we are t minus 30 seconds initiate
systems check
musculoskeletal system
musculoskeletal system is go
neural vestibular system
neural vestibular system go
cardiopulmonary system
cardiopulmonary system go
cardiovascular system
cardiovascular system go
all systems are go we are t minus 10
9
eight
seven
six
five
four
three
two
one
we have liftoff we have liftoff
liftoff of the space shuttle and it has
cleared the town
hi welcome aboard the space shuttle
columbia and space lab life sciences 1.
after 10 years of flying space shuttle
missions we're becoming accustomed to
the strange things that can happen in
space but it hasn't always been that way
when we first went into space no one
knew how the human body would react to
space flight
we wondered if we could survive in
weightlessness
and we wondered if we could work in
space okay i'm out
okay
thirty years later we know that the
answer to both of these questions is yes
but in spite of our successes in space
many questions about the effects of
space flight on the human body remain
unanswered
during the flight of space lab life
sciences 1 my colleagues and i will try
to answer some of these questions
the human body is much like the shuttle
it is a very complex sophisticated piece
of living machinery that relies on
several subsystems to perform its
mission
where the shuttle has a propulsion
system a life support system a guidance
system and so on our bodies have systems
like the cardiovascular system
the cardiopulmonary system
the renal endocrine system
the blood and immune systems
the musculoskeletal system
and the neurovestibular system
the shuttle systems communicate with
each other to keep the spacecraft flying
smoothly
in a similar way our body systems also
talk to each other to maintain what is
called homeostasis
or a stable internal environment
all of our body systems are affected to
some degree by space flight
the most dramatic change occurs
immediately after we become weightless
on earth the pull of gravity normally
pulls our body fluids in our feet legs
and abdomen
but when we enter space and become
weightless the fluid in our bodies is no
longer pulled down toward our feet
instead it shifts up to our chest and
head
since 80 percent of our body is fluid
that changes the way we look
our faces get puffy
and our legs get skinny
we call this the bird legs of space
after we're up here for a while we adapt
somewhat to the fluid shift
but our bodies remain in this altered
state until we're back on earth
the weightlessness affects our bodies in
another way too it's called space motion
sickness it's much like being seasick on
earth
but luckily our bodies adapt to this new
environment and so it isn't really a
problem after the first couple of days
the fluid shift and space motion
sickness are easily recognizable changes
that take place in weightlessness but
less obvious changes also occur
right down to individual cells
during the flight of sts-40 space lab
life sciences 1 my fellow crew members
and i will introduce you to the six
major body systems
we'll learn how they function on earth
and how space flight may affect them
our cardiovascular system is a network
of over 96 000 kilometers of blood
vessels enough to go more than twice
around the earth
these blood vessels include arteries
which carry freshly oxygenated blood to
all the tissues in our bodies and other
vessels called veins which bring back
waste-laden blood so the process can be
repeated
the driving force of the cardiovascular
system is the heart
it's a pump that forces blood through
the arteries and the veins
our heart pumps or beats about 60 times
a minute every minute of our lives
if you live to be 70 years old your
heart will pump more than 2 billion
times
our cardiovascular system works well in
gravity
whether we're lying or standing we
always have an adequate supply of blood
for vital organs like the brain
but when we go into space and take our
hearts out of their normal environment
some strange things happen
the upward shift of fluid in our bodies
tricks the heart and its sensors into
believing that there's an increased
blood supply
so our heart tries to compensate
first the muscle structure of our heart
stretches so that it can hold more blood
when this happens other body systems
tell our kidneys to eliminate what
appears to be excess fluid
as the fluid level is reduced we believe
our bone marrow shuts down its
production of red blood cells in order
to keep our blood from getting too thick
pretty soon the amount of blood in the
red cells in our body is less than we
have on earth
with less blood to pump our heart
shrinks
back to about the same size it is on
earth
but when we return to earth from space
gravity again pulls much of our blood
back to our legs
now there's not enough blood to go
around and some of us will get
light-headed and dizzy for a short time
