What are the different pulmonary and respiratory capacities

When two or more of the respiratory volumes are considered together, pulmonary capacities are obtained which can be used in clinical diagnosis.

(i) Inspiratory Capacity (IC)

- The total volume of air a person can inspire after a normal expiration is called Inspiratory Capacity (IC).

- It is the sum total of tidal volume and inspiratory reserve volume, i.e.

IC = TV + IRV

(ii) Expiratory Capacity (EC)

- The total volume of air a person can expire after a normal inspiration is called Expiratory Capacity (EC).

- It is the sum total of tidal volume and expiratory reserve volume, i.e.

EC = TV + ERV

(iii) Functional Residual Capacity (FRC)

- The volume of air that will remain in the lungs after a normal expiration is called

as Functional Residual Capacity (FRC).

- It includes the residual volume and expiratory reserve volume, i.e.

FRC = RV + ERV

(iv) Vital Capacity (VC)

- The maximum volume of air a person can breathe in after a forced expiration is

called as Vital Capacity (VC).

- It is the sum total of tidal volume, inspiratory reserve volume and expiratory

reserve volume, i.e. VC = TV + IRV + ERV

(v) Total Lung Capacity

- The total volume of air accommodated in the lungs at the end of a forced

inspiration is called Total Lung Capacity.

- It is the sum total of tidal volume, inspiratory reserve volume, expiratory reserve

volume and residual volume, i.e. TLC = TV + IRV + ERV + RV or VC + RV