Which statement defines tidal volume?

• 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 of the lungs during a normal, quiet breath. It reflects the typical inhalation and exhalation at rest and is usually about 500 milliliters in a healthy adult, though it varies with body size and breathing pattern. This differs from other lung measurements: the maximum air the lungs can hold is a larger volume such as total lung capacity or vital capacity, the air remaining after full exhalation is residual volume, and the rate of air movement per minute is minute ventilation (tidal volume multiplied by breathing rate). So the statement describing the normal breath volume best defines tidal volume.