Alveolar cell

Alveolar cells are the cells found in the alveoli, the tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide occurs. There are two types of alveolar cells, known as type I and type II.

Type I Alveolar Cells[edit | edit source]

Type I alveolar cells are the most common type of cells in the alveoli, making up about 95% of the alveolar surface area. These cells are extremely thin, which allows for the rapid exchange of gases between the lungs and the bloodstream. Type I alveolar cells are also involved in the process of gas exchange.

Type II Alveolar Cells[edit | edit source]

Type II alveolar cells, also known as great alveolar cells, are less common but have several important functions. They produce and secrete surfactant, a substance that reduces the surface tension of the fluid lining the alveoli, preventing the alveoli from collapsing. Type II alveolar cells can also divide and differentiate into type I cells, helping to repair the alveolar epithelium after injury.

Function[edit | edit source]

The primary function of alveolar cells is to facilitate the exchange of gases between the lungs and the bloodstream. Oxygen from the air we breathe diffuses across the thin walls of the alveoli and into the blood, while carbon dioxide diffuses from the blood into the alveoli, from where it can be exhaled.

Pathology[edit | edit source]

Damage to the alveolar cells can lead to several lung diseases, including pneumonia, emphysema, and acute respiratory distress syndrome (ARDS). In these conditions, the normal gas exchange function of the alveoli is impaired, leading to symptoms such as shortness of breath and low oxygen levels in the blood.