until our bodies get more fluids and
manufacture more blood
spite of this there's no indication that
space flight causes any permanent
problems for our cardiovascular system
but during this flight we're going to
investigate this matter more closely
before we departed earth i had a long
plastic tube inserted into a vein in my
arm
this tube is called a catheter
the tube was advanced in a vein to a
point just above my heart
during the first few hours of flight
when the fluid shifts occur we're able
to measure the central venous pressure
near my heart
central venous pressure is directly
related to the volume of blood our heart
pumps
once we get back to earth we'll do the
same experiment see if the central
venous pressure measurements differ
if our suspicions are correct we'll
demonstrate that the fluid shift caused
by weightlessness increases activity and
changes the control mechanisms of the
heart and circulation
information like this will help us to
better understand the changes we go when
we first enter weightlessness and it
will give us insight into the possible
effects of long-term weightlessness
as well as diseases of earthbound
patients
the cardiovascular system works closely
with another body system called the
cardiopulmonary system
cardio refers to the heart and pulmonary
refers to the lungs
this lung heart connection is right in
the middle of the cardiovascular system
but not literally here's what i mean
the heart pumps blood through our
arteries and veins the blood in turn has
an equally important job
when the blood is on its way to our
tissue and organs it is said to be
oxygenated meaning that it is carrying
oxygen to all of the cells in our bodies
when blood is returning from the cells
it is oxygen depleted
meaning that the oxygen has been used up
and in its place is carbon dioxide
looking at a diagram of the
cardiovascular system we see that it's a
closed system
if this is true then how does the blood
get a fresh supply of oxygen to carry
back to the cells
that's where the lungs come in
oxygen depleted blood is pumped from the
heart to the lungs
think of the lungs as two large airbags
filled with thousands of tiny blood
vessels called capillaries
my friend here is going to help me show
what happens when we take a breath of
air
when we breathe
air rich with oxygen enters the lungs
now we've got two lungs full of fresh
air and oxygen
and we have a network of small blood
vessels filled with oxygen depleted
blood
now something quite fascinating happens
the oxygen in the lungs and the carbon
dioxide in the blood are going to trade
places through the thin membranes that
line the lungs this phenomenon is called
gas exchange
now the air in the lungs is optionally
depleted and the blood is oxygenating
okay now you can breathe
thank you
the blood then returns to the heart
where it's pumped out to the body to
nourish the cells and give them oxygen
it then returns back to the to the heart
and then again in the lungs where the
processes again repeated
on earth where gravity tends to pull
blood toward our feet the majority of
the blood in the lung stays near the
bottom and the air stays mostly in the
top
but in space where the fluid in our body
shifts upwards it is felt that there
will be a more even distribution of
blood and air in the lungs
that means that the lungs should
function even more efficiently in space
than they do on earth
spacelab's gas analyzer is going to help
us determine if this is true
by breathing into the rebreather device
we'll inhale a mixture of traceable
gases
when we exhale the mixture the gas
analyzer will identify each gas and
determine the quantity that was absorbed
by the bloodstream
investigators back on earth will then be
able to determine if gas exchange in the
lungs is actually more efficient in
space
if that is the case it may help us to
better understand certain respiratory
problems that people have back on earth
if you're a healthy young person
weighing about 120 pounds over 60
percent or 72 pounds of your body is
made out of water
that means that water is the most
abundant and the most important fluid in
your body
but how do we keep our body water at a
constant level
every time we perspire go to the
bathroom
we rid our bodies of water and every
time we take a drink of water
we add water back
so how does the body keep the water in
balance
this is done for us automatically by our
renal endocrine system
renal refers to the kidneys
and the endocrine system is a collection
of hormone-secreting glands
that include
the hypothalamus
the pituitary
the thyroid gland
the pancreas
and the adrenal glands
the primary body compounds regulated by
this system are water and electrolytes
when we drink water or other fluids they
go into our gastrointestinal tract
from there water and electrolytes are
absorbed into the bloodstream by a
process called osmosis
