State the volume of air remaining in lungs after a normal breathing.
The volume of air remaining in the lungs after a normal expiration is known as functional residual capacity (FRC).
It includes expiratory reserve volume (ERV) and residual volume (RV). It is calculated by the formula -: FRC = ERV + RV.
ERV is the maximum volume of air that can be exhaled after a normal expiration. It is about 1000 mL to 1100 mL.
RV is the volume of air remaining in the lungs after maximum expiration. It is about 1100 mL to 1200 mL.
FRC = ERV + RV
FRC = 1100 + 1200
FRC = 2300 mL
Functional residual capacity of the human lungs is about 2.1 - 2.3 L.