Multiple choice

What is the mechanism of action of surfactant?

  1. It breaks the structure of water in the alveoli.

  2. It lubricates the flow of CO2 diffusion.

  3. It makes the capillary surface hydrophilic.

  4. None of these

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A Correct answer
Explanation

Surfactant reduces surface tension by disrupting the cohesive forces of water molecules at the air-liquid interface in alveoli. This prevents alveolar collapse during expiration. It does not lubricate gas flow or alter capillary surface properties - its primary function is breaking the water structure that would otherwise cause alveolar instability.

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