Which of the following best describes what occurs in the alveoll or the human lungs?

Question:- Which of the following best describes what occurs in the alveoll or the human lungs?

a.      carbon dioxide gas is exchanged into the surrounding capillaries whereas oxygen gas is exchanged into the lungs

b.      both carbon dioxide and oxygen gas are exchanged into the lungs and neither are exchanged into the surrounding capillaries

c.      oxygen gas is exchanged into the surrounding capillaries whereas carbon dioxide gas is exchanged into the lungs

d.      both carbon dioxide and oxygen gas are exchanged into the surrounding capillaries and neither are exchanged into the lungs

Answer: c. oxygen gas is exchanged into the surrounding capillaries whereas carbon dioxide gas is exchanged into the lungs

The alveoli are small air sacs found in the lungs where gas exchange between the lung and blood takes place. In particular, oxygen diffuses from the alveoli into capillaries around the walls of these spaces and carbon dioxide moves in opposite direction.

The oxygen enters the bloodstream through the alveoli where it diffuses from inhaled air. Oxygen concentration in the capillaries is lower than that of alveoli, therefore oxygen passively diffuses down its gradient into the capillaries. During this time, carbon dioxide moves from the capillaries to alveoli. Carbon dioxide has higher concentration in the capillaries, this due to their production by cells as a waste metabolism. Carbon dioxide moves down its concentration gradient from the blood to air in alveoli.

As a result of countercurrent exchange oxygenation and elimination of waste carbon dioxide, due to this. The alveoli serve as the area of contact for gas exchange between blood and lungs . Choice C correctly describes that oxygen travels from alveoli to capillaries while carbon dioxide does the opposite.