What is one primary function of surfactant in the lungs?

• A. Increase lung elasticity
• B. Prevent alveolar collapse
• C. Enhance oxygen diffusion
• D. Facilitate carbon dioxide excretion

Answer: (B)

Surfactant plays a crucial role in maintaining the integrity and function of the alveoli, the tiny air sacs in the lungs where gas exchange occurs. One of its primary functions is to reduce surface tension in the alveolar fluid. By doing so, surfactant prevents alveolar collapse, particularly during expiration when the lung volume decreases. This is essential because if the alveoli were to collapse, it would require significant effort to reopen them, which could lead to impaired gas exchange and reduced lung compliance.

The presence of surfactant allows the alveoli to remain stable at various lung volumes, promoting efficient ventilation and ensuring that the lungs can expand and contract without resistance. This stability is vital for maintaining optimal surface area for gas exchange, ultimately supporting effective pulmonary function.

While surfactant contributes to other processes, such as helping to maintain lung elasticity and potentially influencing diffusion rates, its primary and most critical function is to prevent the collapse of the alveoli, thus protecting them from atelectasis and maximizing gas exchange efficiency.