Question

Following an optimal inspiration, the amount of air that can be forced from the lungs in a single exhalation is called the:

1) functional reserve capacity.
2) expiratory reserve volume.
3) residual expiratory volume.
4) fraction of inspired oxygen.

Answer 1

The expiratory reserve volume (ERV) refers to the additional air that can be exhaled forcefully after a normal exhalation. It is not to be confused with the functional residual capacity (FRC) or the total lung capacity (TLC), which include this volume, among others.

Step-by-step explanation:

The amount of air that can be forced from the lungs in a single exhalation after an optimal inspiration is called the expiratory reserve volume (ERV). The ERV represents the additional air that can be exhaled forcefully after completing a normal, quiet respiratory cycle. On the other hand, the functional residual capacity (FRC) consists of the expiratory reserve volume plus the residual volume, which is the air remaining in the lungs after a maximal exhalation. The total lung capacity (TLC) is the sum of all lung volumes, including the residual volume (RV), ERV, tidal volume (TV), and inspiratory reserve volume (IRV).