Question

A student takes a normal breath in. He then inhales as deeply as possible until he cannot inhale anymore. The amount of air that he breathed in after the normal breath is his ____________.

a) inspiratory capacity.

b) inspiratory reserve volume.

c) tidal volume.

d) vital capacity.

Answer 1

b) inspiratory reserve volume.

Explanation:

Four types of lung volumes are

1) Tidal volume:
It is the amount of air that can be inhaled or exhaled during one respiratory cycle.
The normal adult value is 300-500ml.

2) Inspiratory Reserve Volume
It is the amount of air that can be forcibly inhaled after a normal tidal volume. IRV is usually kept in reserve, but is used during deep breathing. The normal adult value is 1900-3300ml.

3) Expiratory Reserve Volume
It is the volume of air that can be exhaled forcibly after exhalation of normal tidal volume. The normal adult value is 700-1200ml.

4) Residual volume
It is the volume of air remaining in the lungs after maximal exhalation. Normal adult value is 1200ml.

Lung capacities
1) Inspiratory capacity(IC):
It is the maximum volume of air that can be inhaled following a resting state. It can be calculated from the sum of inspiratory reserve volume and tidal volume. IC = IRV+TV

2) Total Lung Capacity(TLC):
It is the maximum volume of air the lungs can accommodate or sum of all volume compartments or volume of air in lungs after maximum inspiration. The normal value is about 6,000mL(4‐6 L). TLC is calculated by summation of the four primary lung volumes (TV, IRV, ERV, RV).

3) Vital Capacity(VC):
It is the total amount of air exhaled after maximal inhalation. The value is about 4800mL and it varies according to age and body size. It is calculated by summing tidal volume, inspiratory reserve volume, and expiratory reserve volume. VC = TV+IRV+ERV.

4) Function Residual Capacity(FRC):
It is the amount of air remaining in the lungs at the end of a normal exhalation. It is calculated by adding together residual and expiratory reserve volumes. The normal value is about 1800 – 2200 mL. FRC = RV+ERV.