Question

which of the following factors keeps the alveoli expanded?
multiple choice
a pneumothorax
negative intra - alveolar pressure
negative pleural pressure
alveolar pressure being equal to atmospheric pressure
a reduction in surfactant

Explanation:

Negative pleural pressure creates a suction - like force that opposes the natural tendency of the alveoli to collapse. A pneumothorax causes alveolar collapse. Negative intra - alveolar pressure is involved in air flow but not in keeping alveoli expanded. When alveolar and atmospheric pressures are equal, there is no net force for expansion. A reduction in surfactant increases surface tension and promotes alveolar collapse.

Answer:

C. Negative pleural pressure