The Lymphatic System
The lymphatic system is a network of vessels carrying lymph, or tissue-cleansing fluid, from the tissues into the veins of the circulatory system. The lymphatic system functions along with the circulatory system in absorbing nutrients from the small intestines. A large portion of digested fats are absorbed via the lymphatic capillaries. Like the blood circulatory system, the lymphatic system is composed of fine capillaries that lie adjacent to the blood vessels. These merge into larger tributaries known as trunks, and these in turn merge into two still larger vessels called ducts. The thoracic and right lymphatic ducts empty into the venous system in the region of the collarbones. Lymph, a colorless fluid whose composition is similar to that of blood except that it does not contain red blood cells or platelets, and contains considerably less protein, is continuously passing through the walls.