ATI Pathophysiology Practice Exam

What is the function of surfactant in the alveoli of the lungs?

1. Increase lung volume

2. Moisten incoming air

3. Prevention of alveoli collapse

4. Facilitation of gas exchange

The correct answer is: Prevention of alveoli collapse

Surfactant plays a critical role in maintaining alveolar stability and proper lung function. Its primary function is to reduce surface tension within the alveoli. This reduction in surface tension is essential because the alveoli, which are tiny air sacs in the lungs, are lined with a thin film of fluid. Without surfactant, the high surface tension would cause these air sacs to collapse, especially during exhalation when lung volume decreases. By preventing the collapse of the alveoli, surfactant ensures that they remain open and available for gas exchange. This is vital for efficient oxygen uptake and carbon dioxide removal, which are essential components of respiration. Therefore, the presence of surfactant allows for more uniform expansion and contraction of the alveoli during breathing, contributing to overall respiratory efficiency and gas exchange. The other functions listed, while related to the respiratory system, do not capture the specific and primary role of surfactant. For instance, surfactant does not primarily work to increase lung volume, moisten incoming air, or directly facilitate gas exchange; rather, it creates an environment in which gas exchange can occur more effectively by maintaining alveolar structure.