What is the role of alveoli in the lungs?

The primary role of alveoli in the lungs is to allow gas exchange. These tiny, balloon-like structures are where oxygen from the air is taken into the bloodstream, and carbon dioxide, a waste product of metabolism, is expelled from the blood into the air to be exhaled. Alveoli provide a vast surface area due to their numerous and small structure, maximizing the efficiency of this gas exchange process. This exchange is crucial for maintaining the body’s oxygen levels and removing carbon dioxide, thereby supporting cellular respiration and overall metabolic function.

Alveoli are specifically adapted for this function with thin walls (one cell thick), which facilitate the diffusion of gases, and they are surrounded by a rich network of capillaries to transport the gases to and from the lungs. In contrast, other options like storing air, producing mucus, or filtering pollutants describe functions associated with different structures in the respiratory system, but do not accurately characterize the specialized role of alveoli.