What is the function of surfactant in the lungs?

What is the function of surfactant in the lungs?

• A. To aid in the exchange of oxygen and carbon dioxide
• B. To maintain surface tension of alveoli
• C. To prevent infections in the respiratory tract
• D. To facilitate the movement of air in and out of the lungs

Answer: (B)

Surfactant is a critical substance produced by the type II alveolar cells in the lungs. Its primary function is to reduce surface tension within the alveoli, the tiny air sacs where gas exchange occurs. By lowering surface tension, surfactant helps to prevent the alveoli from collapsing, especially during exhalation when the lungs are at their smallest volume. This property is vital as it allows the alveoli to remain open and function effectively, ensuring that a sufficient surface area is available for the exchange of oxygen and carbon dioxide. Additionally, by stabilizing alveoli of various sizes, surfactant contributes to optimal lung compliance and efficiency during breathing.

While other options may relate to lung function, they do not specifically pertain to the role of surfactant. For instance, while surfactant plays an indirect role in facilitating gas exchange by promoting alveolar stability, it does not directly increase the rate of gas exchange itself. Similarly, preventing infections is primarily the role of mucus and immune mechanisms in the respiratory tract, not surfactant. Lastly, although surfactant plays a role in making breathing easier, its main function is not to facilitate air movement per se, but rather to ensure alveolar stability for effective respiration.