What does Functional Residual Capacity (FRC) include?

Functional Residual Capacity (FRC) is the volume of air remaining in the lungs after a normal expiration. It is an important measure in respiratory physiology as it represents the balance between the amount of air left in the lungs and the pressure exerted by the elastic recoil of the lung tissues and chest wall.

FRC is composed of two volumes: Residual Volume (RV) and Expiratory Reserve Volume (ERV). RV is the amount of air that remains in the lungs after a maximal exhalation, preventing the alveoli from collapsing completely, while ERV is the amount of air that can be forcefully exhaled after a normal expiration. When these two volumes are added together, they provide the total volume of air that remains in the lungs after a typical breathing cycle, which is what FRC represents.

Understanding FRC is critical in various clinical scenarios, especially in critical care settings, as it helps assess lung function and the potential for gas exchange. Recognizing its components assists healthcare providers in evaluating and managing patients with respiratory issues.