The term means the lung performs the physiological function of assisting the heart in promoting blood circulation throughout the body. All meridians and vessels which carry qi and blood converge in the lung, fulfilling the exchange of qi via the lung and then distributing qi and blood all over the body. The term has three meanings. First, the blood in the whole body flows upward to the lung along the vessels. Second, the fresh air inhaled by the lung integrates with the essential qi from nutrients of food and drinks transformed and transported by the stomach and the spleen to form pectoral qi, which assists the heart in promoting blood circulation. Third, the lung regulates qi movement and influences blood circulation.