EFFECTS OF MICROGRAVITY

1. EFFECTS OF MICROGRAVITY

2. ACCELERATION • FIRST PROBLEM ASTRONAUTS FACE • SPEED IS NOT A PROBLEM • YOU ARE CURRENTLY TRAVELING AT APPROXIMATELY 67,000 MPH THROUGH SPACE AS THE EARTH ORBITS THE SUN AND SPINNING AT APPROXIMATELY 1,000 MPH AS THE EARTH TURNS ON ITS AXIS

3. • ACCELERATION IS MEASURED IN TERMS OF G-FORCE WHERE 1 G IS THE PULL OF THE GRAVITY ON THE SURFACE OF THE EARTH • GRAVITY = 9.806 N/KG • 1 NEWTON = FORCE REQUIRED TO GIVE A MASS OF 1 KG AN ACCELERATION OF 1 M/SEC/SEC (1 METER PER SECOND SQUARED)

4. GREATEST G FORCE OCCURS AS: • THE SPACECRAFT ACCELERATES AS IT ENTERS ORBIT WHEN IT IS MUCH LIGHTER (MOST OF THE FUEL HAS BEEN USED) AND THE ROCKETS ARE STILL AT FULL THRUST • THE SPACECRAFT DECELERATES DURING RE-ENTRY INTO THE EARTH’S ATMOSPHERE

5. EFFECTS OF INCREASED G FORCE • 2 G - BODY FEELS HEAVIER, FACIAL TISSUES SAG, AND IT IS DIFFICULT TO STAND-UP FROM SITTING POSITION • 3G - IMPOSSIBLE TO STAND AND COLOR VISION FADES AS A GRAY CURTAIN SETS IN AS G-FORCE FURTHER INCREASES • 4.5 G - VISION IS LOST • 8 G - IMPOSSIBLE TO RAISE ARMS OR LIFT HEAD • 12 G - CONSCIOUSNESS LOST

6. EFFECTS OF INCREASED G FORCE • G FORCE PULLS BLOOD INTO LOWER EXTREMITIES, HEART CAN NOT COMPENSATE, AND UNCONSCIOUSNESS OCCURS • GAS EXCHANGE ALSO DECREASES AS DIAPHRAGM IS PULLED DOWNWARD RESULTING IN BREATHING DIFFICULTY AND DECREASED ALVEOLAR VENTILATION

7. NOTE: AN ADDITIONAL PROBLEM AT TAKE-OFF IN ADDITION TO THE INCREASED G FORCE IS THE SEVERE VIBRATIONS RESULTING IN IMPAIRED ABILITY TO PERFORM MANUAL TASKS, NAUSEA, HYPERVENTILATION, AND PHYSICAL COLLAPSE

8. EFFECTS OF WEIGHTLESSNESS

9. EFFECTS OF WEIGHTLESSNESS • ASTRONAUTS GROW TALLER • DECREASED RED BLOOD CELL PRODUCTION AS (1) THE SHIFT OF BLOOD TO THE CHEST TRICKS THE BODY INTO THINKING THAT IT HAS TOO MUCH BLOOD VOLUME, WHICH LEADS TO A DECREASE IN ERYTHROPOIETIN RELEASED FROM THE KIDNEYS AND HENCE RBC SYNTHESIS BY THE BONE MARROW AND (2) RBCs WAITING TO BE RELEASED FROM THE BONE MARROW ARE DESTROYED

10. EFFECTS OF WEIGHTLESSNESS • DECREASED BLOOD VOLUME NOTE: THE INCRESED BLOOD VOLUME IN THE THORACIC CAVITY DUE TO FLUID SHIFTS INCREASES BLOOD PRESSURE, WHICH LEADS TO DECREASED ANTI-DIURETIC HORMONE (ADH) AND ALDOSTERONE RELEASE AS WELL AS DECREASED SNS ACTIVITY RESULTING IN INCREASED URINE PRODUCTION AND DECREASED BLOOD VOLUME

11. EFFECTS OF WEIGHTLESSNESS • DECREASED OXYGEN CARRYING CAPACITY OF THE BLOOD • INCREASED BLOOD VISCOSITY WHICH INCREASES RESISTANCE TO BLOOD FLOW • INCREASED RESISTANCE TO BLOOD FLOW POTENTIALLY DECREASES CARDIAC OUTPUT AND/OR INCREASES BLOOD PRESSURE • DECREASED PHYSICAL WORK CAPACITY

12. EFFECTS OF WEIGHTLESSNESS • LOSS OF LEAN BODY WEIGHT (BONE, MUSLCE, AND CONNECTIVE TISSUE) AND CARDIAC TISSUE WHICH ALSO CONTRIBUTES TO A DECREASE IN PHYSICAL WORK CAPCITY • BONE LOSS DUE TO REDUCED BONE STRESS • MUSCLE LOSS DUE TO REDUCED USE • CARDIAC ATROPHY DUE TO DECREASED BLOOD VOLUME AND DECREASED GRAVITATIONAL PULL • ASTRONAUTS EXERCISE SEVERAL HOURS PER DAY IN ORDER TO MINIMIZE LOSS OF LEAN BODY WEIGHT AND CARDIAC TISSUE

13. EFFECTS OF WEIGHTLESSNESS • SLEEP DIFFICULTY DUE TO LITTLE SENSE OF PRESSURE AND HENCE SECURITY • ASTRONAUTS SLEEP IN SLEEPING BAGS ATTACHED TO WALLS WITH HEAD AND KNEE STRAPS TO INCREASE SENSE OF PRESSURE • NEED TO SLEEP IN VENTILATED AIR FLOW TO INSURE THAT EXHALED CO2 IS NOT RE-INHALED

14. EFFECTS OF WEIGHTLESSNESS • INCREASED SPREAD OF INFECTIOUS DISEASES AS BACTERIA FROM SKIN AND SNEEZES/COUGHS FLOATS IN CIRCULATING AIR FOR LONGER PERIODS OF TIME WITHOUT GRAVITY • SPACE SICKNESS (HEADACHES, NAUSEA, DIZZINESS, LOSS OF APPETITIE, LACK OF MOTIVATION, DROWINESS, AND IRRITABILITY) DUE TO TILTING THE HEAD FORWARD OR BACKWARD OR A VISUALLY DISORIENTATING SCENE

15. COSMIC RADIATION • ON EARTH THE ATOMOSHERE AND EARTH’S MAGNETIC FIELD SHIELDS MOST RADIATION EXCEPT FROM VISABLE LIGHT AND RADIO WAVES • THREE SOURCES OF EXTRETERRESTRIAL RADIATION THAT ASTRONAUTS EXPERIENCE ARE GALATIC RAYS, SOLAR RADIATION, TRAPPED BELT RADIATION (E.G., VAN ALLEN BELT THAT ENCIRCLES EARTH LIKE A HOLLOW DONUT)

16. COSMIC RADIATION • RADIATION LEVELS ARE USUALLY LOW • LONG TERM EXPOSURE MAY: • DAMAGE GENETIC MATERIAL (DNA) THEREBY INCREASING THE RISK OF CANCER • DAMAGED GERM CELLS (SPERM AND EGG CELLS) MAY CAUSE INFERTILITY OR GENETIC ABNORMALITIES IN THE CHILDREN OF ASTRONAUTS

17. COSMIC RADIATION • ASTRONAUTS CARRY RADIATION DOSIMETERS • RADIATION EXPOSURE IS USUALLY WITHIN ACCEPTABLE LIMITS ALTHOUGH ASTRONAUTS WHO SPEND A LONG TIME IN SPACE CRAFTS OR WORK STATIONS MAY HAVE RECEIVED A SIGNIFICANT DOSE • SUPERSONIC AIRCRAFTS (E.G., CONCORDE) CRUISE CLOSE TO THE EDGE OF THE EARTH’S ATMOSPHERE AND ARE NOT SHIELDED FROM COSMIC RADIATION, ALTHOUGH IT WOULD TAKE 14 ROUND TRIP FLIGHTS FROM LONDON TO NEW YORK TO REACH TOXIC LEVELS

