Tidal Volume (TV) refers to which of the following?

• A. The volume of air inhaled or exhaled in a normal breath
• B. The maximum amount of air the lungs can hold
• C. The amount of air remaining in the lungs after exhalation
• D. The rate of air movement in and out per minute

Answer: (A)

Tidal volume is the amount of air moved in or out with a normal, relaxed breath. In quiet breathing, you inhale and exhale roughly the same amount each cycle, and that amount—the tidal volume—is typically around 0.5 liters in an average adult. This distinguishes it from other lung volumes: the maximum air the lungs can hold is the total lung capacity (or vital capacity for the max you can expel), the air remaining after a full exhale is the residual volume, and the rate of air movement per minute is minute ventilation (tidal volume multiplied by breathing rate). So the correct choice describes the typical volume exchanged in a normal breath.