What are the structure and functions of alveoli?

Alveoli are tiny balloon-like air sacs present in the lungs where the exchange of oxygen and carbon dioxide takes place during respiration. They provide a large surface area that allows efficient movement of gases between the lungs and blood.

The structure of alveoli is specially adapted for gas exchange. They have very thin, one-cell-thick walls and are surrounded by a network of tiny blood vessels called capillaries. Their moist surface helps gases dissolve and pass easily through the alveolar membrane.

The main function of alveoli is to transfer oxygen from inhaled air into the bloodstream and remove carbon dioxide from the blood into the lungs, which is then exhaled. Millions of alveoli inside the lungs increase the total surface area available for this exchange.

Alveoli play an essential role in the human respiratory system by ensuring that body cells receive oxygen needed for energy production.