Which respiratory volume has a normal value of 500 mL in a healthy adult?

• A. Inspiratory reserve volume
• B. Tidal volume
• C. Residual volume
• D. Expiratory reserve volume

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the concept of respiratory volumes. Respiratory volumes are measurements of air movement during different phases of breathing. These include tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume.
2. Step 2: Define tidal volume. Tidal volume refers to the amount of air inhaled or exhaled during a normal, relaxed breath. In a healthy adult, this volume is typically around 500 mL.
3. Step 3: Define inspiratory reserve volume. Inspiratory reserve volume is the additional amount of air that can be inhaled after a normal inhalation, typically much larger than tidal volume.
4. Step 4: Define expiratory reserve volume. Expiratory reserve volume is the additional amount of air that can be exhaled after a normal exhalation, also larger than tidal volume.
5. Step 5: Define residual volume. Residual volume is the amount of air remaining in the lungs after a maximal exhalation, which cannot be voluntarily expelled. This volume is much greater than 500 mL and serves to keep the lungs inflated.