to predict habitability
requirements for future spacecraft which may be rotated to
generate an artificial gravity force leading to unusual coriolis
forces. Another objective is to measure the accuracy and
variability in the crewman's judgment of spatial coordinates
based upon abnormal receptor cues and inadequate visual
Coriolis Forces— a fictitious
force used to describe motion
(aircraft or cloud formation)
relative to a noninertial,
uniformly rotating frame of
The equipment for this experiment consists of--
1) rotating litter chair,
2) proximity device,
4) otolith test goggle (with a biteboard mounting),
5) reference sphere with a m^netic pointer.
The rotating litter chair is a precision motor-driven
servocontrolled, rotating chair which can be tilted in two
directions or converted to a litter; however, it is only rotated
in the upright position.
The right eyepiece of the otolith test, goggles contains a
seif-illuminated target with pitch and roll adjustment. The
target is a slit of light that can be rotated to indicate a roil
position; a Break in the middle indicates the pitch position;
and ,a secontl small break at one end indicates polarity. The
target, the only thing visible to the subject, is illuminated by
a radioactive source in the goggles.
The otoiitH test goggle is fastened, to the chair so that when
the subject .bites on a biteboard and the gogglies are properly
adjiisted, the head wUl be held in the correct position for the
test: .- ,. ".-,'• - ■ ■
THe reference sphere with magnetic pointer is a device for
rneasuring spatial localization' using nonvisual clues. A
magnetic pointer is held against the reference sphere and
moved by the subject. The subject's judgments are nieasured
by a three dimensional readout device that allows free
Motion Each of. two crewinen will participate in dynamic vestibular
Sensitivity tests consisting of motion; Sensitivity tests iising the rotation
litter chair in the rotating nibde to cletermine susceptibility
to coriolis forces as a function of tirrie ih. weightlessness, and
to measure serriicircular . canal response thresholds by
conducting oculogyral illusion (OGI) threshold tests.^ This Oculogyral— pertaining to
sequence will be done on .5 equally spaced occasions during movement of the eye about the
the first 28-day mission. Each test sequence requires anteroposterior axis
approximately 30 minutes per crewman.
Each of three crewmen will participate in spatial localization
tests using the otolith test goggles and the rod and sphere
device. These tests will be performed once early in the
mission,, once in the rniddle of the mission, and once late in
During motion sensitivity tests:
1) test subject symptomatology in accordance with Figure
6-1 for determination of tirrie course of symptom
developrhent to the test end point;
2) experiment data pertaining to chair velocity, direction,
head motion characteristics, and experimental equipment
During oculogyral illusion tests:
1) oculogyral illusion response;
2) stimulus characteristics— chair acceleration, velocity and
3) experimental equipment performance data.
During spatial localization tests:
1) accuracy of subjects spatial localization and test
conditions (subjects actual orientation relative to the
space labs spatial coordinates).
Motion picture films of the experiment performance in all
modes will be obtained.
Sleep SKYLAB EXPERIMENT M133
One of the most dramatic and fundamental ways in which
the behavior of a mammal can change is in its state of
consciousness. There is a spectrum of changes from alertness
through quiet resting to drowsiness to various kinds of sleep.
These changes in states of consciousness affect the activity of
the nervous system in many ways. In the last few years our
understanding of states of consciousness has increased (and
One way of examining what is going on in the brain is by
means of an EEG (electroencephalograph). The EEC is a
recording of the electrical activity from the cerebral cortex.
It is clear, that the EEG is not just due to action potentials in
cells, although these probably contribute. Synaptic currents Synaptic— pertaining to the
play the largest part. There are good correlations between the anatomical relation of one nerve
EEG and states of consciousness. <=^" *° another
During alert, attentive activity the EEG is "low voltage, fast"
i.e., waves of less than 100 microwatts recorded from the
surface of cortex with frequencies mostly greater than 15 Hz.
When the subject is in a relaxed state, cpnscious but not
attentive to anything, the EEG has an alpha rhythm. The
alpha rhj^hm has a frequency of 8 Hz and amplitude of up to
400 microwatts. As the subject becomes more drowsy, the
frequency becomes slower. This is mixed with bursts of
electrical activity at 10 to 14 Hz lasting a few seconds. In
some kinds of sleep, the EEG waves are 2 to 3 Hz and about
400 microwatts. However, in another kind of sleep, the EEG
is low voltage, fast, almost exactly as in the alert state. AU
mammals demonstrate this same pattern although the exact
frequency is somewhat different from animal to animal.
The arousal mechanism subserves attentive alert behavior and
the associated EEG pattern. There is an anatomical site that
governs this activity, the reticular formation of the
mesencephalon (in the upper brain stem) and the adjacent
posterior parts of the hypothalamus. This is sometimes called
the reticular activating center. Electrical stimulation of this
site causes the animal to become alert, a response that will
last longer than the duration of the stimulus. Destruction of
this center produces coma. Among the normal inputs to this
center are those from all the sensory systems. A single cell in
this center may be fired by a flash of light, a ringing bell, a
touch on the skin, or a smell. It is polysensory. This makes
sense in terms of the function of the center, for any kind of
sensory stimulation, if sufficiently intense, will cause an
animal to become alert.
There are many aspects of arousal. The musculature increases Muscul ture— the muscular
its tone, and the cardiovascular system is affected. With apparatus of the body, or any
arousal the sensitivity of most aspects of sensory systems is P^* ** '*
decreased. This may seem paradoxical, but this eliminates
irrelevant inputs and presumably allows greater attention
toward specific sensory inputs. There is no simple
interpretation of the effects of arousal on the activity of the
cerebral cortex. Some cells fire more, some less; some are
more excitable, some are less excitable.
There are two kinds of sleep. One kind, which we will call
slow wave sleep, comprises about 75% of sleeping time. The
other kind of sleep, which we will call paradoxical sleep, in
humans comes in episodes of 10 to 20 minutes duration
every 30 to 90 minutes and comprises about 25% of sleep.
(Paradoxical sleep is also called rapid eye movement sleep or
REM sleep.) Paradoxical sleep can only be reached by going
through slow wave sleep.
