Transcript File

Space Medicine
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What is Space
Medicine?
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The study of how
different body systems
work in a zero gravity
environment.
What kind of counter
measures help maintain
normal body function.
Body System Changes
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Almost every system of the human body is
affected when the human body enters zero
gravity.
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GI Function (your bowels)
Liver Function (how your body processes waste)
Fluid and Electrolyte imbalances
Circulatory dynamics (the heart)
Organ blood flow
Hormonal and metabolic (how you burn energy)
Muscles and bones
Effects on the Cardiovascular
System
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There is a fluid shift in microgravity
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Facial Edema, cranial veins dilate, heart enlargement
Blood no longer pulled to extremeties, which induces rapid loss
of water
Upon return to Earth the body rapidly returns to normal fluid
shifts which can cause orthostatic hypotentsion and syncope.
Counter Measure for
Cardiovascular Shifts
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LBNP (Lower Body Negative Pressure Device) device as substitute
for Earth’ gravity. Protocols may vary based on time spent in space.
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Creates an equivalent physiologic stress by creating suction on the lower body
Ingestion of Isotonic Saline just before re-entry also helps to counter
orthostatic intolerance and Cardiovascular Deconditioning.
Use of G-suits upon re-entry to help with orthostatic intolerance.
Operational Tilt Test
.
Operational Tilt Testing
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Operational Tilt Test is Preflight and Post-flight test to
determine the crewmembers
orthostatic intolerance.
Upon return to Earth sometimes
the crew will have a hard time
maintaining blood pressure
above their heart which leads to
decreased blood flow to the
brain which can result in
fainting.
During the test the crew’s ECG
and blood pressure, and
ultrasound echo are constantly
monitored
Effects on Bone
Once Gravitational Stress is removed the
bone calcium and phosphorus are
excessively excreted.
 3.2 % of average bone loss occurs after
nearly 10 days of weightlessness.
 Can lead to bone fractures
 Therefore Countermeasures extremely
necessary
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Countermeasure to Reduce
Bone Loss
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Weight bearing exercise can
reduce bone loss. (Advanced
Resistive Exercise Device –
ARED)
Treadmill and Ergometer
and use of LBNP
combination (this
combination helps to
prevent loss of coordination
between the nervous system
and the muscles which affect
balance and motion.)
Regimen is for 2 hours of
exercise per day.
Nutritional Supplements
also being evaluated.
Mike
Foal
Sunita Williams
Completes the
Boston Marathon
in Space
Effects on Muscle
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Rapid Atrophy due to lack of use in the
microgravity environment.
Muscle fibers have two categories: Slow-twitch
muscle fibers, and fast-twitch muscle fibers.
In microgravity there is rapid degradation of
muscle fibers from slow twitch to fast twitch
Slow twitch are more efficient at using oxygen to
generate more ATP for continuous muscle
contractions and don’t fatigue as fast.
Fast twitch use anaerobic metabolism which
makes them better at short bursts of strength or
speed and fatigue fast.
Countermeasure for Muscle
Degradation
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Includes an exercise protocol
that induces maximum muscle
power for a long distance. (ie
Treadmill running, bike training
(ergometer)
New research into Pulsed
Electromagnetic Fields on the
tissue at a cellular level to
induce use of both muscle
fibers. May also prove useful
in keeping bone loss at bay.
http://research.jsc.nasa.gov/P
DF/SLiSci-12.pdf
Space Motion Sickness
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Space Motion Sickness usually occurs a few
minutes or a few hours after entering
weightlessness.
Characterized by headaches, malaise, nausea
and vomiting
60-70% of all astronauts experience this.
Usually occurs first few days and then
disappears
This occurs due to vestibular, inner ear, visual,
skin and joint/muscle receptors by the exposure
to microgravity.
Countermeasure for Space Motion
Sickness
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Biofeedback training
Adaptation training using virtual reality
 Water immersion training
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Medications are used upon symptoms of
the Space Motion Sickness (ie.
Promethazine hydrochloride)
Hematologic and Immunologic
System
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In Microgravity there is a change in the shape of
the red blood cells (Spherical vs Discoid Shape)
ADD PICTURE
Anemia is characterized after 4 days into space
flight. (decrease in the number of red blood
cells)
After 3 months in space there is a 15% decrease
in red blood cell volume.
They will return to normal upon return to Earth’s
Gravitational Forces
Activity of lymphocytes reduces but has rarely
caused practical problems
Effects of Space Radiation
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Astronauts are subject to more Radiation
than they would be exposed to on Earth.
Galactic cosmic radiation
 Solar Particle radiation (from the sun)
 Geomagnetically trapped radiation
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Crew must monitor their radiation level
with personal dosimeters
 Could have potential effects of infertility,
cancer and other diseases
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Interesting Facts
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During the Apollo program, there were several nearmisses between the astronauts walking on the surface of
the Moon and a deadly solar storm event. The Apollo 12
astronauts walked on the Moon only a few short weeks
after a major solar proton flare would have bathed the
astronauts in a 100 rem blast of radiation. Another major
flare that occurred half way between the Apollo 16 and
Apollo 17 moonwalks would have had a much more
deadly outcome had it arrived while astronauts were
outside their spacecraft playing golf. Within a few
minutes, the astronauts would have been killed on the
spot with an incredible 7000 rem blast of radiation. The
daily dosage of radiation on the Space Station is about
equal to 8 chest X-rays per day.
Are We Ready for Mars?
There are still many things that we need to
understand about the human body’s
response to a microgravity environment.
 NASA in collaboration with the NIH and
other Research universities are constantly
conducting studies to determine more
effective countermeasures to combat
these effects.
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Using The Zero G Airplane for
Testing Countermeasures
Zero G
Airplane
Environment
 Why
test
experiments in
Zero G plane?
 18-24 sec
Weightlessnes
s per parabola
 30-40
parabolas per
flight
Properties of Water in Zero G
o
individual H2O molecule is electrically
polarized,
o
meaning the end with the two
hydrogen atoms has a small positive
electric charge, while the end with the
oxygen atom has a small negative
charge.
o
A loose electrical connection called
"hydrogen bonds" form between
neighboring molecules: The positive
end of one molecule hooks up with the
negative end of its neighbor, and with
enough of these hydrogen bonds in
place throughout the bubble, the water
clings to itself, surface tension
o
On Earth, gravity overrides the effects
of hydrogen bonds, making a bubble
of water splat on the ground.
The END
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