The lymphatic system consists of lymph nodes, or glands, connected by a network of lymphatic vessels that extends to all parts of the body. The system drains a fluid called lymph from the body’s tissues back into the bloodstream. It also protects the body against infection and the development of cancer by filtering out infectious organisms and cancerous cells from the lymph.
Lymph, a fluid that contains white blood cells called lymphocytes, fats, and protein, flows along the network of lymphatic vessels and ultimately re-enters the bloodstream from which it originally came. Along the way, lymph is filtered through the lymph nodes, which are located in clusters close to the skin’s surface in the neck, armpits, and groin. Nodes are also found deep within the abdomen and chest. The lymph nodes contain large numbers of lymphocytes, white blood cells that can destroy infectious organisms or cancer cells. Lymphocytes can also develop into cells that produce antibodies, which help other white blood cells trap and destroy infectious organisms and cancer cells throughout the body.
The first article in this section covers lymphadenopathy, in which the lymph nodes become enlarged. A painful swelling of the lymph nodes is not often a cause for concern, but painless swelling may be a sign of a serious underlying disorder, such as cancer. The next articles cover lymphangitis, in which lymphatic vessels are inflamed, and lymphoedema, in which lymph cannot drain from a limb, causing the limb to swell. In developed countries, a common cause of lymphoedema is surgery or radiotherapy for cancer. The final article discusses lymphomas, a group of cancers that may develop in one or more lymph nodes.
For more information on the structure and function of the lymphatic system, see Formation of Blood Cells.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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