What is inspiratory capacity?

• A. The maximum amount of air that can be inhaled after complete expiration.
• B. Largest amount of air that can be forcibly exhaled, normal is 1-1.2 L.
• C. Air at the end of normal respiration.
• D. Sum of all 4 lung volumes.

Answer: (A)

Inspiratory capacity is the amount of air you can inhale starting from the end of a normal expiration. It equals the tidal volume plus the inspiratory reserve volume (IC = TV + IRV) and also can be expressed as TLC minus FRC. This reflects how much you can take in with a deep breath after a typical breath has ended.

The description in the option uses “after complete expiration,” which would start from a much lower lung volume (near residual volume) and does not match the standard starting point for inspiratory capacity. In contrast, inspiratory capacity specifically refers to the maximal inhalation following a normal exhalation.

For contrast:

• The largest amount exhaled after a maximal inhalation is the vital capacity.

• The air at the end of a normal breath is the functional residual capacity.

• The sum of all four lung volumes gives the total lung capacity.