Which term refers to the remaining air in the lungs that is not exhaled during a forced expiration?

The term that refers to the remaining air in the lungs that is not exhaled during a forced expiration is known as residual volume. This volume represents a critical aspect of lung function, as it ensures that there is always a supply of air in the lungs to prevent alveolar collapse and to facilitate gas exchange. Residual volume plays a vital role in maintaining adequate oxygenation of the blood and helps keep the lungs inflated, providing a reserve of air that is crucial, especially during periods of increased respiratory demand.

In contrast, expiratory reserve volume measures the amount of additional air that can be forcibly exhaled after a normal expiration, and inspiratory reserve volume measures the amount of air that can be forcibly inhaled after a normal tidal inhalation. Tidal volume refers to the amount of air that is inhaled or exhaled during normal breathing. Each of these other terms describes different components and phases of breathing but does not capture the concept of the air volume that remains in the lungs after a complete exhalation.