In what way does surfactant contribute to gas exchange?

Surfactant contributes significantly to gas exchange in the lungs primarily by decreasing surface tension in the alveoli. Surfactant is a complex mixture of lipids and proteins produced by the type II alveolar cells. Its presence reduces the surface tension at the air-liquid interface within the alveoli, which is critical for preventing alveolar collapse, especially during exhalation. By lowering surface tension, surfactant increases lung compliance, making it easier for the alveoli to expand during inhalation. This facilitates greater gas exchange efficiency because it allows for more surface area for oxygen and carbon dioxide to diffuse across the alveolar-capillary membrane.

Moreover, decreased surface tension helps maintain the structure of the alveoli, ensuring they remain open and can function effectively in gas exchange. This is particularly important in small alveoli, where the risk of collapse is higher due to their smaller radius. Consequently, surfactant plays a crucial role in optimizing lung function and enhancing overall respiratory efficiency.