The amount of air moving in or out of the lungs with each respiratory cycle is known as what?

• A. Tidal Volume
• B. Residual Volume
• C. Inspiratory Reserve
• D. Expiratory Reserve

Answer: (A)

Tidal volume is the amount of air moving in or out of the lungs with each normal breath. It reflects the volume exchanged during a typical respiratory cycle at rest. In a healthy adult, this is about 500 mL per breath, though it varies with body size and breathing effort. This distinguishes it from residual volume, which is the air left in the lungs after a full exhale and cannot be expelled in a normal breath; inspiratory reserve is the extra air you can inhale beyond a normal inhale; and expiratory reserve is the extra air you can exhale beyond a normal exhale. Because the question describes the air moved with each regular breath, tidal volume is the best fit.