Anatomy and Physiology II Practice Test

Which term is used to describe the volume of air that remains in the lungs after exhalation?

1. vital capacity

2. tidal volume

3. residual volume

4. total lung capacity

The correct answer is: residual volume

Residual volume refers to the amount of air that remains in the lungs after a person has exhaled as much air as possible. This volume is important because it prevents the alveoli from collapsing and allows for continuous gas exchange even during the phases of breathing where no air enters the lungs. Understanding this concept is crucial because residual volume contributes to the overall functioning of the respiratory system. It enables the lungs to maintain a certain level of inflation and ensures that oxygen remains available for gas exchange, even during extended periods of exhalation. The other terms relate to different aspects of lung capacity: vital capacity encompasses the maximum amount of air that can be exhaled after taking the deepest breath possible, tidal volume refers to the volume of air inhaled or exhaled during normal breathing, and total lung capacity is the sum of all lung volumes, including the residual volume. Each of these plays a distinct role in respiratory physiology, but residual volume specifically highlights the air that lingers in the lungs post-exhalation.