|Human Physiology 6/e Fox|
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Disorder of the Lymphatic System
It is not surprising that many infectious diseases produce symptoms associated with the lymphatic system, because the lymphatic system is involved with the production of lymphocytes that fight infectious disease, and the lymphatic system filters blood and lymph to remove microorganisms.
Lymphadenitis (lim-fad-e-ni'tis) an inflammation of the lymph nodes, which causes them to become enlarge and tender. It is an indication that microorganisms are being trapped and destroyed within the lymph nodes. Sometimes the lymphatic vessels become inflamed to produce lymphangitis (lim-fan-ji'tis). This often results in visible red streaks in the skin that extend away from the site of infection. If the microorganisms pass through the lymphatic vessels and nodes to reach the blood, septicemia, or blood poisoning, can result.
Bubonic plague and elephantiasis are diseases of the lymphatic system. In the sixth, fourteenth, and nineteenth centuries the bubonic plague killed large numbers of people. Fortunately there are relatively few cases today. Bubonic plague is caused by bacteria that are transferred to humans from rats by the bite of the rat flea. The bacteria localize in the lymph nodes, causing the lymph nodes to enlarge. The term bubonic is derived from a Greek word referring to the groin because the disease often causes the inguinal lymph nodes of the groin to swell. Without treatment, the bacteria enters the blood, multiply, and infect tissues throughout the body, rapidly causing death in 70% to 90% of those infected.
Elephantiasis (el-e-fan-ti'a-sis) is caused by long, slender roundworms. The adult worms lodge in the lymphatic vessels and cause blockage of lymph flow. The accumulation of fluid in the interstitial spaces and lymphatic vessels that results can cause permanent swelling and enlargement of a limb. The affected limb supposedly resembles an elephant's leg, providing the basis for the name of the disease. The offspring of the adult worms pass through the lymphatic system into the blood, from which they can be transferred to another human by mosquitoes.
A lymphoma (lim-fo'mah) is a neoplasm (tumor) of lymphatic tissue. Lymphomas are usually divided into two groups: (1) Hodgkin's disease, and (2) all other lymphomas, which are called non-Hodgkin's lymphomas. Typically, lymphomas begin as an enlarged, painless mass of lymph nodes. The immune system is depressed, and the patient has an increased susceptibility to infections. Enlargement of the lymph nodes can also compress surrounding structures and produce complications. Fortunately, treatment with drugs and radiation is effective for many people who suffer from lymphoma.
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