Question

From the following relationships between respiratory volume and capacities and mark the correct answer.

i. Inspiratory capacity (IC) = Tidal Volume + Residual Volume

ii. Vital Capacity (VC) = Tidal Volume (TV) + Inspiratory Reserve Volume (IRV) + Expiratory Reserve Volume (ERV)

iii. Residual Volume (RV) = Vital Capacity (VC) – Inspiratory Reserve Volume (IRV)

iv. Tidal Volume (TV) = Inspiratory Capacity (IC) – Inspiratory Reserve Volume (IRV)

Answer 1

Inspiratory capacity (IC)

The total volume of air that can be inspired after a normal expiration. It is the sum of the Tidal volume and the Inspiratory reserve volume.
IC = TV + IRV

Vital capacity (VC)

Vital capacity is defined as the maximum volume of air a person can breathe in after a forceful expiration or the maximum volume of air that can be breathed out by a person after forceful inspiration. It is calculated by summing tidal volume, inspiratory reserve volume, and expiratory reserve volume.
VC = TV + ERV + IRV

Residual volume (RV)

The volume of air that remains in the lungs even after a forceful expiration is known as residual volume. It is calculated by subtracting the vital capacity from the total lung capacity.
RV = TLC - VC

Tidal Volume (TV)

During normal breathing, the volume of air inspired or expired by a person is known as tidal volume. It can be calculated by subtracting the Inspiratory reserve volume from the Inspiratory capacity.
TV = IC - IRV

Final answer
b. (i) Incorrect, (ii) Correct, (iii) Incorrect, (iv) Correct