Question

Vital Capacity is
A. RV + ERV
B. TV + IRV +ERV
C. TV + IRV
D. TV + ERV

Answer 1

Hint: Vital Capacity or VC is defined as the amount of air that can be expelled out from the lungs by a person after a forced inhalation. This is a part of lung capacities, which are measured to assess lung function. The method is known as Spirometry.

Complete answer: Vital capacity is measured as the sum of TV which is the tidal volume, IRV which is the inspiratory reserve volume, and ERV which is the expiratory reserve volume. The tidal volume is the volume of air which moves in and out of the lungs with each breath, IRV is the volume of air which goes into the lung after a forced inspiration, that is more than the tidal volume and ERV is the volume of air that is expelled after a forced exhalation.
Considering the other options:
-The sum of RV and ERV is known as the functional residual capacity or FRC. It is the residual amount of air remaining in the lungs after a normal exhalation.
-The sum of TV and IRV is known as the inspiratory capacity or IC which is the maximum amount of air that is followed by the resting state of the lungs.
-The sum of TV and ERV is known as the expiratory capacity or EC, which is the maximum amount of air exhaled after the resting state.
Thus, the most appropriate answer is B, i.e., Vital Capacity is the sum of TV, ERV and IRV.

Note: Lung volumes are an important part of the pulmonary function tests or PFTs which are used to measure the health status of the lungs. The capacities can be different from gender, body nature, and age. It is also affected by diseases that affect the lungs such as asthma.