What is the primary function of surfactant in the lungs?

Surfactant plays a crucial role in respiratory physiology, particularly in the function of the alveoli, which are the tiny air sacs in the lungs where gas exchange occurs. The primary function of surfactant is to reduce surface tension within the alveoli. By doing this, surfactant prevents the alveoli from collapsing during exhalation, thereby ensuring that they remain open and ready for gas exchange during the next inhalation. This stabilization of the alveoli is vital for maintaining proper respiratory function, as it contributes to the efficient exchange of oxygen and carbon dioxide.

In addition to preventing collapse, surfactant also aids in keeping the alveoli inflated at lower lung volumes and ensures uniform expansion of the lungs during breathing. This function is particularly important at the end of expiration, when the alveoli are at their smallest and are most prone to collapsing due to the high surface tension of the fluid lining them.

While surfactant does indeed have a role in enhancing gas exchange indirectly by keeping alveoli open and improving lung compliance, its primary and most critical function is to prevent alveolar collapse. This process helps to maintain optimal lung function and prevents complications such as atelectasis (lung collapse) that can arise when alveoli do not remain properly inflated