What is the role of surfactant in the respiratory system?

• A. To filter pollutants from the air
• B. To reduce surface tension in the alveoli and facilitate gas exchange
• C. To regulate blood pH levels
• D. To stimulate breathing rates

Answer: (B)

Surfactant plays a crucial role in the respiratory system by reducing surface tension in the alveoli, which are the tiny air sacs in the lungs where gas exchange occurs. In a healthy lung, surfactant helps to prevent the alveoli from collapsing, particularly during exhalation when the volume of air is lower. By reducing surface tension, surfactant also ensures that the alveoli can expand more easily during inhalation and optimize the surface area available for oxygen and carbon dioxide exchange.

This function is essential for efficient breathing and effective gas exchange between the air and the bloodstream. Without adequate surfactant, the effort required to inflate the lungs would significantly increase, which can lead to respiratory distress and difficulty in breathing. Conditions such as neonatal respiratory distress syndrome are linked to insufficient surfactant production, highlighting its importance in maintaining healthy lung function.