What effect does surfactant have on surface tension in the alveoli?

What effect does surfactant have on surface tension in the alveoli?

• A. Increases
• B. Decreases
• C. Has no effect
• D. Varies with lung volume

Answer: (B)

Surfactant is a complex mixture of lipids and proteins secreted by the type II alveolar cells in the lungs. Its primary role is to reduce surface tension at the air-liquid interface within the alveoli. When surfactant is present, it spreads out along the surface of the alveolar fluid, disrupting the cohesive forces between water molecules. This disruption decreases the surface tension, which is crucial for preventing the collapse of alveoli during expiration and for improving lung compliance. By reducing surface tension, surfactant allows for more efficient gas exchange and helps to stabilize the alveoli, maintaining their shape and preventing atelectasis (collapse of the alveoli). This action is essential for normal respiratory function, particularly in newborns, where a lack of enough surfactant can lead to conditions such as neonatal respiratory distress syndrome. Overall, the ability of surfactant to decrease surface tension is vital for optimal pulmonary mechanics and gas exchange.

Surfactant is a complex mixture of lipids and proteins secreted by the type II alveolar cells in the lungs. Its primary role is to reduce surface tension at the air-liquid interface within the alveoli. When surfactant is present, it spreads out along the surface of the alveolar fluid, disrupting the cohesive forces between water molecules. This disruption decreases the surface tension, which is crucial for preventing the collapse of alveoli during expiration and for improving lung compliance.

By reducing surface tension, surfactant allows for more efficient gas exchange and helps to stabilize the alveoli, maintaining their shape and preventing atelectasis (collapse of the alveoli). This action is essential for normal respiratory function, particularly in newborns, where a lack of enough surfactant can lead to conditions such as neonatal respiratory distress syndrome. Overall, the ability of surfactant to decrease surface tension is vital for optimal pulmonary mechanics and gas exchange.