What is inspiratory capacity?

• A. The total amount of air forced out of the lungs
• B. The volume of air inhaled after normal expiration
• C. The amount of air in the lungs at rest
• D. The total lung capacity

Answer: (B)

Inspiratory capacity refers to the maximum volume of air that can be inhaled after a normal expiration. It encompasses the tidal volume, which is the amount of air inhaled or exhaled during normal breathing, added to the inspiratory reserve volume, which is the additional air that can be taken in with a forceful effort beyond normal inhalation. This definition is crucial for understanding lung mechanics and respiratory health, particularly in assessing the ability of the lungs to expand and provide sufficient oxygen.

The other options describe different aspects of lung function: the total amount of air forced out of the lungs pertains to vital capacity; the amount of air in the lungs at rest relates to functional residual capacity, which includes residual volume; and total lung capacity includes the entire volume of air the lungs can hold, combining all lung volumes. Therefore, the definition of inspiratory capacity specifically quantifies the inhalation capability following a regular breathing cycle, making it a key measure in respiratory assessments.