航天医学基础-introductiontospacel

1、Introduction to Space Life Sciences,Gilles Clment, Ph.D,CNRS Cerveau et Cognition Laboratory Toulouse, France,Kluwer Academic Publishers Copyright 2003 All rights reserved,Fundamentals of Space Medicine Chapter 1,Key Concepts,Space Life Sciences: What is it ? Where we are The historical context of h

2、uman spaceflight How we got there The importance of continuing research before long-duration exploration missions can be safely undertaken Where do we go from here,Space Life SciencesWhat is it,Life Sciences are specifically devoted to the working of the living world (from bacteria and plants to hum

3、ans) On Earth, all living organisms have developed as a result of constant exposure to 1-g gravity Space Life Sciences open a door to understanding ourselves, our evolution, the working of our world without the constraining barrier of gravity Beside microgravity, during space flight living organisms

4、 are also affected by ionizing radiation, isolation, confinement, changes in circadian rhythms (24-hr day/night cycle), etc. Objectives of space life sciences: Enhance fundamental knowledge in cell biology and human physiology Protect the health of astronauts Develop advanced technology and applicat

5、ions for space and ground-based research,Justification for Human Spaceflight,Robotics versus Human crews = Apples versus Oranges Human Pros: intelligent operators, efficient end-effectors Human Cons: expensive,complexity of habitable environment Human spaceflight critics often discount the value of

6、Life Sciences on the “Discovery Ledger (Big Book)” often due to following fundamentals differences: Physical Sciences: more concrete discoveries in relatively unexplored sphere Life Sciences: an inherently inexact science; context of background physiological variability; requirement for repeated mea

7、surements,Photo NASA,Space Medicine versus Space Physiology,Space Medicine To solve medical problems encountered in spaceflight Includes some adaptive changes (e.g., space motion sickness), environmental exposures, etc. Includes also some non-pathologic changes which become maladaptive on return to

8、Earth (e.g., bone loss) Outlook is operational, views problems/peculiarities from standpoint of mission impact Space Physiology To characterize response to space, especially 0-G Necessary knowledge base for above Outlook is investigational, views problems/peculiarities from standpoint of scientific

9、return,Where we are (as of 1st July 03),Photo CNES,Total number of persons who have flown in space: 433 (41 ) Cumulative spaceflight time: 72 years (26.410 days) Mean spaceflight duration: 28 days Cumulative spaceflight duration by individual: Polyakov (679 days; 2 flights) Avdeyev (748 days; 3 flig

10、hts) Re-adaptation to Earth gravity stated to be 90% complete after 6 years Valery Polyakov (during a science conference) How did we get there?,22 months,25 months,1783: Two French gentlemen ride a hot-air (Montgolfier) balloon,Major Space Life Sciences Events,1951: First successful (non-orbital) fl

11、ight of a sounding rocket with a monkey and 11 mice (previous attempts since 1948 were not successful),1957: Dog Laika first living creature into orbit (died after a few days)followed by monkeys,Photo CNES,1959: Selection of 7 American astronauts,Major Space Life Sciences Events,1960: Selection of 1

12、1 Soviet cosmonauts,Photo NASA,Photo RSA,1965: First space walk (Extra-Vehicular Activity),1961: First human to orbit the Earth (Y. Gagarin) 1963: First woman (V. Tereshkova) in spacesecond Russian woman (S. Savitskaya) did not fly until 1982,Major Space Life Sciences Events,1965-66: Longest stay in

13、 space is 14 days (Gemini 7) first observations on human body adaptation artificial gravity first tested (Gemini 11),Major Space Life Sciences Events,70s : Salyut, Skylab start of detailed SLS investigations,1981: First space vehicle piloted during return (Shuttle),Photos NASA,2000: First expedition

14、 crew on board ISS,1994: Longest stay in space is 14 months (MIR),Human Spaceflight Experience,Adapted from Reschke and Sawin (2003),Human Spaceflight Experiencegreater than 30 days,Humans in Space,First space missions were to demonstrate that humans could survive a journey into space Some people do

15、ubted whether humans could endure the g forces of launch and re-entry, or swallow, or sleep in the absence of gravity Some predicted that the bowels would not work without gravity, the heart might cavitate like a pump, or become so weakened as to prohibit return to Earth,How long can humans live in

16、space, and how effectively can they work in space are still open questions Living and working is far different from merely surviving After extended stays in space, can people return safely to Earth and lead normal, healthy lives? Such questions are much more difficult than questions of survival beca

17、use they require sophisticated scientific experimentation,Movie: 13_impossi,Surviving the Odyssey,What Really Occurs,No up or down disorientation, nausea,Fluids shift towards head puffy face, sinus congestion, headache, changes in smell and taste,Antigravity postural (extensor) muscles not used new

18、locomotion pattern, chicken legs, muscle strength and endurance decrease,Photos NASA,What Really Occurs,Bone density decreases by 1-3% per month,No up or down disorientation, nausea Fluids shift towards head puffy face, sinus congestion, headache, changes in smell and taste Antigravity postural (ext

