Where does the actual exchange of gases with blood occur in the pulmonary system?

The exchange of gases with blood occurs in the alveoli, which are tiny air sacs located within the lungs. The alveoli are specifically structured to facilitate gas exchange due to their large surface area, thin walls, and close proximity to the capillaries. When air enters the lungs, oxygen diffuses from the alveoli into the blood in the capillaries, while carbon dioxide diffuses from the blood into the alveoli to be exhaled. This efficient exchange is crucial for maintaining proper oxygen levels in the blood and removing carbon dioxide, a waste product of metabolism.

In contrast, the bronchi and trachea serve primarily as passageways for air to move into and out of the lungs, and they do not participate directly in the gas exchange process. The term "lungs" refers to the entire organ but does not specify the site of gas exchange, which is confined to the alveoli.