Question

Explain how alveoli are adapted for gaseous exchange.

A) Alveoli have a large surface area, thin walls, and a rich blood supply.
B) Alveoli contain high levels of mucus for trapping gases.
C) Alveoli have a thick membrane to prevent gas exchange.
D) Alveoli are filled with water to facilitate gas diffusion.

Answer 1

Alveoli are well-suited for gas exchange due to their large surface area, thin walls for easy diffusion, and close contact with blood capillaries, which enable efficient oxygen and carbon dioxide transfer.

Step-by-step explanation:

The alveoli are adapted for gaseous exchange in a few key ways. They have a large surface area provided by approximately 300 million alveoli per human lung, similar to the size of a tennis court. This surface area is further increased by the elastic walls of the alveoli that stretch during air intake. The walls of the alveoli are thin-walled parenchymal cells, just one cell thick, which enables easy diffusion of gases. Alveoli are also in direct contact with the capillaries, which are themselves one-cell thick, to ensure efficient exchange of oxygen (O₂) and carbon dioxide (CO₂). The intimate contact between alveoli and capillaries facilitate the diffusion of oxygen into the blood and carbon dioxide out of the blood.