What is the primary function of the alveoli in the lungs?

The primary function of the alveoli in the lungs is to facilitate gas exchange between air and blood. Alveoli are tiny, balloon-like structures at the end of the respiratory tree where oxygen and carbon dioxide are exchanged. They provide a large surface area due to their numerous and thin-walled nature, which enhances the efficiency of gas exchange. This process occurs through diffusion, allowing oxygen from the inhaled air to move into the bloodstream, where it is carried to tissues, while carbon dioxide from the blood is transferred to the alveoli to be exhaled.

This essential function makes alveoli critical for respiration and overall metabolic processes, ensuring that the body's tissues receive the oxygen needed for cellular activity while simultaneously removing carbon dioxide, a waste product of metabolism.