What physiological function is increased due to the presence of surfactant in the alveoli?

Surfactant is a substance composed of lipids and proteins that is secreted by type II alveolar cells in the lungs. Its primary role is to reduce surface tension at the air-liquid interface within the alveoli. By lowering surface tension, surfactant plays a crucial role in increasing lung compliance, which refers to the ability of the lungs to stretch and expand during inhalation.

When surfactant is present, it stabilizes the alveoli and prevents them from collapsing, thereby allowing them to open more easily during breathing. This results in a reduction of the work required for lung expansion and improves the overall efficiency of the respiratory system. Increased lung compliance is vital for effective ventilation, as it allows for normal lung function even at lower pressures during inspiration.

While surfactant has indirect effects on other aspects of pulmonary physiology, such as facilitating gas exchange by maintaining alveolar stability, its primary and most significant function is enhancing lung compliance. Therefore, the presence of surfactant directly contributes to improved lung function by allowing the lungs to expand more easily with each breath.