Residual volume is defined as which of the following?

Residual volume is defined as which of the following?

• A. Amount of air remaining in the lungs after a forced exhalation
• B. Amount of air moved in and out of the lungs during a normal breath
• C. Total volume of air that can be exhaled after maximal inhalation
• D. The maximum amount of air that can be inhaled after a deep breath

Answer: (A)

Residual volume is the amount of air left in the lungs after you exhale as forcefully as possible. This remaining air can’t be expelled, even with maximum effort, and it helps keep the airways open between breaths to maintain gas exchange. It’s different from tidal volume, which is the air moved in and out during a normal breath. It’s also distinct from vital capacity, the total air that can be exhaled after a maximal inhalation, and from the maximal amount you can inhale after a deep breath (inspiratory capacity). Therefore, the air remaining after a maximal exhalation best describes residual volume.

Residual volume is the amount of air left in the lungs after you exhale as forcefully as possible. This remaining air can’t be expelled, even with maximum effort, and it helps keep the airways open between breaths to maintain gas exchange. It’s different from tidal volume, which is the air moved in and out during a normal breath. It’s also distinct from vital capacity, the total air that can be exhaled after a maximal inhalation, and from the maximal amount you can inhale after a deep breath (inspiratory capacity). Therefore, the air remaining after a maximal exhalation best describes residual volume.