Small air sacs comprising the innermost structure of the lungs. It is through the delicate walls of the alveoli that gas exchange occurs between the blood (flowing through the pulmonary capillaries) and the inhaled or exhaled air.
The millions of tiny air sacs in the lungs at the ends of bronchioles where oxygen is exchanged for carbon dioxide from the blood. In CF, mucus clogs alveoli, and interferes with oxygen-carbon dioxide exchange.
The tiny sac-like air spaces in lung where carbon dioxide and oxygen are exchanged.