Question

The volume of air remaining in lungs after a forceful expiration is called:

• A. Tidal volume
• B. Residual volume
• C. Inspiratory reserve volume
• D. Vital capacity

Hint:

The Residual Volume (RV) cannot be measured using a simple spirometer because the air never leaves the respiratory system. It must be calculated using gas dilution methods.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Respiratory volumes represent different quantities of air inhaled, exhaled, or remaining in the lungs during various phases of the breathing cycle.
Even after a person performs the most forceful expiration possible, the lungs are never completely empty of air.

Step 2: Detailed Explanation:
1. Tidal Volume (TV): This is the volume of air inspired or expired during a normal, relaxed breath, which is approximately \(500\) mL in a healthy adult.
2. Residual Volume (RV): This is the specific volume of air that remains trapped in the lungs even after a maximum forced expiration. This volume ensures that the lungs do not collapse and that gas exchange continues even between breaths. Its typical value ranges from \(1100\) mL to \(1200\) mL.
3. Inspiratory Reserve Volume (IRV): The additional volume of air that can be inhaled forcibly after a normal inspiration.
4. Vital Capacity (VC): The maximum volume of air a person can breathe out after a maximum inhalation, encompassing TV, IRV, and ERV.

Step 3: Final Answer:
The volume of air that remains in the lungs after forceful expiration is the Residual Volume.