What does residual volume refer to?

Residual volume refers to the volume of air that remains in the lungs after a person has exhaled as much as possible. This air is critical because it prevents the lungs from collapsing by ensuring that there is always some air present within the alveoli for gas exchange to occur, even during a forceful exhalation.

Understanding this concept also highlights how the lungs function during different phases of breathing. While other terms may relate to different aspects of lung capacity, such as tidal volume or vital capacity, residual volume is specifically concerned with the air that cannot be voluntarily expelled and plays a significant role in maintaining adequate oxygen levels in the blood. This is particularly important for efficient gas exchange, as it helps ensure that there is a consistent supply of air available for oxygen uptake and carbon dioxide elimination.