Gas Exchange

The rate of gas exchange depends on:
1. Partial pressure of the gases
2. Solubility of the gases
3. Surface area
4. Diffusion distance
Partial Pressure
Partial pressure is the pressure exerted by and individual in a mixture of gases.
For example atmospheric pressure = 760 mm Hg
% of O₂ of in Atmosphere = 20.95%
P_O2 =20.95% of 760 mmHg = 159 mmHg
A gas always diffuses from the region of its higher partial pressure to the region of its partial pressure.

Gas	Atm.Air	Alveoli	Deoxygenated Blood	Oxygenated Blood	Tissues
O2	159	104	40	95	40
CO2	0.3	40	45	40	45

All units in mmHg.