What does the term tidal Volume describe?

• A. Volume of air remaining after expiration
• B. Volume of air inhaled or exhaled with each breath under resting conditions
• C. Total lung capacity
• D. Inspiratory reserve volume

Answer: (B)

Tidal volume is the amount of air moved in or out of the lungs with each normal breath during quiet, resting breathing. In an average adult, this is about 500 mL per breath, though it varies with body size and conditions. This value reflects resting ventilation, not the maximum or reserve air. It differs from residual volume, which is the air remaining in the lungs after a full exhale; from inspiratory reserve volume, which is the extra air you can inhale beyond a normal inhalation; and from total lung capacity, which is the maximum air the lungs can hold after a deep inspiration. Tidal volume is a key component in calculating minute ventilation when combined with breathing rate.