Lymphatic Diseases
The lymphatic system is a network of tissues and organs. It is made up mainly of lymph vessels, lymph nodes and lymph. Lymph vessels, which are different from blood vessels, carry fluid called lymph throughout your body. Lymph contains white blood cells that defend you against germs. Throughout the vessels are lymph nodes. Along with your spleen, these nodes are where white blood cells fight infection. Your bone marrow and thymus produce the cells in lymph. They are part of the system, too.
The lymphatic system clears away infection and keeps your body fluids in balance. If it's not working properly, fluid builds in your tissues and causes swelling, called lymphedema. Other lymphatic system problems can include infections, blockage, and cancer.
Like the venous system, the lymphatic system transports fluids throughout the body. The lymphatic system consists of thin-walled lymphatic vessels, lymph nodes, and two collecting ducts. Lymphatic vessels, located throughout the body, are larger than capillaries, and most are smaller than the smallest veins. Most of the lymphatic vessels have valves like those in veins to keep the lymph, which can clot, flowing in the one direction. Lymphatic vessels drain fluids that have diffused through the very thin walls of capillaries. The fluids contain proteins, minerals, nutrients, and other substances, which provide nourishment to tissues.
However, most of the fluid is reabsorbed into the capillaries. The rest of the fluid (lymph) is drained from the spaces surrounding the cells into the lymphatic vessels, which eventually return it to the veins. Lymphatic vessels also collect and transport damaged cells, cancer cells, and foreign particles (such as bacteria and viruses) that may have entered the tissue fluids. All of lymph passes through strategically placed lymph nodes, which filter damaged cells, cancer cells, and foreign particles out of the lymph.
Lymph nodes also produce specialized blood cells designed to engulf and destroy damaged cells, cancer cells, and foreign particles. Thus, important functions of the lymphatic system are to remove damaged cells from the body and to provide protection against the spread of infection and cancer. The lymph vessels drain into collecting ducts, which empty their contents into the two subclavian veins, located under the collarbones.
These veins join to form the superior vena cava, the large vein that drains blood from the upper body into the heart. The lymphatic system may not perform its function adequately when the quantity of fluid is excessive or when the lymph vessels or nodes become blocked by a tumor or become inflamed.