Question

The figure given below shows a small part of human lung where exchange of gases takes place. Select the option which represents labelled part (a, b, c or d) correctly identified along with its function.

• A. c : Arterial capillary - passes oxygen to tissues
• B. a : Alveolar cavity - main site of exchange of respiratory gases
• C. d : Capillary wall - exchange of $O_2$ and $C{O}_2$ takes place here
• D. b : Red blood cells - carry out transport of $C{O}_2$ only

Answer 1

The correct option is B a : Alveolar cavity - main site of exchange of respiratory gases

The labelled part a represents alveolar cavity. A pulmonary alveolus is a hollow cup-shaped cavity found in the lung parenchyma where gas exchange take place. Lung alveoli are found in the acini at the beginning of the respiratory zone.

So, option B is the correct option.