Question

two opposing mechanisms determine alveolar expansion. ___ leads to alveolar expansion, while ___ opposes alveolar expansion.
multiple choice
lung recoil, positive pleural pressure
positive pleural pressure, lung recoil
lung recoil, negative pleural pressure
negative pleural pressure, lung recoil

Explanation:

Negative pleural pressure creates a suction - like force that pulls the alveoli open, leading to alveolar expansion. Lung recoil is the tendency of the lungs to return to their resting, smaller size, thus opposing alveolar expansion.

Answer:

D. negative pleural pressure; lung recoil