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 air sacs located at the end of the respiratory tree, and they provide a large surface area for oxygen and carbon dioxide to be exchanged between the air and the bloodstream. Each alveolus is surrounded by a network of capillaries, allowing oxygen to diffuse from the air inside the alveoli into the blood, while carbon dioxide from the blood moves into the alveoli to be exhaled. This process is essential for respiration and maintaining the body's oxygen levels, making alveoli critical components of the respiratory system.

While filtering dust, protecting against infections, and supporting lung structure are important functions of the respiratory system, they are not the primary roles of the alveoli themselves. The main reason for the presence of alveoli is their specialized structure that optimizes gas exchange efficiency.