The physiological significance of lymphatic reflux mainly includes recovery of proteins from tissue fluid, transport of fat absorbed by the small intestine, participation in immunity, and maintenance of plasma volume. The lymphatic duct system is an important auxiliary system for the return of tissue fluid to the blood. Lymphatic fluid from the whole body is collected by the lymphatic ducts and finally introduced into the veins by the right lymphatic duct and the thoracic duct.1. Recovery of proteins in tissue fluid: lymphatic reflux is mainly to bring back part of the tissue fluid, especially the protein molecules in the tissue fluid, to the blood, and is the only way for the proteins in the tissue fluid to return to the blood circulation. If lymphatic reflux is obstructed, the colloid osmotic pressure of tissue fluid will rise, which in turn will cause tissue edema; 2. Transport of fat absorbed by the small intestine: the capillary lymphatics of the small intestinal villi have a more important role in the absorption of nutrients, and most of the fat absorbed by the intestine is transported into the blood through lymphatic reflux; 3. Participation in immunity: lymphatic reflux also removes the tissue fluid that cannot be reabsorbed by capillaries Larger molecules, as well as red blood cells and bacteria in tissues, etc. Lymphocytes are related to the immune function of the body; 4. Maintaining plasma volume: The circulatory system includes the cardiovascular system and the lymphatic system. The lymphatic system is part of the circulatory system, and the lymphatic circulation can return part of the tissue fluid into the circulating blood, and a smooth lymphatic reflux can maintain normal plasma volume.