Functional Residual Capacity — FRCA Primary MCQ

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EasyPhysiology - RespiratoryFunctional Residual CapacityFRCA Primary

The functional residual capacity (FRC) is the sum of which two lung volumes?

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Correct answer: A — Residual volume and expiratory reserve volume

The correct answer is A. Functional residual capacity is the volume of gas remaining in the lungs and airways at the end of a normal tidal expiration. It comprises the residual volume, which remains after maximal expiration, plus the expiratory reserve volume, which can be expired from the end-tidal expiratory position: FRC = RV + ERV. Tidal volume is therefore not a component of FRC. In particular, tidal volume plus inspiratory reserve volume (option D) forms the inspiratory capacity, while the other combinations do not define FRC.

Reference: Association for Respiratory Technology and Physiology. ARTP statement on pulmonary function testing 2020: Definitions and calculation of lung-volume subdivisions. BMJ Open Respiratory Research 2020;7:e000575. https://bmjopenrespres.bmj.com/content/7/1/e000575