Intro To Altitude Physiology

Question 1

Describe the structure atmosphere

Answer 1

Troposphere - <58000ft
- cold to the tropopause
Stratosphere - 58-158000Ft
- contains Ozone layer
- warms up to stratopause
Mesosphere - 158 - 290000ft
- cold until the mesopause
Thermosphere - 290-700000ft
- warms up again
Exosphere >700000ft

Question 2

Describe the composition of atm

Answer 2

• Oxygen 21%
• Nitrogen 78%
• Other gases
  — argon
  —CO2
  —Water vapour

Question 3

Function of Atmosphere

Answer 3

Radiation protection from ionising and ultraviolet. Eg layers of ATM and Ozone .
Thermal protection - natural greenhouse effect.
Support of life - Oxygen is being key.

Question 4

Dalton’s law

Answer 4

Total pressure of a mixture of gases is equal to the sum of the partial pressure of each of the constituent gases.

Question 5

Measurement of Pressure

Answer 5

MSL = 760mmHg = 1013.2hPa = 1bar = 14.7 psi

Question 6

Lapse rate of temp in altitude

Answer 6

1.98 degree/1000ft up to 36089ft

Question 7

% of Atm at different altitudes

Answer 7

Exponential decrease of pressure with increasing altitude.
At 18000ft = 50% atm
25000ft = 33% atm
35000ft = 25% atm
55000ft = 10% atm

Question 8

Armstrong’s limit

Answer 8

63000ft
Atm pressure = 47mmHg
Boiling point of water vapour
Body boils

Question 9

Characterise the risk of radiation exposure for aircrew given different condition of latitude and altitude

Answer 9

Higher = more particular
Galactic and solar
Protons, alpha particles and heavy nuclei, gamma
Secondary radiation from collision with ATM and aircraft
Depends of location eg magnetic fields
Average aircrew dose 3-4mSv per year
Occupation limit 20mSv per year

Question 10

Describe the different zones

Answer 10

MSL - 10000ft =. Physiology Zone

10000-50000ft = Physiologiical deficient zone

> 50000ft = space equivalent zone

Question 11

Boyle’s law

Answer 11

At constant temperature pressure is inversely proportional to volume

Question 12

Henry’s law

Answer 12

Constant temp, amount of gas dissolves is directly proportional to partial pressure of the gas

Question 13

Gay- Lussac’s law

Answer 13

states that the pressure of a given mass of gas varies directly with the absolute temperature of the gas, when the volume is kept constant.

Question 14

Charles’ law

Answer 14

Volume is directly proportional to its absolute temperature at constant pressure.

Question 15

Combined gas law

Answer 15

(P1V1)/T1=(P2V2)/T2

Question 16

Pascal’s principle

Answer 16

Pressure applied to an incompressible liquid will be transmitted equally throughout the liquid

Question 17

Fick’s law

Answer 17

Vgas = (A/T) D (P1-P2)

A surface area
D = Solubility/square root of molecular weight

Question 18

What are the aeromedical relevant laws

Answer 18

Boyle’s law
Dalton’s law
Henry’’s law
Graham Law

Question 19

Graham’s Law

Answer 19

Rate of effusion of a gas in inversely proportional to the square root of the mass of its particles.

Question 20

Explain how the gas law’s affect physiology at Altitude.

Answer 20

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