the total pressure of a gas mixture is equal to the sum of the pressure that each gas would exert independently.
partial pressure of oxygen.
in air - 20.93%.
expressed as a fraction- 0.2093.
about 159 mmHg
(^ in altitude = lower P)
In Water (Scuba Diving):
When you are deep in water you can feel the pressure build up in your ears.
Fick's Law of Diffusion
The rate of gas transfer (V gas) is proportional to the tissue area, the diffusion coefficient of the gas, and the difference in the partial pressure of the gas on the two sides of the tissue and inversely proportional to tissue thickness.
Vgas = (A/T) * D (P1-P2)
A= tissue area
T= tissue thickness
D= diffusion coefficient (Constant for each gas!!)
p1-p2= difference in partial pressures
Blood flow to the lung:
same rate of flow as systemic circuit
Most of the air is expelled after only 1 second. (FEV1)