the cells in our bodies then absorb
whatever water they need from the
bloodstream
the cells also dump water along cellular
waste into the bloodstream
as the blood passes through our
endocrine system
it is monitored for different metabolic
products
two of the endocrine glands the
hypothalamus and the pituitary monitor
fluid levels in the blood
too high too high
if the fluid level is not right they
will release a hormone
and that hormone tells the brain there's
a problem
if the fluid level is too low
the brain tells us that we're thirsty
but if the fluid level is high
the brain tells the kidneys to eliminate
fluid
through an elaborate filtering process
our kidneys remove the excess fluids and
waste from our blood and store it in our
bladder in the form of urine
when our kidneys are told by our body to
get rid of water
we make more urine in the body
our bladders fill and we get the urge to
urinate
but what does all this mean for the
space traveler
for one it means that when we enter
weightlessness the body fluids shift
upward
and our renal endocrine system will tell
our bodies to eliminate fluid
what we don't know is how weightlessness
affects the production of hormones that
keep our fluid levels balanced here on
sls 1 we're investigating all the
changes that occur during space flight
changes in the hormone production
changes in how the kidney functions
and the circulation
and with this new knowledge we hope to
shed new light
on things like
how and why we deconditioned during
space flight
and on earth problems like orthostatic
hypertension and heart failure
all of us know that blood is essential
for life
but do we really know why
blood has two very important jobs first
it transports oxygen and carbon dioxide
to and from the millions of cells in our
bodies
blood is also a defense mechanism that
allows our bodies to fight infection and
disease
blood has three components
red blood cells which do the
transporting of oxygen and carbon
dioxide
white blood cells which fight infections
and a watery fluid called plasma which
makes our blood liquid and allows it to
flow through the blood vessels
let's take a look at each of these
components a little closer
red blood cells could be compared to
millions of taxicabs zooming around in
our bodies
as each red blood cell taxi passes
through our lungs it's flagged down by
an oxygen molecule
the oxygen is wanting to go to one of
the millions of cells that makes up our
bodies
so the red blood cell takes off through
the cardiovascular system toward that
destination
once there the oxygen gets out and goes
to the cell
now like any good taxi driver the red
blood cell doesn't want to make a return
trip without a paying customer
so while at the cell he picks up a
carbon dioxide passenger for the return
trip to the lungs
without red blood cells our cells can't
get the oxygen they need to sustain life
white blood cells also perform an
important function they are a major part
of our immune system
from time to time foreign substances
enter our bodies
these substances might be bacteria
viruses or even something like a
splinter
we might compare the white blood cells
to a good watchdog in our yard
when someone or something harmful comes
into our yard our watchdog
the white blood cells work the same way
except there are millions of them
when a foreign substance enters our
bodies the white blood cells attack and
repel the intruder
there are several types of white blood
cells but the ones that we're interested
in on this flight are called lymphocytes
the red and white blood cells would have
a difficult time making it through our
blood vessels if it weren't for a liquid
called plasma
in the red fluid we call blood
cells make up about 40 to 45
the rest is plasma
since plasma is a fluid it is really
affected by the upward fluid shift that
takes place in our bodies when we first
encounter weightlessness and that
affects our body's overall blood supply
here's how
when the fluid in our bodies drifts
upward
sensors in the circulatory system and
the endocrine system send a message to
the brain saying that there's too much
fluid
the brain then tells the kidneys to
reduce the fluid volume
this is probably accomplished mainly
through urination
once the fluid level has been reduced
blood cells make up more than 45 of the
blood supply
in other words our blood becomes thicker
to compensate for this
we think the bone marrow decreases its
production of red blood cells until the
ratio returns to about 45 percent so
once again our bodies adapt to the
changes of space flight
but when we return to earth we face
another problem
we find that we've lost both blood
volume and red blood cells
the loss of blood volume is a problem
immediately upon returning to earth
because earth gravity is again pooling
blood in our legs the decreased volume
makes it more difficult for blood to be
pumped to our
