What is the primary function of alveoli in the lungs?

The primary function of alveoli in the lungs is to facilitate gas exchange. Alveoli are tiny, balloon-like structures located at the end of the bronchioles in the lungs, and they play a crucial role in respiration. The walls of alveoli are extremely thin and are surrounded by a network of capillaries, which allows for the efficient transfer of gases.

When air reaches the alveoli, oxygen diffuses from the air inside the alveoli into the blood in the capillaries. At the same time, carbon dioxide, which is a waste product produced by the body's cells, diffuses from the blood into the alveoli to be exhaled. This process is vital for maintaining the body's oxygen levels and removing carbon dioxide, making the alveoli integral to effective breathing and overall respiratory function.

Understanding the primary function of alveoli helps highlight their importance in the respiratory system, as the other options do not specifically pertain to their role in gas exchange or the mechanics of breathing.