Lung Volumes and Capacities
Lung volumes and capacities refer to the changes in lung volume during inspiration and expiration and the absolute volume of air that the lungs hold during the respiratory cycle.
These relationships are recorded using a device called a spirometer.
1) Tidal Volume (TV)
The amount of air that moves in and out of the lungs during inspiration and expiration with quiet breathing.
2) Inspiratory Reserve Volume (IRV)
The air inspired with maximal inspiratory effort in excess of the tidal volume.
3) Expiratory Reserve Volume (ERV)
The additional air that can be forcibly exhaled after the expiration of a normal tidal volume.
4) Residual Volume (RV)
The volume of air remaining in the lungs after maximal exhalation.