pneumosyytit

Pneumocytes are the primary cells that line the alveoli of the lungs. They are crucial for the exchange of gases, specifically oxygen and carbon dioxide, between the air in the lungs and the blood. There are two main types of pneumocytes: type I and type II.

Type I pneumocytes are squamous, thin cells that cover about 95% of the alveolar surface area. Their primary function is to facilitate gas exchange due to their extremely thin structure, allowing for rapid diffusion. They are highly specialized for this role and are not capable of cell division. Damage to type I pneumocytes can impair gas exchange.

Type II pneumocytes, also known as great alveolar cells, are cuboidal cells that are interspersed among type I pneumocytes. They are fewer in number but are vital for lung repair and function. Type II pneumocytes are responsible for producing and secreting pulmonary surfactant, a substance that reduces surface tension within the alveoli. This reduction in surface tension prevents the alveoli from collapsing, especially during exhalation, and aids in lung compliance. Type II pneumocytes can also differentiate into type I pneumocytes, playing a key role in the regeneration of the alveolar epithelium after injury.