During quiet inspiration
A) The lung expands from elastic forces
B) The intrapleural pressure is positive
C) Alveolar pressure is less than atmospheric pressure
D) The lung volume is less than the FRC
E) Surfactant is concentrated more

Question

Quizplus · Accepted Answer

During quiet inspiration, alveolar pressure decreases below atmospheric pressure, allowing air to flow into the lungs. This is due to the expansion of the chest cavity and lungs, driven by the contraction of the diaphragm and external intercostal muscles, not by elastic forces or a positive intrapleural pressure. The lung volume increases, often exceeding the functional residual capacity (FRC), and surfactant concentration changes are more related to lung volume changes and alveolar surface area adjustments rather than being directly caused by the act of inspiration.

During Quiet Inspiration