Question

Which among the following is the function of alveoli?

• A. Protection of lungs from mechanical shock.
• B. Exchange of respiratory gases.
• C. Storage of respiratory gases.
• D. Prevention of entry of food particles into windpipe.

Answer 1

The correct option is B Exchange of respiratory gases.

$\bullet$ Lungs are made up of many smaller compartments known as alveoli which provide large surface area for the exchange of gases.
$\bullet$ The thin walls of the alveoli contain an extensive network of capillaries.
$\bullet$ Haemoglobin present in the RBCs of the blood absorbs the oxygen from air within alveoli.
$\bullet$ Simultaneously, ${\text{CO}}_2$ and water vapour move out from blood into the alveoli.
$\bullet$ Thus, oxygen is taken into the blood, ${\text{CO}}_2$ and water vapour are removed from the blood and given out by exhalation.