brain this can lead to lightheadedness
and a woozy feeling right after landing
we begin working to correct this problem
even before we land by drinking lots of
water
by drinking water we begin to replace
the plasma in our blood
but once the plasma level is increased
we face another problem
now we have fewer red blood cells than
we should have this condition is called
space anemia even though it doesn't
actually happen until we're back on
earth
face anemia will continue until the body
manufactures enough red blood cells to
bring the plasma cell ratio back to
about 45 percent
during the sls-1 mission we're studying
several ways in which space flight may
affect the blood and immune system
for example in the past we have found
that astronauts have fewer lymphocytes
after flying in space
and the lymphocytes they did have were
not as effective in fighting infection
as they had been prior to space flight
at various times throughout this mission
we're going to draw blood from the crew
these specimens will be studied later on
earth to determine if the lymphocytes
ability to respond to infection
decreases the longer they remain
weightless
this is an important question to be
answered
without a functioning immune system our
bodies would become easy prey for
disease
most structures are designed with a
specific purpose in mind
the orbiter was designed to function in
the unique conditions of space
our bodies were designed to function on
earth where there's gravity
in fact our body's musculoskeletal
system needs gravity to function
properly
of all the body systems we're studying
during sls-1 the musculoskeletal system
may be the only one that has serious
problems adapting to the changes it
encounters during space flight
by pulling against our bodies gravity
makes our bones and muscles work and
become stronger
each time we take a step and push our
weight forward we perform a weight
lifting exercise for the muscles in our
legs
activities like climbing stairs make our
muscles work even harder
but in space nothing has weight so our
muscles don't have to work the same as
they do on earth when muscles don't work
in their usual way they become weaker
most of us have known someone who's
broken an arm or leg and had to wear a
cast while the bone healed
while in the cast the muscles of that
arm or leg didn't have to work
and once the cast was removed the muscle
was weak and had lost its bulk
the same is true for people who've been
confined to a bed for a long time and
could not use their muscles
in space we work our muscles on
treadmills and exercise bikes but the
results still aren't the same as they
are on earth
imagine that every day we lift the
barbell that weighs 100 pounds
then one day we go on a trip it lasts a
month and we only have a 40 pound
barbell to take with it
even though we lift the 40-pound barbell
every day
the 100-pound barbell is going to be
hard to lift when we return from our
trip
the same is true about space flight
even though we exercise in space we're
going to be weaker when we return
depending on how long we've been in
space it may take us weeks or even
months to regain the strength in our
muscles that we've lost
it could be even worse for astronauts
who will someday live on the space
station or at lunar bases
not to mention a trip to mars it could
last a year or more
mussels aren't the only parts of our
bodies that suffer during space flight
weightlessness also causes our bones to
lose the minerals calcium and phosphorus
many of us don't think of our bones as
being alive but they are really very
active
in our bone are two types of cells
osteoclasts which get rid of old bone
matter
and osteoblasts which build new bone
because of the activity of these two
types of cells our bones are in a
constant state of tearing down and
rebuilding
the balance of these cells seems to be
tipped slightly in favor of the
osteoblast cells that's why our bones
grow stronger
but what happens in space is still
somewhat of a mystery
since there is no weight to bear in
space then there is no stress on our
bones as they go through the rebuilding
process
this seems to affect the structural
integrity of our bones
bone density recovers but without stress
they may not grow as strong
the only way to prove this theory is to
test some of our bones for strength
and the only way to do that is to remove
the bone
and so far we've had no volunteers
so nasa is working on ways to study bone
strength without removing the bone
finding a way to test bone strength is
going to help us to treat elderly
patients who have a common bone problem
known as osteoporosis
here on sls 1 we're going to measure the
level of calcium producing hormones and
compare them directly to the uptake and
release of calcium in the body
it will be the first time that this has
been done in the weightlessness of space
it's a spectacular view out the window
