Partial Pressure:

Pressure exerted by individual gases in a mixture of gases is called partial pressure.

Po₂ for oxygen and PCo₂ for carbon dioxide.

Rate for diffusion:-

Diffusion is the flow of a substance from its high to low concentration.

Diffusion is directly proportional to;

1. Thinness of membrane.
2. Surface area of membrane.
3. Permeability of membrane.
4. Partial pressure difference of gases on 2 side of membrane.

Binding of oxygen with hemoglobin displaces Co₂ from blood. This phenomenon is called Haldane effect.