Question

The figure given above, shows a small part of human lung, where exchange of gases takes place. In which one of the option given below, the one part A, B, C or D is correctly identified along with its functions?

• A. B is red blood cell transport of $C{O}_2$ mainly.
• B. C is arterial capillary passes oxygen to tissues.
• C. A is alveolar cavity - main site of exchange of respiratory gases.
• D. D is capillary wall exchange of O${}_2$ and CO${}_2$ takes place here.

Answer 1

Answer: (C)

A is alveolar cavity - main site of exchange of respiratory gases.

The pulmonary alveoli are the terminal ends of the respiratory tree, which are the gas exchange sites. The alveolar membrane is the gas exchange surface. Carbon dioxide rich blood is pumped from the rest of the body into the alveolar blood vessels where, through diffusion, it releases its carbon dioxide and absorbs oxygen.

So, the correct answer is 'A is alveolar cavity - main site of exchange of respiratory gases.'