18. SOLAR FLARES

19. SOLAR FLARES

20. SOLAR FLARES • VERY HIGH INTENSITY RADIATION • KILLS CELLS OUTRIGHT • DEATH MAY OCCUR WITHIN HOURS DUE TO DAMAGE TO THE CENTRAL NERVOUS SYSTEM OR WITHIN A FEW DAYS DUE TO DESTRUCTION OF WHITE BLOOD CELLS OR THE RAPIDLY-DIVIDING CELLS THAT LINE THE INTESTINAL WALLS

21. RETURNING TO EARTH • UNABLE TO STAND WITHOUT FAINTING (I.E., FAILURE OF THE ORTHOSTATIC TOLERANCE TEST) DUE TO: • FLUID SHIFTS BACK TO LOWER EXTREMITIES DUE TO GRAVITY • BLOOD VOLUME IS DECREASED • MUSCLE PUMPING IS IMPAIRED DUE TO LOSS OF MUSCLE MASS • THEREFORE, POOLING OF BLOOD OCCURS IN THE LOWER EXTREMITIES WHICH DECRESES END-DIASTOLIC VOLUME, STROKE VOLUME, AND CARDIAC OUTPUT

22. RETURNING TO EARTH • LOSS OF MUSCLE MASS MAKES IT DIFFICULT TO WALK • DIFFICULT TO MAINTAIN BALANCE OR REMAIN UPRIGHT WITH EYES CLOSED • DIZZINESS AND NAUSEA • INCREASED RISK OF INJURY

23. RETURNING TO EARTH • MOVEMENT OF HEAD RESULTS IN FALSE ILLUSIONS THAT THE WORLD, RATHER THAN THE HEAD, IS MOVING, SUGGESTING THAT SIGNALS FROM RECEPTORS IN THE SEMICIRCULAR CANALS OF THE EARS (WHICH RESPOND TO LINEAR ACCLERATION) NEED TO BE RE-PROGRAMMED BACK FROM A MICROGRAVITY ENVIRONENT TO A GRAVITATIONAL ENVIRONMENT

24. QUESTIONS??

25. CARDIOVASCULAR SYSTEM IN SPACE HOW DOES WEIGHTLESSNESS IN SPACE AFFECT • BODY FLUID DISTRIBUTION? • BLOOD VOLUME? • RED BLOOD CELL LEVEL? • MUSCLE AND BONE MASS? • IMMUNE SYSTEM? • FACIAL EDEMA? • LEG SHAPE?

26. CARDIOVASCULAR SYSTEM IN SPACE HOW DOES WEIGHTLESSNESS IN SPACE AFFECT • MOTION SICKNESS? • EXERCISE CAPACITY? • HEADACHES? • POST-FLIGHT ORTHOSTATIC TOLERANCE? KNOW AND UNDERSTAND IN GENERAL HOW RESEARCH FOR WEIGHTLESSNESS IN SPACE MAY HELP SOLVE MEDICAL AND HEALTH PROBLEMS ON EARTH.

27. MUSCULOSKELETAL SYSTEM IN SPACE HOW DOES WEIGHTLESSNESS IN SPACE AFFECT • WEIGHT-BEARING WEAKNESSES IN MUSCLE, CARTILAGE, AND BONE? • HEAVY WORK IN SPACE? • MUSCLE ATROPHY? • MUSCLE TONE AND STRENGTH? • MUSCLE FATIGUE? • MUSCLE SYNERGISM? • MOTOR CONTROL?

28. MUSCULOSKELETAL SYSTEM IN SPACE HOW DOES WEIGHTLESSNESS IN SPACE AFFECT • MOTOR-END PLATE DEGENERATION? • CONTRACTION VELOCITY? • BONE MINERALIZATION? • CONNECTIVE TISSUE? • BACK PAIN? KNOW AND UNDERSTAND IN GENERAL HOW RESEARCH FOR WEIGHTLESSNESS IN SPACE MAY HELP SOLVE MEDICAL AND HEALTH PROBLEMS ON EARTH.