FACTORS CONTROLLING EXCHANGE OF GASES IN ALVEOLAR CAPILLARIES

Intake of oxygen and release of carbon dioxide by blood passing through capillaries of alveoli is brought about by the following factors.

Difference in partial pressure of gases:

Diffusion of oxygen in and carbon dioxide out occurs because of difference in partial pressure of these gases.

Thin layers of capillaries:

Within the rich network of capillaries surrounding the alveoli, blood is distributed in extremely thin layers

Exposure to large alveolar surface:

Blood in capillaries is exposed to large alveolar surface.

Separation by thin membranes:

Blood in the lungs is separated from the alveolar air by extremely thin membranes of the capillaries and alveoli.