Why is pulmonary surfactant such an important biologic substance?

a. It clears out cellular debris.
b. It is an alveolar macrophage.
c. It promotes lung contraction aiding exha-lation.
d. It promotes lung stability.

ANS: D
Surfactant functions to reduce the surface tension of the alveolus, which results in shedding wa-ter from the alveolar surface; helps to prevent alveolar surface tension-driven collapse; improves lung compliance; and reduces the work of breathing.