19、ensor) muscles not used new locomotion pattern, chicken legs, muscle strength and endurance decrease,Fluids volume decreases changes in heart volume, heart rate, and blood pressure, breathing difficult (less red blood cells),What Really Occurs,Intervertebrate disks less compressed height increases,

20、back pain,Sleep disorders,No up or down disorientation, nausea Fluids shift towards head puffy face, sinus congestion, headache, changes in smell and taste Antigravity postural (extensor) muscles not used new locomotion pattern, chicken legs, muscle strength and endurance decrease Fluids volume decr

21、eases changes in heart rate and blood pressure, breathing difficult (less red blood cells) Bone loss,Adapted from Lujan and White (1994),Photo NASA,No up or down disorientation, nausea Fluids shift towards head puffy face, sinus congestion, headache, changes in smell and taste Antigravity postural (

22、extensor) muscles not used new locomotion pattern, chicken legs, muscle strength and endurance decrease Fluids volume decreases changes in heart rate and blood pressure, breathing difficult (less red blood cells) Bone loss Intervertebrate disks less compressed height increases, back pain Sleep disor

23、ders,What Really Occurs,Psychological troubles,Sharper vision, but light flashes (radiation),Photo NASA,Photo NASA,Issues for Human Missions,Preflight: Astronaut selection, crew selection, medical training Inflight: Acceleration, vibration, noise during launch and landing,Movie: 19_launch,Preflight:

24、 Astronaut selection; crew selection; medical training Inflight: Acceleration; vibration; noise during launch and landing,Psycho-sociological issues (support) Environmental issues: toxic substances, pressure changes Extra-Vehicular activity (EVA): strain on muscles and bones, decompression-related d

25、isorders,Physiological adaptation: heart (dys-rhythmias) and blood vessels, muscles (strength), bones (fractures, renal stones), nervous system, immune system (infection),Radiation (sterility, cancer),Crew medical officer: diagnosis, treatment (surgery),Emergency return,Issues for Human Missions,Iss

26、ues for Human Missions,Postflight: Piloting 1-g feels like 4-g Emergency egress Standing: orthostatic intolerance Walking: postural instability Motion sickness (Mal de Dbarquement) Muscle and bone weakness Decreased exercise capacity Return to flight status,Photo NASA,Countermeasures,2 daily 1-hour

27、sessions of exercise: Treadmill with axial loading Cycle ergometer Resistive exercise Traction on “bungee cords” Low Body Negative Pressure Fluid loading before re-entry,Photos NASA,Human Mars Mission,Challenges for a Mars Mission,Crew selection Onboard medical officer Radiation dose Bone loss Advan

28、ced Life Support Systems,Spaceflight Life Support,Human requirements Hygiene, sanitation Nutrition (adequate, appealing) Rest (avoid chronic fatigue) Exercise (fitness, recreation, motivation) Human performance (psycho- social, workload, circadian factors) Life support systems Atmosphere, temperatur

29、e, lighting, noise Food, waste From physico-chemical (recycled) to bioregenerative (ecologically closed) Biosphere 2 Mir Greenhouse Bio-Plex,Photo NASA,Photo ESA,Greenhouse in Space,Critical questions to be addressed : How far can we reduce reliance on expendables? How well do biological and physico

30、-chemical life support technologies work together over long periods of time? Is a “steady state” condition ever achieved with biological systems? How do various contaminants accumulate and what are the long-term cleanliness issues?,Photo NASA,Challenges,Short-duration spaceflights presumably OK for

31、tourists For long-duration missions, the MIR experience indicates that current inflight countermeasures are not optimal Using the current countermeasures methods, humans would not be operational after landing on Mars Artificial gravity probably the most efficient countermeasure,Photo CNES,Movie: 27_

32、cosmonaut,Artificial Gravity,Principle of centrifugation,For interplanetary travel the design is most likely to be a short-arm centrifuge. combined with muscular exercise,Criteria for comfort (less motion sickness with lower angular velocity; low velocity means large radius),Recommended zone for eff

33、ective human performance in rotating space systems,Photo NASA,Movie: 28_centrifuge,Movie: 28_hyperg,Future Research,Changes seen at cellular level. However, too much publicity on biochemical factories in space Plants in space. Life support systems: how to move from physico-chemical to closed ecologi

34、cal life support systems Human Mars mission. Probably the longest period away from Earth to date; also probably the longest exposure to hypogravity (1/3 g) environment to date,Think about development of insects, amphibians, mammals after several generations without perceived gravity,Space Life Scien

35、ces research is on hold now,ISS should be ideal for study of fundamental biological processesnew science: gravitational physiology; no Nobel prize yet, but given prizes have been challenged,Document NASDA,Photo NASA,Movie: 29_frog,Benefits of SLS Research,Biology Improve overall health of people of

36、all ages Improve crop yields using less nutrients and smaller surface Advance understanding of cell behavior Biotechnology Provide information to design a new class of drugs to target specific proteins and cure specific diseases Culture tissue for use in cancer research/surgery and bone and cartilage injuries Biomedical Research Enhance medical understanding of the role of force on bone in disease processes including osteoporosis