Paradoxical Paradoxical sleep is very stereotyped. It starts abruptly, it
Sleep involves a loss of tone in muscles, except those of the face
and eyes. The facial muscles twitch and there are rapid
movements of the eyes. The blood pressure decreases. The
EEG is low voltage fast frequency. If a human is awakened,
especially during the early st^es of deep sleep, he will
usually report a dream. If an animal is awakened as soon as
an episode of paradoxical sleep begins, another episode of
deep sleep cannot start again for at least 30 minutes. If
animals are awakened whenever they begin to have an
episode of deep sleep, because of this "refractory period,"
they can be prevented from spending much time in
paradoxical sleep, although their total sleeping time remains
normal. All animals, after being deprived of paradoxical
sleep, show an increased proportion of paradoxical sleep the
next time they sleep.
A center for paradoxical sleep has been found in the pons
(part of the brain stem). Stimulation of this site initiates
paradoxical sleep; destruction of the site prevents paradoxical
sleep. Norepinephrine, which is presumed to be a synaptic
transmitter substance, is concentrated in these areas and
appears to be very much involved in pciradoxical sleep.
Slow Wave Slow wave sleep (non REM or NREM) can be initiated by
Sleep stimulation of many parts of the brain. Many other sites
initiate slow wave sleep if stimulated at about 8 Hz, even a
peripheral nerve. Slow wave sleep, unlike arousal and
paradoxical sleep, seems to require that the cerebral cortex
be present. However, a major contribution to slow wave sleep
comes from the medulla (part of the brain stem). Serotonin, Serotonin— a constituent of
which is presumed to be a synaptic transmitter substance, is blood platelets
concentrated in these areas and appears to be very much
involved with slow wave sleep. If a barbiturate general
anesthetic is injected into the blood going to the posterior
brain's stem (i.e., to the pons and medulla) the animal will
wake up. If the anesthetic is allowed to go to the more
anterior part of the brain the animal will be anesthetized,
which is similar to slow wave sleep in many ways. Slow wave
sleep and alert behavior are part of a continuum. There are
many intermediate stages. Paradoxical sleep, however, is all
or none, with no intermediate stages.
It would appear that there are three active mechanisms
involved in states of consciousness. Sleep is not just the
absence of consciousness.
The blood flow and oxygen consumption of the brain is the
same in arousal and slow wave sleep, but is increased in
paradoxical sleep. There have been a few experiments in
which recordings have been made from the same nerve cell
while the animal was spontaneously awake, and then asleep.
Some neurons fire more during sleep, some less. Most
neurons fire more during paradoxical sleep. Therefore, the
brain does not rest in sleep. In fact, it is most active in
paradoxical sleep, and it is resting when it is awake. The
common sense view and the scientific view until about 1963
was that the function of sleep was to rest the brain. Today
we are not certain as to what the function of sleep is, but we
do know that it is essential to physical and psychological well
From the beginning of the space program there has been
considerable interest in whether the astronaut was getting
adequate sleep. In order to answer this question NASA has
been investigating the use of the EEG for inflight monitoring
of sleep. These investigations include determination of the
minimum number of brain areas from which signals that yield
useful information are picked up, and whether an onboard
computer can be used for performing the analysis, thus
reducing the complexity of the telemetry system that is
needed to return data to Earth. A preliminary approach to
the problem was undertaken to 1965 and continues to the
present time under the direction of the Principal Investigator
for this experiment.
The primary goal will be to monitor the sleep status of a
spacecraft crewmember during selected periods throughout
an extended space mission, utilizing automatic onboard
analysis of electroencephalogram (EEG) and
electro-oculograph (EOG) with telemetry of results. Sleep
profiles will thus be available in the Mission Control Center
and may be readily evaluated in order to detect any
alterations in sleep quantity or quality.
The major components of the experiment equipment are:
1) cap assembly,
2) preamplifier and accelerometer assembly, and
3) control panel assembly.
The cap assembly precisely fits the astronaut's head and
correctly positions seven electrodes, which are part of it. The
electrodes are funnel-shaped, soft "rubbery" devices
containing electrolyte soaked sponges. The lower portion of
each electrode is cut off by scissors just before the crewman
puts on the cap, thus exposing , the electrolyte for proper
contact with the scalp. A new cap will be supplied for each
experiment sleep period.
Three consecutive nights of sleep recording will be required
of the prime and backup crewmember within 60 days before
launch, plus a one-hour session in the Principal Investigator's
A total of 15 selected sleep periods shall be recorded during
the first (28-day) mission, and 21 sleep periods during the
second mission (56 days).
Three nights of sleep recording aire desired oh postflight days
1, 3, and 5, using the same procedures arid basic equipment.
The procedure for this experiment is quite simple. On the
specified nights, before retiring, the astronaut takes a cap
assembly, cuts the tips off of the electrodes, connects the cap
assembly to the rest of the equipment, dons the cap, and
secures himself in the sleep restraint. After checking the
operation of the equipment he goes to sleep in a normal
manner. As he sleeps the equipment automatically performs
the analyses and provides data to the telemetry system. Upon
awaking he disconnects the equipment, throws away the cap,
and makes any comments needed in the log and to the voice
1) Copies of all data tapes obtained during preflight and
postflight baseline testing will be provided to the
Principal Investigator for analysis.
2) A log entry is required after each monitored sleep period,
preflight, inflight, and postflight. This entry, made by
voice recording, will contain information on the duration
of sleep, quality of the sleep, and any medication used by
the subject with 24 hours before the beginning of the
monitored sleep period.
