Space Medicine What is Space Medicine? 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
Almost every system of the human body is affected when the human body enters zero gravity. 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 There is a fluid shift in microgravity 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 LBNP (Lower Body Negative Pressure Device) device as substitute for Earth gravity. Protocols may vary based on time spent in space. 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 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 crews 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 Countermeasure to Reduce Bone Loss 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 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 dont 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 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 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 Biofeedback training
Adaptation training using virtual reality Water immersion training Medications are used upon symptoms of the Space Motion Sickness (ie. Promethazine hydrochloride) Hematologic and Immunologic System 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 Earths Gravitational Forces Activity of lymphocytes reduces but has rarely caused practical problems Effects of Space Radiation 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 Crew must monitor their radiation level with personal dosimeters Could have potential effects of infertility, cancer and other diseases Interesting Facts 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 bodys 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. Using The Zero G Airplane for Testing Countermeasures Zero G Airplane Environment Why
test experiments in Zero G plane? 18-24 sec Weightlessness 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 348183main_sts112_428-321.jpg
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