Exchange of Gases - Process

Description:

Gaseous Exchange in the Lungs

Uptake of oxygen by pulmonary blood

• The partial pressure of gaseous oxygen in alveolar air on average is 104 mm Hg and in venous blood is 40 mm Hg.

• Initial pressure difference is 64 mm Hg which is responsible for the diffusion of oxygen into the pulmonary capillaries.

• After the diffusion the partial pressure of oxygen air becomes 95 mm Hg.

Uptake of carbon dioxide by alveolar air

• Partial pressure of carbon dioxide entering the pulmonary capillaries is 46 mm Hg and in alveolar air is 40 mm Hg.

• The difference of 6 mm Hg partial press is responsible for the diffusion of carbon dioxide into the alveolar air.

• The diffusion decreases the partial pressure of carbon dioxide in pulmonary capillary to about 40 mm Hg.

Gaseous exchange in the tissues

Uptake of oxygen by tissues

• Partial pressure of oxygen in arterial blood is 95 mm Hg and interstitial fluid is 20 mm Hg.

• High initial partial pressure difference causes rapid diffusion of oxygen from blood into tissues.

• Partial pressure of oxygen in blood falls to 40 mm Hg.

Uptake of carbon dioxide by

• Intra-cellular partial pressure of carbon dioxide is 45 - 68 mm Hg and in arterial blood is 40 mm Hg.

• Carbon dioxide diffuses rapidly from body cells to capillaries through tissue fluid.

• Partial pressure of carbon dioxide increases to 46 mm Hg in blood.