but most of the time looking outside
doesn't tell us if we're flying the way
we should
since there aren't a lot of visual
references in space
the shuttle has a guidance system that
helps keep us in the proper position
we have a guidance system in our bodies
too
it's called the neurovestibular system
and it's what keeps our bodies in the
proper orientation on earth
the neurovestibular system is very
sensitive to gravity
in fact it's gravity that makes it work
deep inside our inner ear
in the vestibular organ
are thousands of tiny hairs
resting on top of these hairs are
microscopic clumps of crystals called
otoliths
on earth gravity pulls the otoliths in
different directions according to the
type of activity we're doing
this in turn bends the tiny hairs
sending messages that tell the brain
before hanging upside down
accelerating
or any other sensation that has to do
with body movement
the neural vestibular system also uses
sensors in our muscles to determine
sensations of motion or changes in
position
but most of all it relies on our eyes
we might even say that the neural
vestibular system's main purpose is to
create a stable platform for our eyes
when our eyes can't lock onto what we're
looking at
we can get a queasy feeling we call
motion sickness
it's the same feeling some people get
when they ride a wild ride at an
amusement park
everything rushes by in a blur
and before long they think they might
get a second look at the hot dog they
just ate
some of us who fly in space get a
similar feeling we call it space motion
sickness
that doesn't mean riding the shuttle is
like climbing aboard a tilt-a-wheel at a
carnival
but it does mean that space flight can
confuse our neurovestibular system and
disorient the visual references we rely
on for stability
there's a reason for this
when we get into space gravity no longer
pulls down on us the way we're used to
on earth
things start to float away and for all
practical purposes
objects become weightless
in this environment the vestibular
system functions differently than it
does on earth and we no longer have a
way to tell our brain what the right
body position is
without the vestibular system
functioning the way we're used to
some of us get confusing signals in our
brain
our eyes tell us that our feet are off
the ground
but our vestibular organ doesn't give us
the sensation of falling that we expect
usually after a few days in flight our
bodies adjust to the weightlessness and
the space motion sickness goes away
not everyone experiences space motion
sickness
and that's one of the medical mysteries
we'd like to know more about
the reason is quite obvious
imagine getting off a ride at a carnival
and someone hands you an algebra book
and tells you to work a few problems
that's what it's like for an astronaut
who's suffering from space motion
sickness
it's rather difficult to concentrate on
an experiment if all you can think about
is how sick you feel
we want to have as much productive time
as possible when we're in space
so to help us learn more about the
effects of space motion sickness and how
to treat it we're going to do some
experiments here on sls1
one of my favorite experiments involves
this rotating dome
what the dome does is to help us see how
visual cues affect the way our body
responds to do the experiment millie
will put her head in the dome
and look at the dots as they rotate
her eyes naturally want to lock onto the
dots
this causes her body to want to keep up
with her eyes and pretty soon her whole
body will feel like it is turning
but it really isn't
a camera mounted in the dome is
recording her eye reaction
back on earth scientists will study this
and other data we've collected to see if
they can answer some of the questions
about how our neuro vestibular system
works and why we get space motion
sickness
i'll leave you with a small bit of
advice
the next time you're on a roller coaster
ride and you feel yourself getting sick
just close your eyes
our body systems are so different from
each other yet they all depend so much
on each other
they perform their jobs each day in a
way that most of us never realize
our goal at nasa is to enable the human
exploration of space but to do that we
have to understand how space affects our
bodies
space lab missions like this one are a
step toward that goal but only a small
step
orbiting laboratories will allow us even
longer periods to investigate the
mysteries of the human body
hopefully the benefits of all
space-based research may someday help
solve the puzzles of such earthbound
problems as heart disease emphysema
osteoporosis and other disorders
the possibilities are as limitless as
the stars themselves
spacecraft life sciences one has been a
valuable learning experience for all of
us we're really glad you could join us
on this voyage of medical discovery
do
you