Breathing and Exchange of Gases Question 18
18. What is vital capacity of our lungs?
[1988]
(a) Inspiratory reserve volume plus tidal volume
(b) Total lung capacity minus expiratory reserve volume
(c) Inspiratory reserve volume plus expiratory reserve volume
(d) Total lung capacity minus residual volume
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Answer : d
Hints & Solution
(d) Vital capacity of lungs is the largest possible expiration after largest possible inspiration that is greatest. Volume of air can be exchanged in single respiration or amount of air breathed in and out with greatest possible efforts. $ \begin{aligned} VC & =TRV+TV+ERV \\ & =3000+500+1100 \\ & =4600 ml . \end{aligned} $
