Question

Distinguish between:
A. IRV and ERV
B. Inspiratory Capacity and Expiratory Capacity
C. Vital Capacity and Total lung capacity

Answer 1

Hint: All of the above values are respiratory capacities and lung volumes that are a part of the pulmonary function tests.

Complete answer: All of the above lung capacities and volumes are measured as a part of pulmonary function tests (PFTs) using a spirometer.

A) Difference between IRV and ERV:

IRV	ERV
It is the Inspiratory Reserve Volume	It is the Expiratory Reserve Volume
It is the maximum volume of air that can be inhaled after a normal inspiration	It is the maximum volume of air that can be exhaled after a normal expiration
The normal value is between 2500 – 3500 mL	The normal value is between 1000 – 1500 mL

B) Difference between IC and EC:

IC	EC
Inspiratory Capacity	Expiratory Capacity
It is the volume of air that can be inhaled after a normal expiration	It is the volume of air that can be exhaled after a normal inspiration
It is the sum of the Tidal Volume and Inspiratory Reserve Volume. IC = TV + IRV	It is the sum of Tidal Volume and expiratory reserve volume. EC = TV + ERV
The normal value is 3500 mL	The normal value is 800 – 1100 mL

C) Difference between VC and TLC:

VC	TLC
Vital Capacity	Total Lung Capacity
It is the maximum value of air that can be exhaled after a maximum inspiration	It is the volume of air in the lungs after a maximum inspiration
It is the sum of the IC and ERV	It is the sum of the IC, ERV, and RV
The normal value is 4000 mL	The normal value is about 5000 – 6000 mL

Note: It is an apparatus for measuring the volume of air inspired and expired by the lungs.
It measures ventilation, which is the movement of air into and out of the lungs.
The ventilation-perfusion ratio is another important part of PFT.