Question

How are lungs designed in human beings to maximize the area of exchange of gases?

• A. Presence of huge number of alveoli
• B. Presence of huge number of alveoli which possess a network of capillaries over their surface
• C. Presence of huge number of alveoli which possess a network of capillaries over their surface, functioning as respiratory surface
• D. None of these

Answer 1

The correct option is C Presence of huge number of alveoli which possess a network of capillaries over their surface, functioning as respiratory surface

• Each lungs has highly branched respiratory tract called respiratory tree. A primary bronchus divides into secondary bronchi, secondary into segmental bronchi, segmental bronchus into bronchioles which divides into terminal bronchioles, respiratory bronchioles, alveolar sacs and alveoli.
• Alveoli are small rounded pouches which are extremely thin walled and possess a network of capillaries over their surface. They function as respiratory surfaces.
• The total area of all the alveoli is more than $80m^2$. It is several times more than the surface of the whole human body.
• Thus, the human lungs are designed to maximise the area of exchange of gases.

Therefore, the correct answer is option C.