ABSTRACT
The elastic properties of the lung and chest wall and air flow resistance are related to breathing mechanics. Figure 23.1 shows the lung volumes used in respi ratory physiology. Vital capacity is the maximum volume that can be expired after a maximal inspiration. Total lung capacity is the volume of the lungs after a maxi mal inspiration. Residual volume is that volume remaining in the lungs after a maximal expiration. This is about 25% of the total lung capacity. Functional re sidual volume is the volume in the lungs at the end of a normal expiration. Tidal volume is the volume of a spontaneous breath. These are the major volumes; the inspiratory capacity, expiratory reserve volume, and inspiratory reserve volume are less commonly used terms.
