Lymphatic System Health Article

Role in human health

The lymphatic system has a variety of roles in human health ranging from returning fluid from organs back to the circulatory system, to an important part in the human immune response, to absorbing lipids from the intestines. The defining role of the lymphatic vessels is to return any fluid that has leaked from the capillaries and into the interstitial space back to the circulatory system through the veins. This is important because if fluid was retained in the tissues, the result in reduced blood volume and swelling of the tissues.

Another important role of the lymphatic system is the ability of plasma proteins to fit through the lymphatic valves and into the lymphatic capillary. Since most proteins have such a high molecular weight, they are unable to be reabsorbed by venous capillaries. With out the reabsorption of the plasma proteins, humans can die within 24 hours.

The lymphatic system also has an essential role in the process of digestion. Primarily, the lymphatic capillaries in the gastrointestinal tract are one of the main routes for fats to be absorbed. Fats enter the lymphatics before entering the blood stream.

High molecular weight proteins are not the only large substances that are absorbed. Microorganisms such as bacteria can also fit between the endothelial cells of the terminal end of the lymphatic capillary. As this occurs and the bacteria are transported to the next lymph node, the meshwork of the node and sinuses with in the node act as a filter, catching and trapping the foreign organisms. Once trapped, microorganisms can be attacked by the concentrated cells of the immune system. Macrophages may consume disease-causing bacteria, Blymphocytes may come into contact with the antigens on the surface of the microorganism and stimulate antibodies, and T-lymphocytes called "killer" cells that attach themselves to the foreign organism and release a substance to destroy the organism. The destructive nature of the "killer" cells is enhanced by another T-lymphocyte called "helper" cells (T-helper cells also assist B-cells). If this system fails, then microorganisms are not destroyed, resulting in the spread of infection though the lymphatic system and extreme infection possibly leading to death.

Cancer cells that have lost adherence to, and break away from, the primary tumor are collected by the lymphatic system and filtered by latticework within the lymph nodes. Within the lymph node T-cells release substances called lymphokine (e.g. gamma interferor and interleukin 2) that may help destroy the cancer cells. Doctors use the lymph nodes as one factor of evaluation when determining the stage of the cancer. In other words, when determining how far the cancer has progressed at the time of diagnosis, the lymph nodes can be dissected to determine if cancer has spread (metastisized) from the original tumor or not. If cancer cells are present in the lymph nodes, then the cancer receives a higher stage and a less-optimistic diagnosis. In cancers that metastasize via the lymphatics, the lymph nodes where cancer cells are present are often removed. This is even more common when the lymph nodes in question are adjacent to the tumor, when the lymph nodes are located on the only lymphatic vessel present in the area of the tumor, or if no other lymphatics will be damaged during the removal.

Common diseases and disorders

Since the lymphatic system is responsible for draining excess fluid from tissues and organs, the most common symptom of diseases and disorders of the lymphatic system is swelling. For example, a disease known as elephantiasis, which is caused by a filarial worm infestation, involves the blockage of the lymphatics. When the lymphatics are blocked, fluid cannot be drained and swelling occurs in the affected areas. Administering ethyl-carbamazine drugs, elevating the area and wearing a compression stocking can treat elephantiasis.

Tonsillitis is another disease of the lymphatic system. Tonsillitis usually involves a bacterial or viral infection located within the tonsils. The tonsils are swollen, and the patient experiences a fever, sore throat, and difficulty swallowing. This can be treated by the use of antibiotics or through a surgical procedure called a tonsillectomy.

A condition common among individuals following surgery for breast cancer or prostate cancer is lymphedema. It is caused by blockage of lymph vessels or lymph nodes located near the surgical site and can result in swollen arms or legs. If microorganisms cause the swelling, then antibiotics are used as treatment. If microorganisms are not the cause, then compression garments and message therapy are used as treatment.

There are also cancers called lymphosarcomas and cancers of the lymph nodes that can affect the lymphatic system. The causes of these cancers are not known and there is not a consensus on what preventative measures can be taken to reduce the risk of developing these cancers. Symptoms of cancers affecting the lymphatic system include loss of appetite, energy, and weight, as well as swelling of the glands. As with many cancers, treatment includes surgical removal followed by adjuvant radiation and chemotherapy.