Which structure is responsible for gas exchange in the lungs?

The alveoli are the small, air-filled sacs located at the end of the bronchioles within the lungs. They are the primary site for gas exchange, where oxygen from the inhaled air diffuses into the blood, and carbon dioxide from the bloodstream is expelled into the air to be exhaled. This process is essential for respiration, as it ensures that oxygen is delivered to the body's tissues while removing carbon dioxide, which is a waste product of metabolism.

The structure of the alveoli is specifically designed to maximize surface area and facilitate this exchange. They have thin walls and are surrounded by a network of capillaries, which further aids in the efficient transfer of gases. The overall efficiency of gas exchange is critical for maintaining proper oxygen levels in the body and supporting cellular function.