Functional Residual Capacity (FRC) is a medical term referring to the amount of air present in the lungs at the end of passive expiration. It can be estimated through spirometry. The heart and lungs (from an older edition of Grays Anatomy) The lung is an organ belonging to the respiratory system and interfacing to the circulatory system of air-breathing vertebrates. ... Spirometry (meaning the measuring of breath) is the most common of the Pulmonary Function Tests (PFTs), measuring lung function, specifically the measurement of the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled. ...

A lowered or elevated FRC is often an indication of some form of respiratory disease. Respiration can refer to: Cellular respiration, which is the use of oxygen in the metabolism of organic molecules. ...