Question

Exchange of gases in the body takes place by which of the following mechanisms?

• A. External respiration
• B. Internal respiration
• C. Cellular respiration
• D. Counter-current exchange

Answer 1

The correct option is B

Internal respiration

Diffusion is the movement of a substance from an area of high concentration to an area of low concentration. The exchange of gases take place in the millions of alveoli in the lungs and the capillaries that envelop them. Due to the difference in concentration, inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli.