Which term describes the tiny air sacs that perform gas exchange in the lungs?

The tiny air sacs in the lungs that are responsible for gas exchange are called alveoli. These structures play a crucial role in the respiratory system by allowing oxygen to diffuse into the blood and carbon dioxide to diffuse out of the blood. Alveoli are characterized by their thin walls and are surrounded by capillaries, which facilitate this exchange.

In contrast, the other terms refer to different components of the respiratory system: bronchi are the large passageways that branch from the trachea into the lungs; the trachea is the main airway leading into the lungs; and the larynx functions as a voice box and also helps protect the airway during swallowing. Each of these structures has unique functions that are essential for the overall process of respiration, but it is the alveoli that are specifically designed for the critical process of gas exchange.