According to the Law of Laplace (P = 2T / r), what would happen to smaller alveoli compared to larger ones if surfactant were completely absent? (Hard)
Answer and explanation
Correct answer: D. Smaller alveoli would generate higher collapse pressure and empty into larger alveoli
- Step 1: By Laplace law, collapsing pressure P is inversely proportional to radius r if surface tension T is constant. Step 2. Without surfactant, smaller alveoli (smaller r) would have higher internal pressure and collapse, emptying their air into larger alveoli (atelectasis). Answer: Smaller alveoli would generate higher collapse pressure and empty into larger alveoli. Why not the others: Smaller alveoli cannot expand faster without lower surface tension; identical pressure requires variable surface tension provided by surfactant; blood is retained in capillaries.
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