Effects of Zero Gravity on Single Human Cells,
Skylab Experiment SOI 5
Circadian Rhythm-Pocket Mice,
Skylab Experiment S071
Circadian Rhythm-Vinegar Gnats,
Skylab Experiment S072
Biological Many biological processes of living organisms are periodic in
Processes nature. The most well known of these are the circadian
(daily) rhythms of sleep, body temperature, flower petal
movements, etc, but there are many other biological
oscillatory frequencies as well. These rhythms are believed to
be evolutionary in origin and responsive to terrestrial cues
such as light/dark cycles. During manned space travel beyond
his evolutionary environment, temporal factors will have to
be included as part of the provided environment to avoid
breakdown of periodicities. Although work/rest schedules
may be the governing input, there are basic biolo^cal
questions related to circadian rhythms that may be of
It is possible to divide circadian rhythm research into four Circadian— pertaining to a period
categories: (1) occurrence and general characteristics, (2) of about 24 hours
environmental phase-setting, (3) the basic mechanism, and
(4) the importance of these rhythms to the organism.
To summarize briefly: (1) from unicellular organisms to man,
there are few biological processes that do not demonstrate
periodicity; and (2) circadian processes have a labile temporal
relationship wdth the environment and can be phase-set
(entrained) with appropriate light or temperature stimuli.
The latter two aspects, however, have • evaded scientific
inquiry, although many investigators are attempting to
determine the mechanism of circadian rhythms and the
physiolo^cal consequence of their disruption.
Circadian rhythms, rather than being direct biological
responses to the immediate temporal environment, may serve
a more basic role in the functioning of living systems.
Processes must occur not only at the proper place and in
sufficient quantity, but must also occur at the proper
time. Thus, the circadian mechanism permits interval
synchronization of an organism's processes and at the same
time synchronizes the total organism to its environment.
A review of the literature on human circadian rhythms shows
over 50 physiological variables with significant circadian
variations. Although this variation is only a small percentage
of the total change for a function such as vital capacity, it
accounts for the majority of the variation in others such as
electrolyte excretion. The circadian changes observed are
often caused by variations in other processes. Thus, it is not
always possible to determine the direct relationship between
the observed rhythm and the basic causal mechanism.
Changes in circadian rhythms may occur during certain
pathological conditions. In addition, there may be decreased
psychological performance associated with changes Dysrhythmia— disturbance of
(dysrhythmia or desynchronization) in circadian rhythms, rhythm
This phenomena is becoming a well-known effect of rapid
travel across several time zones.
There are two theories regarding the basic mechanism of
circadian rhytiims: (1) they are the result of a completely
endogenous mechanism (biochemical or biophysical
oscillator) with other environmental factors, such as light or
temperature, acting as phase-setters; and (2) they represent
an organism's response to subtle geophysical fluctuations
(such as magnetic fields) with li^t and temperature again
acting as phase-setters between the basic mechanism and the
The majority of investigators subscribe to the first theory;
however, the required critical evidence has not been
collected. The Skylab Program offers an environment in
which the two hypotheses can be tested, since during orbital
flight the geophysical variations are no longer available to the
organism on a 24-hour basis, and during interplanetary flight
they should be completely absent or greatly distorted.
At present, there is only suggestive evidence of detrimental
effects due to disruption of normal rhythms in abnormal
temporal environments. To date, it has not been possible to
completely abolish circadian rhythms, only to perturb them.
If the second hypothesis proves to be true, a completely new
factor will have to be considered during long duration flights,
i.e., the lack of a basic temporal coordination mechanism.
on Single Hu-
SKYLAB EXPERIMENT S015
A great deal is known about the behavior of human cells in a
1-g environment; both normal and abnormal behavior is well
understood. However, virtually no information exists on the
behavior of cells in a near weightless environment.
This experiment to study the influence of weightlessness on
living human cells is designed to obtain information on cell
development and propagation by using two different and
The first method will be through observation of two living
cells using microscopes and cameras. These cells will be kept
alive for the entire mission and returned alive. The cell
behavior will be periodically recorded during the mission.
This technique, using phase contrast microscopes (specimen
does not have to be stained) and time-lapse photographs will
allow postflight study of the visible portions of a cell.
Examples of this will be changes in ceU size, cell division
(mitosis), and changes in size and movement of specific
particles in the cell (oi^aneDe). Kidney cells will be used
because they flatten out in the specimen chamber so that the
nucleus and other particles are easily seen under a low power
Chemical The second method will deal with the chemical properties of
^°P^J^'^® cells and will be conducted during periods of rapid growth
rate. This portion of the experiment will be completed on the
fourth and tenth days of the mission, at which time the cells
are fixed and will be held in that condition until they are
returned for ground analysis.
The cell chemical study will use 24 separate embryonic lung
cell cultures. The cells will be allowed to grow for four days
and ten days, respectively, after the start of the mission. On
these days various radioactive materials tliat can be
assimilated by the cell will be introduced into sorhe of the
specimen chambers at specific times and for specific
durations. This will mark or label various functions of the
cells at that psirticular time. After the cells have been labeled,
excess radioactive material will be rinsed from the chamber
and all of the cells preserved with a fixative that will hold
them in that state until they are returned for ground analysis.
The information that will be gained from this portioh of the
experiment will be (1) the distribution of chemical
components in the cell (histochemical), (2) the amounts and Histochemical— chemistry of
rates of synthesis of various chemical constituents, and (3) tissues
the ultra structure, or arrangement of the very smallest
elements of a cell.
This experirrient will determine effects of near weightlessness
on living human cells in a tissue culture.
The expeiiment package consists of two major subsystems
both " enclosed in a single hermetically sealed package— the
microscope-camera subsystem and the biopack subsystem.
See Figure 7-1 for a simplified block diagram showing the
functions of the experiment.
The biopacks and the microscope-camera subsystems are
contained in a hermetically sealed experiment package which
also includes two clocks that control the automatic
operations. The two biopacks are enclosed in another
hermetically sealed container within the experiment package.
Media Label Rinse Label
Pressure Shell -
Figure 7-1 Simplified Schematic of Human Cell Experiment
The 20X and 40X power microscopes shown in Figure 7-1
have exposure lamp assemblies that project an image down a
light-tight tube to a mirror and film gate assembly. The image
is reflected on the film or in a viewport for ground checkout
when the mirror is manually rotated 90 degrees. The viewing
mechanism is used only for ground checkout and is
spring-loaded to prevent the mirror from being inadvertently
left in the viewport position after ground checkout. No
further adjustments are made in flight.
