Which term specifically describes the volume of air inhaled and exhaled in a standard breath?

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

Answer: (C)

The amount of air moved in and out during a normal, resting breath is tidal volume. It represents the typical volume exchanged with each quiet breath, about 500 mL in an average adult. This is distinct from air in the dead space—air in the conducting passages that doesn’t reach the alveoli for gas exchange—or from inspiratory reserve volume—the extra air you can inhaled beyond a normal breath. It’s also not vital capacity, which is the maximum air you can exhale after a full inhalation and includes tidal volume plus the reserve volumes. So the normal breath’s air volume is the tidal volume.