Which lung volume represents air that cannot be expelled from the lungs?

Residual Volume is the specific lung volume that represents the air remaining in the lungs after a forced exhalation. This volume cannot be expelled from the lungs, even with maximal effort, and it is crucial for maintaining a continuous exchange of gases in the alveoli. It prevents complete collapse of the lungs and ensures that there is always enough air for gas exchange, contributing to overall lung function.

In contrast, Inspiratory Reserve Volume refers to the additional air that can be inhaled after a normal inhalation, Tidal Volume represents the amount of air moved in and out of the lungs during normal breathing, and Vital Capacity is the total volume of air that can be exhaled after a maximal inhalation, which does not account for the air that remains in the lungs. Understanding these volumes provides insight into respiratory physiology and is essential for effective patient management, especially in critical care and ventilation scenarios.