The diaphragm is the most important muscle of inspiration. The alveolar pressure becomes less than the atmospheric pressure, so air enters the lungs. Expiration a. Want to decrease lung volume, increasing alveolar pressure above atmospheric pressure. Decreasing thoracic volume decreases lung volume. E. Changes in Resistance of Airways 1.
Air flow is determined by both pressure difference and amount of resistance in the airway.
Amount of resistance determined primarily by the radius of the airway. Lung Volumes and Capacities A. Pulmonary Volumes 1. B. Pulmonary Capacities 1. Sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume. Sum of all lung volumes.