Chapter 4 - The Atmosphere, Oxygen and Respiration

Question 1

Why do humans need oxygen?

Answer 1

Oxygen is required in keeping cells alive.

Question 2

How much CO2 is in the air?

Answer 2

Approximately 0.038%

Question 3

Up to what altitude does gas volume percentage remain constant?

Answer 3

70000ft

Question 4

What does Boyle’s law state?

Answer 4

For a enclosed amount of gas at a constant temperature, volume will decrease with an increase in pressure.

Question 5

What does Charles law state?

Answer 5

At constant pressure, a volume of gas will increase with an increase in temperature.

Question 6

What does Gay-Lussacs law state?

Answer 6

At a constant volume, pressure increases with temperature.

Question 7

What is the combined gas law?

Answer 7

P1V1/T1 = P2V2/T2

Question 8

What does Daltons law state?

Answer 8

The pressure of a gas is equal to the sum of the partial pressures of its constituent gases.

Question 9

What does Henry’s law state?

Answer 9

The amount of a particular gas dissolved into a liquid is proportional to its partial pressure.

Question 10

What does Ficks law state?

Answer 10

The rate of gas transfer through tissue is proportional to area of tissue and the pressure gradient and inversely proportional to thickness of tissue.

Question 11

At what altitude is pressure 75% of MSL?

Answer 11

8000ft

Question 12

At what altitude is pressure 50% of MSL?

Answer 12

18000ft

Question 13

At what altitude is pressure 25% of MSL?

Answer 13

34000ft

Question 14

What is the composition of air in the lungs?

Answer 14

Nitrogen - 75% Oxygen - 14% CO2 - 5% water vapour - 6%

Question 15

What determines the amount of oxygen that gets diffused into the blood?

Answer 15

The partial pressure of oxygen in the lungs.

Question 16

What is the approximate partial pressure of oxygen in the lungs and blood before diffusion?

Answer 16

100 in lungs 40 in blood

Question 17

What is the role of haemoglobin?

Answer 17

Binds to and carries oxygen in the blood.

Question 18

What is the minimum partial pressure of oxygen in the lungs before hypoxia ensues?

Answer 18

55mmHg

Question 19

At what altitude do you need to start adding oxygen to the air to be avoid hypoxia?

Answer 19

10000ft

Question 20

From what altitude is 100% oxygen required?

Answer 20

33700ft

Question 21

At what altitude do you need to start pressurising the air to avoid hypoxia?

Answer 21

40000ft

Question 22

Where in the lungs does diffusion of gases to and from the blood take place?

Answer 22

The Alveoli

Question 23

How many breaths does an average healthy human male undergo each minute?

Answer 23

12 - 20 (16 on average)

Question 24

What regulates the rate and depth of breaths?

Answer 24

Acidity of the blood due to CO2 levels (carbonic acid)

Question 25

What is the tidal volume of the lungs and what is it for an average adult male?

Answer 25

The volume of air inhaled/exhaled in a normal breath. Approximately 500ml.

Question 26

What is the inspritory reserve and what is it for an average adult male?

Answer 26

The extra volume of air that the lungs can inhale over the tidal volume. 3100ml

Question 27

What is the expritory reserve and what is it for an average adult male?

Answer 27

The volume of air that can be exhaled forcefully after the end of a normal tidal expiration. 1200ml

Question 28

What is the residual volume and what is it for an average adult male?

Answer 28

The remaining air in the lungs after forceful expiration. 1200ml

Question 29

What is the vital capacity the lungs?

Answer 29

Tidal volume + inspiratory volume + expiratory volume

Question 30

What is total lung capacity?

Answer 30

Vital capacity + residual volume

Question 31

What is functional residual capacity?

Answer 31

Residual volume + expiratory reserve volume

Question 32

What is inspiratory capacity?

Answer 32

Tidal volume + inspiratory reserve volume

Question 33

What is hypoxia?

Answer 33

A shortage of oxygen to cells for whatever reason.

Question 34

What is hypoxic hypoxia?

Answer 34

Hypoxia associated with low saturation level of oxygen in the blood.

Question 35

What is cabin pressure/altitude?

Answer 35

The pressure the cabin is raised to to acheive an effective altitude inside the cabin of around 6000 - 8000ft.

Question 36

What is the pressure difference across a fueslage when at 8000ft cabin altitude?

Answer 36

465 mmHg / 9 psi