Aerospace Physiology MARYLAND. Cardiopulmonary Physiology. Musculoskeletal Vestibular Neurological. Respiratory Cardiovascular U N I V E R S I T Y O F

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2 The Human Circulatory System

3 Lung Measurements From Roy DeHart, Fundamentals of Aerospace Medicine, Lea & Febiger, 1985

4 Blood Pressure in Circulatory System

5 Gas Exchange in the Lungs From Roy DeHart, Fundamentals of Aerospace Medicine, Lea & Febiger, 1985

6 Gas Exchange in the Tissues From Roy DeHart, Fundamentals of Aerospace Medicine, Lea & Febiger, 1985

7 Metabolic Processes Respiratory Quotient ( RQ ) Function of activity and dietary balance Sugar: Protein: Fat: RQ = Exhaled volume of CO 2 Inhaled volume of O 2 C 6 H 12 O 6 + 6O 2 Æ 6CO 2 + 6H 2 O RQ =1.0 For well-balance diet RQ~0.85 ( ) ( ) ( ) 2C 3 H 7 O 2 N + 6O 2 Æ 5CO H 2 O RQ = 0.83 C 57 H 104 O O 2 Æ 57CO H 2 O RQ = 0.71

8 Respiratory Problems Hypoxia Hypoxic Hypemic Stagnant Histotoxic Hyperoxia Hypocapnia Hypercapnia

9 Types of Hypoxia Hypoxic (insufficient O 2 present) Decompression Pneumonia Hypemic (insufficient blood capacity) Hemorrhage Anemia Stagnant (insufficient blood transport) Excessive acceleration Heart failure Histotoxic (insufficient tissue absorption) Poisoning

10 Alveolar Pressures From Roy DeHart, Fundamentals of Aerospace Medicine, Lea & Febiger, 1985

11 Effects of Supplemental Oxygen From Roy DeHart, Fundamentals of Aerospace Medicine, Lea & Febiger, 1985

12 Hypoxia Effective Performance Time From Roy DeHart, Fundamentals of Aerospace Medicine, Lea & Febiger, 1985

13 Oxygen Toxicity From Roy DeHart, Fundamentals of Aerospace Medicine, Lea & Febiger, 1985

14 Gravity Effects on Arterial Pressure 320 mm 95/55 mmhg 120/80 mmhg 1200 mm 1000 mmh 2 O = 74.1 mmhg 210/170 mmhg

15 The Human Circulatory System, Revisited

16 Cardiovascular Effects of Microgravity Cardiovascular deconditioning Upper body blood pooling Changes in blood volume Increased calcium content

17 Acceleration Effects on Arterial Pressure 320 mm 25/ mmhg 120/80 mmhg 1200 mm At 4 g s longitudinal: 1000 mmh 2 O = 296 mmhg 475/435 mmhg

18 Decompression Sickness Release of dissolved gases in blood following pressure drop DCS, Caisson Disease, The Bends J. B. S. Haldane modeled DCS as supersaturation of dissolved nitrogen in blood: R = P N 2 = 0.79 (nominally) P ambient Experience indicates symptomatic DCS onset at levels of

19 Haldane Tissue Model Hypothesized that tissues absorb and release dissolved gases at exponential rates dp tissue dt = k( P alveoli - P ) tissue Response to a step change in alveolar pressure P tissue (t) = P tissue,0 + ( P alveoli - P )( tissue 1- e -kt )

20 Tissue Models, continued Rate coefficient frequently given as time to evolve half of dissolved gases: T 1/2 = ln(2) k Workman added concept of M-values - critical saturation limits for tissues Continued refinement of tissue models for predicting onset of DCS

21 PADUA (Univ of Pennsylvania) Tissue Model Tissue T 1/2 (minutes) M 0 (bar)

22 Tissue Saturation following Descent

23 Tissue Saturation after Ascent

24 Bubble Formation and Growth In equilibrium, external pressure balanced by internal gas pressure and surface tension Surface tension forces inversely proportional to radius UNIVERSITY OF

25 Vestibular System From Roy DeHart, Fundamentals of Aerospace Medicine, Lea & Febiger, 1985

26 Vestibular Sense Organs From Roy DeHart, Fundamentals of Aerospace Medicine, Lea & Febiger, 1985

27 Otolith Responses From Roy DeHart, Fundamentals of Aerospace Medicine, Lea & Febiger, 1985

28 Artificial Gravity g rotation =w 2 r Lunar gravity Mars gravity 0.5*Earth gravity 0.75*Earth gravity Earth gravity Rotation Rate (rpm)

29 Allowable Rotation Rates Select groups (highly trained, physically fit) can become acclimated to 7 rpm 95% of population can tolerate 3 rpm Sensitive groups (elderly, young, pregnant women) may have tolerance levels as low as 1 rpm

30 Short-Term Dose Radiation Effects rem - minor blood changes rem 5-10% minor nausea and vomiting rem 25-50% nausea and vomiting 50% reduction in lymphocytes rem Nausea, vomiting, diarrhea, minor hemorrhage 75% reduction in all blood cells 5-50% incidence of death

31 Short-Term Dose Radiation Effects rem Nausea, vomiting, diarrhea, hemorrhage, emaciation 75% reduction in all blood cells 50-90% mortality within 6 weeks 6 month convalescence rem Nausea and vomiting within four hours Mortality approaching 100% survival time <2 weeks incapacitation within hours

32 NASA Radiation Dose Limits

33 References R. L. DeHart, ed., Fundamentals of Aerospace Medicine, Second Edition Williams and Wilkins, 1996 A. E. Nicogossian, C. L. Huntoon, and S. L. Pool, Space Physiology and Medicine, Third Edition Lea and Febiger, 1994 A. E. Nicogossian, S. R. Mohler, O. G. Gazenko, and A. I. Grigoriev, eds., Space Biology and Medicine (Volume III, Book 1: Humans in Spaceflight) American Institute of Aeronautics and Astronautics, 1996 J. T. Joiner, ed., NOAA Diving Manual: Diving for Science and Technology, Fourth Edition Best Publishing, 2001

Review of iterative design approach Respiratory Cardiovascular Musculoskeletal Vestibular Neurological

Review of iterative design approach Respiratory Cardiovascular Musculoskeletal Vestibular Neurological 2001 David L. Akin - All rights reserved http://spacecraft.ssl.umd.edu Overview of the Design Process