What is the role of alveoli in the respiratory system?

The primary role of alveoli in the respiratory system is to facilitate gas exchange. Alveoli are tiny air sacs located at the end of the bronchioles in the lungs and are essential for respiration. Their structure, being highly vascularized and having thin walls, enables oxygen to diffuse from the air within the alveoli into the blood in the surrounding capillaries. At the same time, carbon dioxide diffuses from the blood to the alveoli to be exhaled. This process occurs through passive diffusion, relying on the concentration gradients of the gases.

Alveoli collectively provide a significant surface area for gas exchange, optimized for maximizing the efficiency of oxygen uptake and carbon dioxide removal. The extensive network of capillaries surrounding each alveolus ensures that blood can be readily oxygenated as it passes through the lungs. Thus, the role of alveoli is crucial for maintaining the body's oxygen supply and removing carbon dioxide, making them integral to the respiratory system's function.