What is the primary function of the lungs' alveoli?

The primary function of the lungs' alveoli is to facilitate gas exchange between air and blood. Alveoli are tiny, balloon-like structures located at the end of the bronchioles in the lungs. Their primary role is to allow oxygen from the inhaled air to diffuse into the bloodstream while simultaneously enabling carbon dioxide, a waste product of metabolism, to exit the blood and be exhaled. This gas exchange process is essential for maintaining adequate oxygen levels in the body and removing carbon dioxide, thus supporting cellular respiration and overall metabolic function. The large surface area provided by the numerous alveoli maximizes the efficiency of this exchange process, making it a critical function of the respiratory system.