What is the role of great alveolar cells (Type II) in the alveoli?

Great alveolar cells, also known as Type II alveolar cells, play a crucial role in the respiratory system primarily through the secretion of pulmonary surfactant. Surfactant is a complex mixture of lipids and proteins that reduces surface tension within the alveoli, the tiny air sacs in the lungs where gas exchange occurs. By lowering surface tension, surfactant prevents the alveoli from collapsing, especially during exhalation, thus maintaining proper lung function and facilitating optimal gas exchange.

In addition to surfactant production, Type II cells also have a role in the repair and regeneration of the alveolar epithelium, but their most significant contribution relates to surfactant, which is essential for normal respiratory mechanics and reducing the work of breathing. This function is critical as it directly influences the ability of the lungs to expand easily and efficiently fill with air.