What is the total lung capacity equal to?

Total lung capacity (TLC) is the maximum amount of air that the lungs can hold. It is composed of several lung volumes: vital capacity (VC), which is the maximum amount of air a person can exhale after taking the deepest breath possible, and residual volume (RV), the amount of air that remains in the lungs after a maximal exhalation. The correct answer states that total lung capacity is equal to the vital capacity plus the residual volume.

This relationship is derived from the understanding that TLC is the sum of the air that can be forcibly exhaled (vital capacity) and the air that cannot be exhaled (residual volume), ensuring that the lungs remain inflated even after full exhalation. Thus, if you were to measure the TLC of an individual, it would equal the volume of air that they can breathe in and out (vital capacity) plus the air that stays in the lungs after breathing out (residual volume).

In other options, combinations such as inspiratory reserve volume or dead space volume do not directly contribute to the calculation of total lung capacity, as they either represent air that can be inhaled but is not part of total lung capacity or represent air that does not participate in gas exchange,