Question

Explain the dynamics of CO2 and O2 exchanges in A) the lungs and

B) the tissues in terms of partial pressures and chemical mechanisms.

Answer 1

A) Gas exchange occurs in the alveoli and capillaries of lungs. When oxygen is inhaled , it moves from the alveoli to the blood in the capillaries whereas carbon dioxide moves from the blood in the capillaries to the air in the alveoli.

B) There is low partial pressure of oxygen in tissues which is 40 mmHg due to continuous cellular respiration , it results in dissociation of oxygen from hemoglobin which creates a pressure gradient and diffuses out of the tissue crossing the interstitial space and enters the tissue. Talking about Carbon dioxide , it diffuses in the opposite direction since partial pressure is greater in the blood entering the lungs than it is in the alveolar air.