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Anatomy of the Lymphatic System
The lymphatic system is part of the immune system. It helps the body fight infections. It also helps maintain the proper balance of fluids throughout the body. The lymphatic system has a series of thin tubes, called lymphatic vessels that collect fluid from different parts of the body. The thin tubes then take the fluid, called lymph, back to the heart. Lymph is a colorless, watery fluid that is rich in white blood cells, particularly lymphocytes.
Lymphocytes play an important role in the immune system by protecting the body against infection and the growth of tumors. At different places in the system, these lymphocytes form lymph nodes. A lymph node is about the size of a pea and has large numbers of lymphocytes. Groups of lymph nodes are found throughout the body. They can often be felt in the armpit, groin, and neck areas, especially if they become enlarged. Some of the body’s internal organs are also part of the lymphatic system. These organs are the bone marrow, spleen, thymus, and tonsils.
There are 2 main kinds of lymphocytes: B lymphocytes (B cells) and T lymphocytes (T cells). B cells and T cells have different functions in the immune system.
B cells fight bacteria by making antibodies. The antibodies attach to the bacteria and attract cells that eat the bacteria cells. The antibodies can also get proteins from the blood to help kill bacteria.
T cells help protect the body from fungi, viruses, and some bacteria. T cells are able to recognize viral proteins in virus-infected cells and then destroy the infected cells. Some T cells also release special proteins called cytokines, which bring white blood cells to the area of the infection. Other T cells can kill cancer cells.
Normal B cells and T cells can be recognized with certain lab tests. Each type of cell has features that the other does not. There are many stages of T-cell and B-cell growth, which can also be determined by lab tests.
Lymphoma is a type of cancer that can start in either T cells or B cells. The cancer cells in Hodgkin disease, which is a type of lymphoma, look very different from other lymphatic cancers. In most cases, the Hodgkin disease cancer cells are called Reed-Sternberg cells. These cells are usually an abnormal type of B cell.
Online ResourcesAmerican Cancer Society http://www.cancer.org/cancer/hodgkindisease/detailedguide/hodgkin-disease-what-is-hodgkin-disease
American Cancer Society http://www.cancer.org/docroot/CRI/content/CRI_2_4_1x_What_Is_Hodgkin_Disease.asp