Question

Write short notes on exchange of gases in alveoli.

Answer 1

This is also known as external respiration. Here in the gaseous exchange oxygen passes from alveoli to pulmonary capillary blood and CO2.

The PCO2 or partial pressure of carbon dioxide in blood that reaches the alveolar capillaries is higher than PCO2 present in alveolar air.

Therefore, CO2 diffuses from the blood of alveolar capillaries into the alveolar air.

Exchange of gases occurs between the blood and tissue cells. This exchange happens through the tissue fluid which bathes these cells.

The blood that reaches tissue capillaries has high PO2 than that present in the tissue cells and PCO2 is lower than the tissue cells.