Final answer:
After a forceful exhalation, the air that remains in the lungs is referred to as the residual volume. This air cannot be expelled from the lungs and is essential for preventing lung collapse and ensuring a continuous exchange of respiratory gases.
Step-by-step explanation:
After a forceful exhalation, the air that remains in the lungs is the residual volume (RV). Residual volume is the amount of air left in the lungs after a maximal exhale, and it cannot be expelled. The lungs always contain this air to prevent lung collapse and maintain consistent concentrations of respiratory gases.
Lung volumes are divided into four categories: tidal volume (TV), expiratory reserve volume (ERV), inspiratory reserve volume (IRV), and residual volume (RV). The residual volume is significant because it ensures that there is a continual exchange of oxygen and carbon dioxide, preventing large fluctuations in respiratory gases. It is also key to the lung's ability to function properly as the lungs are never completely empty, even after a forceful exhalation.
The maximum amount of air that can be moved in or out of the lungs in a single respiratory cycle is referred to as the total lung capacity. This includes the sum of tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume.