What structure in the lungs allows the exchange of gases between the blood and air?

The alveoli are the critical structures in the lungs that facilitate the exchange of gases between the blood and air. These small, balloon-like sacs are surrounded by a network of capillaries and are designed to maximize surface area for gas exchange.

When air enters the lungs, oxygen diffuses from the alveoli into the blood in the capillaries, while carbon dioxide moves from the blood into the alveoli to be exhaled. This process is essential for maintaining the body's oxygen supply and removing carbon dioxide, a metabolic waste product. The extensive surface area of the alveoli, combined with their thin walls, enables efficient diffusion of gases, making them vital for respiratory function.

Other structures like the bronchi and trachea play roles in directing air into the lungs but do not directly participate in the gas exchange process. The larynx is involved in sound production and protects the airway during swallowing. Therefore, while all the listed options are part of the respiratory system, the alveoli are uniquely suited for the gas exchange function.