Distinguish between
(a) IRV and ERV
(b) Inspiratory capacity and Expiratory capacity
(c) Vital capacity and Total lung capacity

Inspiratory reserve volume (IRV)

Expiratory reserve volume (ERV)

1. It is the maximum volume of air that can be inhaled after a normal inspiration.

2. It is about 2500 – 3500 mL in the human lungs.

1. It is the maximum volume of air that can be exhaled after a normal expiration.

2. It is about 1000 – 1500 mL in the human lungs.

Inspiratory capacity (IC)

Expiratory capacity (EC)

1. It is the volume of air that can be inhaled after a normal expiration.

2. It includes tidal volume and inspiratory reserve volume.

IC = TV + IRV

1. It is the volume of air that can be exhaled after a normal inspiration.

2. It includes tidal volume and expiratory reserve volume. 
 

EC = TV + ERV

Vital capacity (VC)

Total lung capacity (TLC)

1. It is the maximum volume of air that can be exhaled after a maximum inspiration. It includes IC and ERV.

2. It is about 4000 mL in the human lungs.

1. It is the volume of air in the lungs after maximum inspiration. It includes IC, ERV, and residual volume.

2. It is about 5000 – 6000 mL in the human lungs.