Alveoli are primarily responsible for which function?

Alveoli are tiny air sacs located in the lungs, and their primary function is facilitating gas exchange. They are the site where oxygen from the inhaled air passes through the alveolar walls into the surrounding capillaries to enter the bloodstream, while carbon dioxide is expelled from the blood into the alveoli to be exhaled. This gas exchange process is vital for respiration, as it provides oxygen to the body’s cells and removes carbon dioxide, a waste product of metabolism.

This function distinguishes alveoli from other structures and processes in the body. Transporting nutrients is a role of the digestive system and circulatory system, while connecting blood vessels relates to the vascular system's structural integrity. Pumping blood is the function of the heart, which circulates blood throughout the body. Hence, the unique role of alveoli in gas exchange is crucial to respiratory physiology and overall health.