Question

The inspiratory reserve volume + tidal volume + expiratory reserve volume is the same as
A. inspiratory capacity + expiratory reserve volume
B. total lung capacity - functional residual capacity
C. inspiratory capacity + functional residual capacity
D. inspiratory capacity + residual volume

Answer 1

Lungs volume usually measures the amount of air for a specific function, which can be measured by a spirometer, and lung capacities are the sum of 2 or more volumes, so different animals exhibit different lung capacities that too based on their activities.

Complete answer: The volume in the lung can be divided into four units, they are
Tidal volume(TV): It is the measure of the amount of air that is inspired and also expired during a normal breath. On average this volume is about half a liter.
Expiratory reserve volume(ERV): This volume tells about the additional amount of air that can be exhaled after the normal exhalation. So to simply say it is the reserved amount that can be exhaled beyond what is normal.
Inspiratory reserve volume(IRV): It is the additional amount of air that can be inhaled after a normal inhalation.
Residual volume(RV): It is the amount of air that is left after the expiratory reserve volume is exhaled.
By the above all one can understand that lungs are never empty, there is always some air that is left inside the lungs.
Residual volume is very important for preventing large fluctuations in respiratory gases.
Residual volume cannot be measured and It can only be calculated.
In the spectrometer technique, an important measure that is taken is forced expiratory volume(FEV).
FEV: It measures how much air can be forced out of the lung, for a specific period that is generally one second which can be denoted as FEV1.
FVC: It is the total amount of air that can be forcibly exhaled, the ratio of FVC is FEV1/FVC, which is generally used to diagnose lung diseases like emphysema.
Lung capacities: They are the measurement of the two or more volumes.
Vital capacity: Maximum amount of air that can be inspired or exhaled during the respiratory cycle.
VC= ERV + TV + IRV.
Inspiratory capacity: It is the amount of air that can be inhaled after the end of normal expiration.
IC= TV+IRV.
Functional residual capacity: It is the measure of the amount of additional air that can be exhaled after the normal exhalation.
Total lung capacity: It is the measurement of the total amount of air that the lung can have.
TLC= RV+ ERV+TV + IRV.
So we already know that inspiratory capacity = TV+IRV, so the answer is IC+ERV, so the correct option is A.

Note: Lung volumes and lung capacities refer to the volume of air in the lungs at different phases of the respiratory cycle, and the average lung capacities of the humans are about 30 to 60 breaths per minute at birth and it decreases to 12- 20 breaths per minute in adults.