Which term describes the amount of air inhaled or exhaled in one breath?

• A. Tidal Volume
• B. Residual Volume
• C. Dead Space
• D. Inspiratory Reserve Volume

Answer: (A)

Tidal volume is the amount of air moved in and out of the lungs with each normal breath. It represents the typical, resting ventilation per breath—usually about 500 mL in an average adult, though it varies with size and activity. This is different from residual volume, which is the air left in the lungs after a full exhalation and cannot be voluntarily expelled. Dead space is the portion of air in the conducting airways that does not reach the alveoli for gas exchange. Inspiratory reserve volume is the extra air you can inhale beyond the normal tidal volume if you take a deep breath. So tidal volume describes your regular breath, while the others describe air that remains in the lungs after exhalation, air that doesn’t participate in gas exchange, or extra capacity during a forced inhalation.