What is the primary role of the alveoli in the respiratory system?

The primary role of the alveoli in the respiratory system is indeed gas exchange. Alveoli are tiny air sacs located at the ends of the bronchioles in the lungs, where the actual exchange of oxygen and carbon dioxide takes place. They provide a large surface area and a thin barrier that allows oxygen from the air to diffuse into the bloodstream while simultaneously allowing carbon dioxide, which is a waste product of metabolism, to diffuse out of the blood and into the alveoli, where it can be exhaled.

This process of gas exchange is vital for maintaining the body’s oxygen levels and removing carbon dioxide, thus supporting cellular respiration and overall metabolic functions. The structure of the alveoli—being highly vascularized and surrounded by a network of capillaries—facilitates this efficient exchange, making them essential for respiration. Other roles listed in the options, such as sound production, oxygen transport, or carbon dioxide storage, are not functions of the alveoli but involve different components of the respiratory or circulatory systems.