Lung Capacity And Residual Volume

LUNG CAPACITY
Lung capacities are combinations of specific lung volumes.
The lung capacities are measurements of two or more volumes. The total lung capacity (TLC) is a measurement of the total amount of air that the lung can hold; normally it is 6 litters for adult male and 4.2 litters for an adult female. The vital capacity (VC) measures the maximum amount of air that can be inhaled or exhaled during a respiratory cycle. The Residual Volume (RV) is the amount of gas remaining the lungs after a maximal expiration; normally it takes up 20% of the total lung capacity. VC + RC = TLC. The Inspiratory Reserved Capacity (IRC) is the amount of air that can be inhaled after the end of a normal expiration; normally it takes up 60% of the lung total lung capacity. The Expiratory Reserve Volume (REV) the additional amount of air that can be expired from the lungs by determined effort after normal expiration, normally it is 20% of total lung capacity, TV+IRV+ERV = VC The functional residual capacity (FRC) includes the expiratory reserve volume and the residual volume. The FRC measures the amount of additional air that can be exhaled after a normal exhalation, normally it its 40% of the total lung capacity
The Inspiratory capacity is the amount of air that is inhaled, TV + IRV. It is 60% of the total lung capacity.
The Functional Residual Capacity is the volume in the lungs after residual expiration. This cannot be measured directly by the spirometer because the residual volume (RV) cannot be exhaled, is measured indirectly using helium dilution or nitrogen washout. ERV +