Each camera assembly operates independently and is
controlled by separate- internal clocks. Both cameras use
16mm film for recording microscope images of the cells.
The two camera asseniblies operate identically. One camera
photographs time-lapse motion pictures of images from the
40X magnification microscope. The second camera
photographs im^es 'from the 20X microscope. A removable
film pack is used to contain the 16mm film that is required
for each camera. The two" films travel in opposite directioris,
thereby maintaining a constant center of gravity.
Two separate specimen chambers, one for each microscope,
will provide a temperature-cori trolled environment in. which
the cells can live.
Each specimen chamber has an independent media exchange
assembly to provide firesh nutrients to the living cells. Twice
Time-Lapse Photography — a slow
and continuous process at
each day (not concurrently with the photographing period)
fresh nutrients are forced into the specimen chamber and
Each of the two specimen chambers contain two thin glass
coverslips with a molded rubber gasket held between them.
The specimens are attached to the inside of the coversUp
nearest the objective lens. Two tubes are attached to the
coversUp for supplying nutrients, and removing waste
material from the space between the coverslips. Each
specimen chamber has a media pump assembly. This pump
consists of a cylinder, a piston and a lead screw. Twice daily
the lead screw is turned one revolution to advance the piston
a short distance into the cylinder. This action forces fresh
media into the specimen chamber and waste media to the
return side of the pump.
The biopack subsystem consists of two independent
assemblies enclosed in a sealed container inside the
experiment package. Each assembly controls 12-ceU
chemistry experiments and each assembly contains 12 ceD
chambers, a motor drive assembly, a pump for providing
fresh nutrients and removing waste from the cells, and
provisions for lalDeling, rinsing, and fixing the cell cultures
whenever commanded by a crewmember.
The filming of the living cells is performed automatically.
The crewman has to check only for the proper operation of
the camera indicator lamp for the first 10 days. In the other
part (chemical properties) of the experiment, the crewman
will operate the experiment manually at the 4- and 10-day
points to perform the radioactive fluid labeling activities.
During the mission, the experiment package must not be
subjected to temperatures above 95° F or below 50° F, or to
radiation x-ray sources strong enough to damage the film.
Time-lapse motion pictures of the cell activity, as seen
through the 20X and 40X magnification microscope, wUl be
made and the results of the cell chemical analyses will be
published in study reports, possibly early in 1975.
SKYLAB EXPERIMENT S071
If the stability (precision) or the period of physiological
rhythms of small mamiiials change significantly during flight,
then there is a strong indication' that biorhythms of animals
on Earth are timed by some factor (or environmental force)
which is absent or significantly altered in space. This change
in the behavior of pocket mice, along with similar evidence
from the vinegar gnat circadian rhythm experiment, would
imply that weightless spaceflight alters the functioning of
basic control mechanisms for metabolic activity. The
maintenance of normal biological rhythms in man during
spaceflight is important to his well-being and effectiveness in
space. Insofar as we can assume a common response in
mammalian function, if the pocket mice in space continue
their terrestrial biorhythms, then we can conclude that space
conditions impose no stress on the basic biological clock
mechanism and, that man's performance will not be degraded
because of rhythm disturbances.
The objective of this experiment is to study the circadian
rhythms of body temperature and activity in pocket mice
(genus, perognathus) in an environment of constant
temperature, pressure, and total darkness, and in the absence
of geophysical variables within a 24-hour period.
The experiment consists of a sealed animal enclosiire coupled
to an environmental control system. The animal enclosure
contains six isolated mouse cages, the biotelemetry receivers,
and monitoring detector circuitry. The environmental control
system maintains the mice in a controlled environment of
constant temperature, pressure, and darkness.
The cages are cylindrical tanks with porous sealed covers and
have an internal height of 1.5 inches and a floor area of 18
square inches. Each cage contains food for the mice. All the
cages receive equal ventilation from a common air supply.
Figure 7-2 shows a cross section of the cages. The inside of
the cage except for the fiberglass tubing is covered with a
layer of porous material.
The environmental control system is illustrated in Figure 7-3.
The environmental control system tank houses a fan to
circulate the air, a charcoal-lithium hydroxide absorption
canister to remove carbon dioxide arid ammonia, a dew-point
control heat exchanger, a moisture separator, and
temperature control heater. The accessories mounted on the
tank include an oxygen supply tank and regulators, the fluid
pump control elements and plumbing for connecting the heat
exchanger to an external cold plate. The entire experiment
package is surrounded by a multilayered blanket of
A biotelemeter with a self-contained power source is
implanted in each mouse to monitor and transmit body
4 to 4V2" long
% to 1/3 oz.
Biotelemetry— the recording and
measuring of certain vital
phenomena of living organisms,
occurring at a distance from the
Figure 7-2 Cross Section of Cage
To mouse -
Mouse ' Cage
Mouse ' ^ Cage
Mouse ^ / Cage a
Mous^ \ ^Cage
J I Li-OH
^ ^ ^
charcoal 2 typs.
Figure 7-3 Environmental Control System
temperature information. The animal activity is determined
from variations in the signal strength as the mouse changes
position with respect to a receiving antenna in the center of
each cage. The data acquisition and processing is done by the
electronics data system.
The experiment is performed during 28 days of the mission.
Before launch, 24 pocket mice are placed in a simulated
flight hardware environment and maintained in a constant
environment for at least three weeks to document the "free
running" circadian periods of body temperatures and activity
of each mouse." Two groups of six mice are selected from the
24 £ind placed into the two flight units following the baseline
run. One of the flight imits is placed into the launch vehicle
while the remaining flight unit is used as a ground control.
The circadian rhythms of each inouse are continuously
monitored' from launch for 28 days minirnum while
continuously maintaining the constant intemal environment
of the flight hard^yare.
Additional groups (those remaining from the 24) of pocket
mice are maintained in a constant environment at the launch
site, and monitored simultaneously with the flight group for
body temperature and activity.
The measurements from this experiment are taken for the
duration of the mission. Data will be transmitted to the
ground data stations every 8 hours. Analyses of the data from
the flight and ground control mice will be reported in a
science report publishecd about a year after the mission.
SKYLAB EXPERIMENT S072
The first formal record of biological rhythms was probably
made by the astronomer, De Mairan, who in 1729 described
diurnally periodic leaf movements in plants held in the dark.
The literature is now replete with evidence of diurnal
periodicity in many forms of life at many levels of
organization. Present day research emphasizes on one hand,
the mechanisms of the so-called "biological clock," and on
the other, the coupling of the clock to environmental stimuli.
Whether control of the period of the clock is predominantly a
physiological oi: environmental phenomenon is debatable on
the basis of existing data. Theoretically, the study of
biorhythms in space would permit resolution of the question
^s to whether terrestrial stimuli indeed set the period or
simply determine its phase.
Periodicity — tendency to recur at
The principal evidence for external stimuli setting the period
of the circadiari rhythm is the (1) remsirkable persistence ahd
precision of the rhythm in organisins kept in constant
environments apparently free of stimuU that are capable of
entraining a self-siistainihg oscillation, and (2) the remarkable
insehsitivity of the free running period to the level of
temperature (temperature compensation). If the control of
the period were truly endogenoiis (metabolic), changes in
temperature should have produced pronounced changes in
period in poikilothermic organisms; On the basis of these
observations^ Dr. Frank Brown of NortHwestem University
has postulated a precise 24-hour component in the circadian
rhythm resulting from entraihment to some "pervasive
Effect of Zero
Most workers, however, believe circadian periodicity to be
primarily inherent in the organism. Recent evidence
implicates a role of genetic structure in setting the period,
loci having been found which can effect an aperiodicity. The
Sky lab experiment is an effort not so. much to provide a
definitive answer to the opposing contentions as to shed light
on the effect bf 2ero gravity and removal from the Earth's
immediate geophysical parameter on a precisely measured
Drosophila eclosion rhythm is the best studied circadian
system of any organism. Techniques fully developed at
Princeton University permit the selection of a piipal
population that would emerge in, e.g., thiree or fouir
successive peaks of activity separated by a precise circadiari
period. Methods of assaying the emergence of the adults in
the weightless state and providing the environmental control
which the experiment requires have been under study at
Northrop Corporate Laboratories.
Drosophila —the fruit fly, used
extensively in experiment
The objective of this experiment is to study the circadian
rhythms of vinegar gnat pupae (genus, drosophila) under
conditions of weightlessness and in the absence of
geophysical variables within a 24-hour period associated with
the Earth's rotation.
The equipment consists of four pupae compartments, the
circadian data system and power supply, and the control
Each cylindrical scaled pupae corhpartment consists
essentially of a control post that supports 180 pupae on a photosensor-a device sensitive
plate, scanning lamps, photosensors, a stimulus Ught, a to light
solution of potassium hydroxide, and environmental
controls. The pupae plate contains 12 beds equally spaced
around its periphery. Each bed contains 16 holes. Pupae are
glued over 15 of the holes so that they completely obscure
the holes; the 16th is uncovered to monitor the scanning
light. One hundred ninety-two photosensors are mounted
under the pupae plate, one for each hole. Twelve of these
photosensors monitor the scanning lights.
Each of the 12 beds has an overhead red scanning light that
transmits through the pupae onto their individual
photosensors. The detection system can discriminate between
an empty pupae case and developing pupae which exhibit
various degrees of transparency during development, but only
after eclosion is sufficient light transmitted through the
empty pupae case to activate the detection system. The beds
are scanned sequentially for 0.5 seconds every 10 minutes.
The sealed compartments are charged with air of specified
composition to maintain the pupae throughout the
experiment. The initial charging pressure is adjusted so that
when the compartments are heated to their experiment level,
the pressure will rise to sea level pressure. The carbon dioxide
concentration and humidity in the compartments are
controlled by a potassium hydroxide solution. The internal
temperature is regulated to automatically supply or remove
A white light provides a stimulus with a wavelength between
400 to 700 nanometers to the pupae to determine the phase
of the biological clock controlling eclosion.
The experiment is performed during the first 20 days of the
mission. All crew operations are to be performed only upon
direction from the ground flight controllers.
In the circadian rhythm-vinegar gnat experiment, a
population of 720 vinegar gnat pupae divided into 4 groups is
placed in Earth orbit in a dormant state. When in orbit, the
pupae are warmed to approximately 20°C to allow
development. Sometime after the temperatures are stabilized,
the pupae are exposed to a single 2-minute pulse of white
light. The light pulse sets the phase of the circadian rhythms
and establishes the baseline from which the circadian
rhythms are determined.
The eclosion of pupae (emerging from puparia) in each of Puparia— pupal cases formed of
the compartments is continuously monitored until the cuticula of preceding larval
experiment termination. instars
In addition to the inflight pupae, an equal population of
pupae will be housed at the laimch site. These pupae will be
stimulated simultaneously with the fli^t group, exposed to
the same controlled environment, and monitored for the
The data acquired from the experiments will be analyzed to
determine any variance among the circadian rhythms
observed in the flight group while in orbit and the circadian
rhythms observed during the baseline run and those observed
in the ground control groups. A significant digression of
either the precision or length of the free-running circadian
periods measured in space from those periods measured on
Earth would constitute evidence of dependency of circadian
organization upon conditions of spacefli^t. Conversely,
continuance in space of the precise free-running circadian
periods measured on the ground would constitute evidence in
favor of the independence of circadian organization of
spaceflight conditions, including weightlessness.
The data from this experiment are recorded from prelaunch
until deactivation of the experiment. Data will be transmitted
to the ground data stations every 8 hours. Results of the
analysis of this data will be published in a science report
possibly early in 1975.
In preceding sections a fundamental tie has been established
between the Skylab experimental program and the science
that guides and disciplines man's quest for knowledge about
himself. In this section, a few classroom activities, discussion
topics and student experiments which the teacher maj^
employ to demonstrate the principles and techniques of
scientific inquiry are suggested. These simple qualitative
classroom activities can be coupled with more precise and
quantitative data and aids from Skylab to enhance the
educational process. The su^ested demonstrations that
represent only a very small sample of those which might be
performed, have been included only to show the scope of
relevant experimental techniques.
