Biology · Breathing and Exchange of Gases · NEET
A volume is a single, basic amount of air that cannot be split further: Tidal Volume (TV, ~500 mL), Inspiratory Reserve Volume (IRV, 2500-3000 mL), Expiratory Reserve Volume (ERV, 1000-1100 mL) and Residual Volume (RV, 1100-1200 mL). A capacity is made by adding two or more of these volumes together. So in every numerical, first write the volumes you are given, then add the right ones to get the capacity asked.
EC = Tidal Volume + Expiratory Reserve Volume (TV + ERV). It is the total air you can expire after a normal inspiration. If TV = 500 mL and ERV = 1000 mL, then EC = 500 + 1000 = 1500 mL. Do NOT add Residual Volume here, even if the question gives it. RV is a common trap number placed to confuse you.
Residual Volume (RV) is NOT added. Vital Capacity = IRV + TV + ERV. RV is the air that can never be breathed out, so it is never part of Vital Capacity. Only Total Lung Capacity (TLC) includes RV, because TLC = VC + RV = everything the lung can hold.
TLC is the sum of all four volumes: TLC = IRV + TV + ERV + RV. You can also write it as TLC = Vital Capacity + Residual Volume. So if you already know VC, just add RV. Using NCERT values: 3000 + 500 + 1100 + 1200 = 5800 mL (roughly 5800-6000 mL).
FRC = ERV + RV. It is the air left in the lungs after a NORMAL (quiet) expiration. Residual Volume alone is the air left after a FORCED expiration. Because FRC also includes the ERV you can still push out, FRC is larger than RV. This ERV-versus-normal-expiration difference is a common exam confusion.
First identify the capacity asked and write its formula (IC = TV+IRV, EC = TV+ERV, FRC = ERV+RV, VC = IRV+TV+ERV, TLC = all four). Only pick the volumes named in that formula. Any leftover value is a distractor placed on purpose. NEET loves giving RV in a Vital Capacity or Expiratory Capacity question to test if you know RV is not counted there.
Tidal Volume and Expiratory Reserve Volume of an athlete is 500 mL and 1000 mL, respectively. What will be his Expiratory Capacity if the Residual Volume is 1200 mL?
Match List I with List II: List I: A. Expiratory capacity B. Functional residual capacity C. Vital capacity D. Inspiratory capacity List II: I. ERV + TV + IRV II. TV + ERV III. TV + IRV IV. ERV + RV
Vital capacity of lung is _______.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
TV = 500 mL, IRV = 2500-3000 mL, ERV = 1000-1100 mL, RV = 1100-1200 mL. From these: IC = TV+IRV (~3500 mL), EC = TV+ERV (~1500 mL), FRC = ERV+RV (~2300 mL), VC ~4600 mL, TLC ~5800-6000 mL.
No. Vital Capacity = IRV + TV + ERV only. Residual Volume is air that can never be forced out, so it is included only in Functional Residual Capacity (ERV+RV) and Total Lung Capacity (VC+RV).
TLC = Vital Capacity + Residual Volume, or written fully, TLC = IRV + TV + ERV + RV. It is simply the sum of all four respiratory volumes, the maximum air the lungs can hold.
Inspiratory Capacity = TV + IRV, the air you can breathe in after a normal expiration. Vital Capacity = IRV + TV + ERV, the total usable air. VC is larger because it also includes ERV, the extra air you can force out.
They test whether you know each capacity as a fixed sum of volumes and whether you can ignore distractor values like RV. They are quick, high-scoring, and repeat almost every year, so learning the five formulas guarantees easy marks.
