Chapter 4 - The Atmosphere, Oxygen and Respiration Flashcards
Why do humans need oxygen?
Oxygen is required in keeping cells alive.
How much CO2 is in the air?
Approximately 0.038%
Up to what altitude does gas volume percentage remain constant?
70000ft
What does Boyle’s law state?
For a enclosed amount of gas at a constant temperature, volume will decrease with an increase in pressure.
What does Charles law state?
At constant pressure, a volume of gas will increase with an increase in temperature.
What does Gay-Lussacs law state?
At a constant volume, pressure increases with temperature.
What is the combined gas law?
P1V1/T1 = P2V2/T2
What does Daltons law state?
The pressure of a gas is equal to the sum of the partial pressures of its constituent gases.
What does Henry’s law state?
The amount of a particular gas dissolved into a liquid is proportional to its partial pressure.
What does Ficks law state?
The rate of gas transfer through tissue is proportional to area of tissue and the pressure gradient and inversely proportional to thickness of tissue.
At what altitude is pressure 75% of MSL?
8000ft
At what altitude is pressure 50% of MSL?
18000ft
At what altitude is pressure 25% of MSL?
34000ft
What is the composition of air in the lungs?
Nitrogen - 75% Oxygen - 14% CO2 - 5% water vapour - 6%
What determines the amount of oxygen that gets diffused into the blood?
The partial pressure of oxygen in the lungs.
What is the approximate partial pressure of oxygen in the lungs and blood before diffusion?
100 in lungs 40 in blood
What is the role of haemoglobin?
Binds to and carries oxygen in the blood.
What is the minimum partial pressure of oxygen in the lungs before hypoxia ensues?
55mmHg
At what altitude do you need to start adding oxygen to the air to be avoid hypoxia?
10000ft
From what altitude is 100% oxygen required?
33700ft
At what altitude do you need to start pressurising the air to avoid hypoxia?
40000ft
Where in the lungs does diffusion of gases to and from the blood take place?
The Alveoli
How many breaths does an average healthy human male undergo each minute?
12 - 20 (16 on average)
What regulates the rate and depth of breaths?
Acidity of the blood due to CO2 levels (carbonic acid)
What is the tidal volume of the lungs and what is it for an average adult male?
The volume of air inhaled/exhaled in a normal breath.
Approximately 500ml.
What is the inspritory reserve and what is it for an average adult male?
The extra volume of air that the lungs can inhale over the tidal volume.
3100ml
What is the expritory reserve and what is it for an average adult male?
The volume of air that can be exhaled forcefully after the end of a normal tidal expiration.
1200ml
What is the residual volume and what is it for an average adult male?
The remaining air in the lungs after forceful expiration.
1200ml
What is the vital capacity the lungs?
Tidal volume + inspiratory volume + expiratory volume
What is total lung capacity?
Vital capacity + residual volume
What is functional residual capacity?
Residual volume + expiratory reserve volume
What is inspiratory capacity?
Tidal volume + inspiratory reserve volume
What is hypoxia?
A shortage of oxygen to cells for whatever reason.
What is hypoxic hypoxia?
Hypoxia associated with low saturation level of oxygen in the blood.
What is cabin pressure/altitude?
The pressure the cabin is raised to to acheive an effective altitude inside the cabin of around 6000 - 8000ft.
What is the pressure difference across a fueslage when at 8000ft cabin altitude?
465 mmHg / 9 psi
