Question

Which of the following respiratory volumes represents the air remaining in the lungs after forced expiration?

• A. Tidal Volume (TV)
• B. Inspiratory Reserve Volume (IRV)
• C. Residual Volume (RV)
• D. Vital Capacity (VC)

Hint:

Residual volume always remains in the lungs and cannot be expelled, even after forceful expiration. It helps keep alveoli open and prevents lung collapse.

Answer 1

The Correct Option is C

Concept: Different respiratory volumes describe the amount of air moving in and out of the lungs during breathing. Residual Volume (RV) is the volume of air that remains in the lungs even after a forceful expiration.

Step 1: Understand residual volume. Residual Volume is the amount of air that remains in the lungs after the most forceful exhalation possible.

Step 2: Importance of residual volume. Residual volume prevents the lungs from collapsing and ensures continuous gas exchange between breaths.

Step 3: Approximate value. In a healthy adult, the residual volume is approximately: \[ RV \approx 1100-1200 \ \text{mL} \]

Step 4: Differentiate from other lung volumes.
• Tidal Volume (TV): Air inhaled or exhaled in normal breathing.
• Inspiratory Reserve Volume (IRV): Extra air that can be inhaled after normal inspiration.
• Vital Capacity (VC): Maximum air that can be exhaled after maximum inspiration.