Question

Vital capacity of lung is _________.

• A. IRV + ERV + TV + RV
• B. IRV + ERV + TV – RV
• C. IRV + ERV + TV
• D. IRV + ERV

Answer 1

The Correct Option is C

The question asks about the components that make up the "vital capacity" of the lungs. Let's understand the terms involved before we arrive at the correct answer:

• IRV (Inspiratory Reserve Volume): This is the additional amount of air that can be inhaled after a normal inhalation.
• ERV (Expiratory Reserve Volume): This is the additional amount of air that can be exhaled after a normal exhalation.
• TV (Tidal Volume): This is the amount of air inhaled or exhaled during a normal breath.
• RV (Residual Volume): This is the volume of air remaining in the lungs after a forceful exhalation.

Vital Capacity (VC) is defined as the maximum amount of air a person can exhale after a maximum inhalation. Therefore, it is the sum of the Tidal Volume (TV), Inspiratory Reserve Volume (IRV), and Expiratory Reserve Volume (ERV).

The formula for Vital Capacity is:

VC = IRV + ERV + TV

Given the options, we can rule out the ones including Residual Volume (RV) since it does not contribute to the air that can be actively exchanged:

• Option 1: IRV + ERV + TV + RV - This is incorrect because it includes RV, which is not part of VC.
• Option 2: IRV + ERV + TV - RV - This is incorrect as VC does not involve subtracting RV.
• Option 3: IRV + ERV + TV - This is the correct option as it accurately represents the formula for Vital Capacity.
• Option 4: IRV + ERV - This is incorrect as it does not include TV.

Hence, the correct answer is the third option, IRV + ERV + TV.