ANATOMY

Detailed explanation-1: -It is calculated by summing tidal volume, inspiratory reserve volume, and expiratory reserve volume.

Detailed explanation-2: -The residual volume (RV) is the volume of gas remaining in the lung at the end of a full expiration. It is calculated by subtracting the expiratory reserve volume from the functional residual capacity: RV = FRC−ERV, or RV = TLC−IVC.

Detailed explanation-3: -The functional residual capacity (FRC) includes the expiratory reserve volume and the residual volume. The FRC measures the amount of additional air that can be exhaled after a normal exhalation. The total lung capacity (TLC) is a measurement of the total amount of air that the lung can hold.

Detailed explanation-4: -Four standard lung volumes, namely, tidal (TV), inspiratory reserve (IRV), expiratory reserve (ERV), and residual volumes (RV) are described in the literature. Alternatively, the standard lung capacities are inspiratory (IC), functional residual (FRC), vital (VC) and total lung capacities (TLC).

Detailed explanation-5: -The residual volume functions to maintain the patency of alveoli even after maximal forced expiration. In healthy lungs, the air that makes up the residual volume is utilized for continual gas exchange between breaths.