Body Mass The evolution of the mammalian skeleton has been
significantly influenced by factors such as gravity, which is
the primary discussion topic of this section.
The weight of an animal is proportional to the gravitational
attraction and. the mass of the body. The relative mass of a
body is directly proportional to its volume. A very large
sphere has much less surface in proportion to its volume
than a very small sphere. If the radius of a sphere is increased,
its surface increases by the square (A = 4nT^ ), but its volume
increases by the cube (V = 4/37rr' ).
The following discussion is adapted from DuBrul*
The operation of the principle that volume of a sphere
increases by the cube may be applied in different ways in the
animal world. Suppose we pretend that the body of an
animal is like a sphere and that four legs support this sphere.
The four legs are subjected to pressure from the weight of the
body. What is the relationship of the thickness of an animal's
legs to volume of its body? A horse has long thin legs. A
moose is lai^er than a horse, but its legs seem to be only a
little thicker. An elephant is still larger, but its legs are
enormously thicker. Now we are near the upper limit of size
for living land animals. Not only is the proportion of legs to
body of these three animals different, but the locomotion is
also different. The horse has a rapid gallop; the moose a
slower pace; the elephant a steady plod.
The African elephant can weigh as much as 6V2 tons. With its
bone structure this elephant is near the limit of its size, while
still retaining its mobility. However, a whale, the largest of all
mammals may weigh forty times as much as an elephant. The
*DuBrul, E. Lloyd: Biomechanics of the Body, BSCS
Pamphlet #5, January, 1963, American Institute of
Biological Sciences, pp 2, 3
whale's bones arie not proportionately thickened, but they
aire strong enough because the whale is supported by water.
Many of the dinosaurs approached whale-Uke size. How were
they £idapted for survival?
A discussion of one of the problems that would arise with the
increase in size of an organism follows.
If an organism were to double in size, could it retain the same
structural makeup under Earth gravity conditions? By
doubling its size, an organism would increase eight times in
volume (weight) with .only an increase of four times in
strength of the skeleton. (The strength of a bone is
proportional to the diameter squared. This scaling restraint is
discussed more fully in Physics, D.C. Heath & Company,
i960 edition, p 45 ff, or in the 1965 edition on page 48 ff.
Reading these pages could lead to an interesting discussion on
evaluation of organisms under varying gravitational
Other interesting problems that could be posed for discussion
• Are animals possessing no skeletons (invertebrates)
subjected to the same limitations as vertebrates?
• How much increase in size or mass would be possible
before additional skeletal strength would be necessary if
an organism were transferred to gravity conditions oh the
Moon (gravity 1/6 Earth's)?
• The leg bones of one animal are twice as strong £is those
of another closely related animal of similar shape. What
would you expect to be the ratios of the animals' heights
The Concept Because of the problems associated with conducting
of Cause experiments involving the use of hormones, the following
Invitations to Inquiry are submitted for discussion topics.
The soiirce of these Invitations is the Biology Teacher's
Handbook (John Wiley, 1970), prepared in cooperation with
the Biological Sciences Curriculum Study. "The teacher
presents the background of the invitations orally and when
necessary at the blackboard.* He then poses the problem of
the invitation arid invites student reaction. Thereafter he
deals with student responses as they arise, asking diagnostic
questions which help students see what is vsrrong with poor
answeirs, reviewing the logic that justifies good responses.
Physics, b.C. Heath & Company, 1965 p 48
*BSCS has developed inquiry slides which relate to there
topics and are related to these invitations.
Sound responses to early problems of an invitation then lead
naturally to the next problem in the invitation and the
procedure of diagnostic and analytical questioning
Subject: Thyroid Action (p i08)
Topic: Unit Causes
'One of the easiest of complications to understand is the fact
that we can always try to break big causes into little ones. A
whole gland, such as the adrensQj for example, can be treated
as a cause. We reinove it and note the consequences of
removal. Then we interpret these consequences as indications
of the. normal effects of the adirenal gland. There is nothing
erroneous about such an experiinent and iriteirpretation, but
it is certainly incomplete, for we can go ori to divide the
gland into parts, such as mediilla and cortex, and redo bur
experiment using one such part at a time. Later, we niay
analyze still further. Perhaps we would, proceed by
distinguishing different kinds of cells in the cortex and trying
to remove one kind of cell at a time— and so on down to
'Back of this progressive analysis of causes into finer knd
finer parts is the idea that somewhiere we will arrive at
irreducible unit causes, or causal elements. However, the
possibility of such elemented causes does not mean that
grosser, composite causes, such as whole oi^ans or tissue
components of organs, are "wrong" or useless. On the
contrary, they may be very useful, not only in iapplied
biology, as in medicine, but also in research.
'Hence, what we want to convey to students is not that one
level of analysis is better or more "scientific" than another,
but only that there are many levels.' (p 108)
Invitation #17 uses this piroceilure to investigate the action of
the thyroid gland.
Subject: Parathyroid Action (p 116)
Topic: Multiple Causation
This Inyitation illustrates that a given effect may be evoked
by what appears to be several different causes.
'This is sometimes referred to as multiple causation, but the
term is something of a misnomer. It si^gests that several
genuinely different things or events can cause precisely the
same effect. This could be the case in nature. However, the
concept of causation underlying much biological research
into causes includes the idea that, ultimately, if several
instances of an effect are identical, the cause will also be
found to be the same.
'It follows from this concept that when we think we have a
case of different causes leading to the same effect, we
proceed to make finer analyses (either spatial or sequential)
in order to find what is common to the apparently different
"Thus, midtiple causation is a complication of enquiry at two
levels. First, it involves the simple possibility that an event
may have "several causes." Second, it involves the more
abstruse notion that several causes may reeilly be one— though,
of course, the common factor, the "true" cause may be
located in several places or react in several different
circumstances, or be involved in several different sequences.
