What is the primary function of Type II alveolar cells?

Type II alveolar cells, also known as type II pneumocytes, play a crucial role in the respiratory system, particularly within the alveoli—the tiny air sacs in the lungs where gas exchange occurs. The primary function of these cells is the secretion of pulmonary surfactant, a substance composed mainly of lipids and proteins.

Pulmonary surfactant serves several essential functions. It reduces surface tension within the alveoli, preventing the collapse of these air sacs during exhalation. This is critical for maintaining proper lung function and ensuring effective gas exchange; without sufficient surfactant, the effort required to inflate the alveoli increases significantly, which can lead to respiratory complications.

While gas exchange occurs primarily through the type I alveolar cells, which are flat and facilitate this process, type II alveolar cells are specialized for surfactant production. The formation of the alveolar wall involves a different set of cells and structures, and the production of mucus is mainly associated with other epithelial cells in the respiratory tract, particularly in the conducting airways. Thus, the role of Type II alveolar cells is uniquely tied to surfactant production and maintenance of alveolar stability.