Volume of air in the lungs at the end of passive expiration
Functional residual capacity (FRC) is the volume of air present in the lungs at the end of passive expiration.[1] At FRC, the opposing elastic recoil forces of the lungs and chest wall are in equilibrium and there is no exertion by the diaphragm or other respiratory muscles.[1]
^ abHopkins E, Sharma S. Physiology, Functional Residual Capacity. [Updated 2022 Jan 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK500007/