What is the name for the air that remains in the lungs after a complete exhalation?

The correct term for the air that remains in the lungs after a complete exhalation is Residual Volume. This volume is crucial because it ensures that there is always air in the lungs, which helps keep the alveoli open and facilitates gas exchange even when the body is at rest or during extensive physical activity. The presence of residual volume prevents lung collapse and ensures a more constant supply of oxygen to the bloodstream.

In contrast, Inspiratory Reserve Volume refers to the additional air that can be inhaled after a normal inhalation, representing the lung's capacity for increased oxygen intake. Vital Capacity denotes the maximum amount of air that can be exhaled after maximal inhalation and encompasses the sum of several lung volumes, including tidal volume, inspiratory reserve volume, and expiratory reserve volume. Expiratory Reserve Volume is the additional air that can be forcibly exhaled after completing a normal exhalation, but it does not account for the air that remains in the lungs afterward. Thus, Residual Volume specifically addresses the air that stays in the lungs after a full breath out.