According to Laplace's law, the air pressure necessary to prevent the collapse of an alveolus is directly proportional to the surface tension and inversely proportional to the alveolus's radius. Therefore, as an alveolus gets __________ during __________, there is an increased need for the actions of surfactant to prevent alveolar collapse.

A. larger; expiration
B. larger; inspiration
C. smaller; expiration
D. smaller; inhalation


Answer: C. smaller; expiration

Anatomy & Physiology

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