What is vital capacity (VC)?

What is vital capacity (VC)?

• A. The maximal inspiratory volume after a normal inspiration.
• B. The volume of air remaining after a maximal expiration.
• C. The maximal volume of air that can be expired following a maximal inspiration.
• D. The volume expired in the first second of a maximal expiration.

Answer: (C)

Vital capacity is the maximum amount of air you can exhale after taking the deepest possible breath. It reflects how much usable air can be moved in one forceful breath and equals the sum of inspiratory reserve volume (air you can inhale beyond a normal breath), tidal volume (the normal breath you take), and expiratory reserve volume (air you can exhale beyond a normal breath). In other words, after a maximal inspiration, the total volume you can expel is the vital capacity. It does not include residual volume, which stays in the lungs after maximal expiration. The volume expired in the first second of a maximal expiration is a measure of airflow (FEV1), not the total exhaled amount, and the maximal inspiratory volume after a normal inspiration corresponds to inspiratory reserve volume, not the total exhaled volume.

Vital capacity is the maximum amount of air you can exhale after taking the deepest possible breath. It reflects how much usable air can be moved in one forceful breath and equals the sum of inspiratory reserve volume (air you can inhale beyond a normal breath), tidal volume (the normal breath you take), and expiratory reserve volume (air you can exhale beyond a normal breath). In other words, after a maximal inspiration, the total volume you can expel is the vital capacity. It does not include residual volume, which stays in the lungs after maximal expiration. The volume expired in the first second of a maximal expiration is a measure of airflow (FEV1), not the total exhaled amount, and the maximal inspiratory volume after a normal inspiration corresponds to inspiratory reserve volume, not the total exhaled volume.