Altutide Physiology

Question 1

Describe the structure and composition of the atmosphere

Answer 1

1. Troposphere - av alt 36kft, weather, temperature - lapse rt: 1.98oC/1000ft until tropopause, pressure 1/£ altitude
2. Stratosphere: 158kft, where ozone is produced
3. Mesosphere: characterised by rapid decline in temp to -116oC at 129kft
4. Thermosphere: aka ionosphere, heating is caused by radiant sun energy, up to 1500oC, free electrons reflect radio waves- important for radio communication
5. Exosphere - true space

Question 2

What is the composition of the atmosphere?

Answer 2

N2 78% O2 21% CO2 0.03% other 0.97%

The fractional concentration of gas remains constant regardless of altitude

Question 3

Water vapour

Answer 3

Gases in contact with water will contain water vapour,

At 37oC WVP 47mmHg
At 100 oC WVP 760mmHg

Question 4

What’s 1 atmosphere equal to?

Answer 4

1013.25hPa = 14.7psi = 760 mmHg

Question 5

What are the physiological divisions of the atmosphere?

Answer 5

Physiological zones: MSL - 10kft, PAO2 sufficient time sustain life

Physiologically deficient zone: 10-50kft, hypoxia DCI, cold, need O2 systems, TUC affected

Space equivalent > 50kft - need pressure suits and cabin, 100% O2 is in sufficient to sustain life

Question 6

What is Armstrong’s line?

Answer 6

@63kft atmosphere P = 47mmHg = WVP of body fluids at 37 oC&raquo_space; water vapour can boil without addition of heat = embulism

Question 7

What are the 8 gas laws?

Answer 7

1. Charles law: kP, V £ T
   V1/T1= V2/T2
2. Armonton law: kV, P £ T
   P1/T1 = P2/T2
3. Boyle’s law: kT, P 1/£ V
   P1V1= P2V2
4. Daltons: Pt = p1+p2+p3…
5. Henry’s law: the solubility of a gas into a soln is £ to the PP of that gas above the soln, kT
6. Graham’s law: gas will diffuse down a pressure gradient from high to low
7. Ficks law: rate of gas movement £ SA, thickness and PP of O2
   Vgas = A/T x D(P1-P2) ; D £ sol/ MW
8. pascals law: pressure applied to an incompressible liquid will be distributed evenly amongst that liquid