'In this Invitation we deal with "multiple causation" in its
simplest form: the idea of the same causal source lying in
several different locations. We do not introduce the
complication of an underlying common cause acting in
different circumstances or throu^ different sequences.' (p
Subject: Control of Thyroid Secretion (p 128)
Topic: Inhibiting Causes
Invitations 17 and 21 have treated causal factors as being
positive, leading to the appearance or the increase of
something. This Invitation illustrates the fact that a causal
factor may be negative and lead to the inhibition of
Subject: Pituitary— Gonad Mechanisms
Topic: Feedback Mechanisms
'This Invitation has two major points. First, it exemplifies the
fact that experimental tests of hypotheses cannot, as a rule,
verify them. As a rule we can demonstrate only that the
hypothesis is not possible or that it might be the case. Only
when all the possible alternative hypotheses are known can
experimental test, by eliminating all but one alternative,
verify that one. This situation is sometimes referred to as
"the falsif lability, but not the verifiability of hypotheses."
The point is that we are rarely in a position to say with
certainty that we know all the possible alternatives.
"The second function of the Invitation is to add a last item to
our understanding of cause-effect enquiry: the existence of
complex 'interactions of causes,
"The Invitation is based on a real case— the sexual cycle in the
mammalian female. However, it refers to oi^ans and materials
only by code letters, A, B, C, and so on. This is done for two
reasons. First, it makes it possible to use the Invitation at any
time, since background information is not required. Second,
it permits us to put our emphasis on the general pattern of
interaction, rather than on the specific case.' (p 130)
The previous. Invitations are examples of how students can
• function of various glands,
• relationship among gland organs and the hormones
• feedback mechanism as a regulator of hormone secretion.
They stress the role of critical observation and involve
students in designing experiments, interpreting data,
formulating hypotheses, identifying problems, and
performing other tasks related to the investigative nature of
Students may determine the relative caloric content of food
by using a standard calorimeter or the homemade one shown
in the sketch.
(Do not leave in tube
Test tube (bottom
should be approximately
2 cm above food.
Soft drink can -
Diagram from BSCS Patterns and Processes 1966 p. 78
Cover cork with
When using a homemade calorimeter, satisfactory results can
be obtained by following these procedures:
1) Measure 2/10 gram of food to bie tested and place on the
2J Place 10 ml of water in the test tube and record the
temperatiire of the the water;
3) After the initial reading, remove the thermometer from
the test tube; .
4) Ignite the food and place calorimeter over burning food
with flame directly- under the test tube. Bum food to an
ash. If flame goes out, repeat steps 1, 2, 3, and 4.
5) Immediately measure the resulting increase of water
Note: If water should boU, the amount of water should
be increased in multiples of ten ; or decrease the amount
of' food. If the water boils, most of the heat energy is
being used as heat of vaporization of the water (540
CEllories per gram);
6) The caloric content: of the food is calculated as follows:
change in teinperature (Celsius) x number of ml of water
= calories present in the amount of food burned.
Note: This procedure .provides a caloric content in small
calories . (c). (c is the heat necessary to raise the
temperature . of I'.mJ of water 1°C.) Theire is a larger
unit, the kilocalorie or calorie with a capital G, which is
1000 times as big as the small c calories and is the unit
commonly used today in specifying caloric content of
Foods that provide particularly good results include nuts,
cereals, sugar, and dried bread.
Students working in paii:s can gather data on heart rate and
breathing rate Using amount of activity as a variable. One
student can record the pulse rate and breathing rate of
another student lying at rest, standing, after mild activity,
and after more strenuous activity. The data gathered can be
tabulated in the following form.
Class results can be graphed on 6ach activity to illustrate
individual differences within the class. Average results for all
activities can be graphed to illustrate the effects of the
amount of activity on these two body functions.
The heart of a double pithed frog can be attached to a
kymograph for observation of amplitude and rate of heart
beat. (For pithing instructions, see Follansbee Harper Animal
Behavior, BSCS Laboratory Block, D. C. Heath & Company,
Kymograph— an instrument for
recording variations or undula-
tions, arterial or other
The heart can be cooled using iced Ringer's solution (a
solution of salts comparable in composition to the frog's
body fluid) to slow it down and a chemical, such as adrenalin
(1 in 10,000), to speed up heart action.
Physical stimulation, i.e., poking with a pin or small electrical
stimulation, will also alter the rate.
Lung Capacity To study the relative lung capacities, the setup shown in the
sketch can be used. Have students, using a normal breath,
blow into the rubber tubing and measure the amount of
After refilling the jar a second student may i:epeat the
experiment. For comparative purposes students rhay wish to
repeat the experiment after filling lungs to capacity and
exhaling all the air in the lungs to displace the water.
For more accurate volume measurements, mark the water
level with a grease pencil, remove the jar, empty it
completely, and with jar in upright position measure the
amount of water necessary to fill the jar to the pencil mark.
This experiment demonstrates the amount of CO2 produced
under different levels of physical activity.
Measure 100 ml of water and test for CO2 by adding 5 drops
of a 1% solution of phenolphthalein. If a pink color appears
in the water and rernains for at least fifteen seconds, it can be
assumed there is no acid in the water. If the water remains
clear, there is acid present and it must be neutralized before
the amount of CO2 added can be deterrhined. To neutralize
the water add dilute sodium hydroxide (NaOH) solution drop
by drop until the water turns slightly pink. Be sure to count
and record the number of drops requiired. Save the sample of
water and use it as a control reference.
1) Have a student lie on his back inhaling through the nose
and exhaling through a tube which is inserted in a flask
with 100 ml of water containing 5 drops of
phenolphthalein for one minute.
2) Add sodium hydroxide (NaOH) drop by drop as before
until the pink color appears as in the control solution.
The difference in the number of drops of NaOH required
to color the control solution and experimental solution is
an indication of the amount of CO2 added.
3) For comparison pvirposes, the experiment can be
repeated after exercising vigorously for one minute, e.g.,
deep hand bends, running in place, etc.
4) Additional activity: have the student undergo some
physical activity such as running up a flight of stairs. (The
work required to run up the stairs can be calculated if so
desired.) Then have the student breathe into the
phenolphthalein solution for the same length of time as
before. Note the number of drops of NaOH added to
indicate a change.
