alvéolen

Alveoli are tiny, balloon-like air sacs found in the lungs. They are the primary sites of gas exchange in the respiratory system, where oxygen from inhaled air passes into the bloodstream and carbon dioxide from the blood is transferred to the air to be exhaled. Each lung contains millions of alveoli, which collectively provide a vast surface area for this crucial process.

The walls of the alveoli are extremely thin, typically only one cell thick, which facilitates rapid diffusion of gases. They are also surrounded by a dense network of capillaries, the smallest blood vessels in the body, further optimizing gas exchange. A thin layer of moisture lines the inner surface of each alveolus, which allows oxygen to dissolve before it can cross the alveolar membrane. This moisture is covered by a specialized substance called surfactant, which reduces surface tension and prevents the alveoli from collapsing during exhalation.

The structure of alveoli is highly adapted for their function. Their small size and large number maximize the surface area available for gas exchange, an essential feature for meeting the body's oxygen demands. The close proximity of the alveoli to the capillaries ensures that oxygenated blood is efficiently distributed throughout the body and that carbon dioxide is effectively removed. Any damage or inflammation to the alveoli, such as in conditions like pneumonia or emphysema, can significantly impair lung function and gas exchange.