If phenolphthalein is not available, the same relative meas-
sures may be obtained by blowing into limewater and com-
paring the amount of precipitate formed when CO2 reacts
with the calcium hydroxide to form calcium carbonate.
Students may want to investigate some of the visual illusions
that are discussed in most hi^ school psychology textbooks.
Other sense investigations can also be used, i.e., have students
make a 1-inch grid of washable ink on the palm of the hand,
back of the hand, and on the forearm. The grid should be
made up of 1/8-inch squares. By using 3 inch nails, some of
which have been placed in ice water and some in hot water,
the students can attempt to map the heat and cold receptors
in the grids. Note: one student should place the nails for
another student who is blindfolded. Students must take care
not to push too hard on the nails or the pain or pressure
receptors will be stimulated, confusing the experimental
By compjiring the location and number of receptors in the
three grids, students can get an indication of the more
sensitive areas to heat and cold.
Vestibular The student may perform experiments that provide a
Apparatus measure of the role and function of the vestibular apparatus
in maintaining balance and posture. In order to stress this
body system, the student can be seated in a swivel chair and
spun "X" number of times. The effect of this stress can be
qualitatively observed by assignment of selected tasks such as
walking a straight line, picking up small objects, tossing coins
into a small bucket, etc.
English sparrows may be captured during the winter months
when the photoperiod is approximately nine hours. The birds
must be sacrificed in order that the gonads may be examined.
(A painless way to kill the birds is to dip their beaks into the
fimiesof carbon tetrachloride. Hold the birds beak into the
opening of a bottle of CCL4 . Students should avoid breathing
Measure the weight and size of the gonads of a male and
female. This serves as a control.
The remaining birds are to be placed in covered cages with a
light and timing device to increase the photoperiod to 13 or
14 hours. Birds should be exposed to the lengthened
photoperiod for three weeks. One pair should be kept under
the 9-hour photoperiod to serve as additional control.
At the end of the three-week period, the size of the gonads of
the control and experimental birds may be examined.
Circadian Circadian periods such as photoperiodicity can be
Rhythms investigated in the laboratory or classroom. Mice can be
placed in a cage with an activity wheel. A 24-hour recording
device attached to the wheel can be used to record the
number of revolutions and time of day. By using timers to
control artificial lighting, the photoperiod can be set to cover
a wide range of light-dark cycles. Analysis of activity
patterns, light-dark cycles, food consumption, and body
weight wUl reveal the influence of photoperiod.
Glossary of Terms
GLOSSARY OF TERMS
Aberration Any deviation from the normal number.
Biastoid Pertaining to embryonic cell forms
Biorhythm A biologically inherent cyclic variation or recurrence of an event or state,
such as the sleep cycle, circadian rhythms.
Cation An ion carrying a charge of positive electricity; therefore going to the
negatively charged cathode.
Chromosomal Pertaining to the body in the cell nucleus that is the bearer of genes.
Circadian Relating to biologic variations or rhythms with a cycle of about 24 hours.
Colchicine An alkaloid obtained from colchicum.
Cytogenetics Study of heredity— cytology and genetics.
Diastolic Relating to the dilation of the heart cavities, during which they fill with
Diuresis Increased discharge of urine.
Diurnal Pertaining to day or daylight.
Endocrine The internal secretion of a gland.
Endogenous Originating or produced within the organism or one of its parts.
Epinephrine The chief hormone of the normal adrensil medulla, adrenaline.
Erythropoiesis The formation of red blood cells.
Exogenous Originating or produced outside.
Friability Easily crumbled or reduced to powder.
Globulin A simple protein found in blood, milk, muscle and seeds.
Hematopoietic Blood forming.
Hemolysis The alteration or destruction of red blood cells in such a manner that
hemoglobin is liberated into the medium in which the cells are suspended.
Hemostatic Arresting the flow of blood within the vessels.
Histochemical Chemistry of the tissues.
Homeostatic The state of equilibrium in the living body with respect to various
functions and to the chemical composition of fluids and tissues.
Homeothermic Denoting the warm blooded animals.
Humoral Relating to the extracellular fluids of the body.
Hyperbaric Pertaining to pressure of ambient gases greater than 1 atmosphere.
Hypobaric Characterized by low atmospheric pressure.
Hypodynamia Diminished power.
Hypotension Subnormal arterial blood pressure.
Leukocyte Any one of the white blood cells.
Lysis Destruction, as of cells by a specific substance (lysin).
Mesenchymal A pluripotential cell form found between the ectoderm and entoderm of
young embryos. These cells give rise to any of the connective or
Microflora Microscopic forms of bacterial life.
Mitosis The usual process of cell reproduction consisting of a sequence of
modifications of the nucleus that result in the formation of two daughter
cells with exactly the same chromosome and deoxyribonucleic acid
(DNA) content as that of the original cell.
Morphologic Relating to the science which treats of the configuration or the structure
of animals and plants.
Myocardium Heart muscle.
Neutrophil A mature white blood cell in the granulocytic series.
Oculogyria The limits of rotation of the eyeballs.
Orthostatic Relating to or caused by the erect posture.
Organelle One of the specialized part of a protozoan or tissue cell serving for the
performance of some individual function.
Osteoblastic Relating to a bone forming cell.
Osteoclastic Relating to the activity in the absorption and removal of osseous (bony)
Otolith Part of the vestibular apparatus (ear stone).
Parenchymal The distinguishing tissue of a gland.
Phagocytosis Engulfing of microorganisms, other cells, and foreign particles by
PoikUotherinic Denoting the so-called cold blooded animals and the plants.
Reticulocyte A young red blood cell.
Spatial Relating to space, or a space.
Steroid Hormone of the adrenal cortex.
Stressor Any force which stresses the body, organ, or system.
Systolic Relating to the rhythmical contraction of the heart.
Venous Relating to a vein or to the veins.
« U. S. GOVERNMEKT PRINTING OFFICE : 1973 729-S16/9U8