Hodgkin lymphoma (HL) is a type of cancer that starts in the lymphatic system. The lymphatic system works with the circulatory system and the immune systemimmune systemThe complex group of cells and organs that defend the body against infection, disease and foreign substances. – the body’s natural defence against infection and disease. It is made up of the spleen, thymus, tonsils, adenoids, bone marrow and a network of lymph nodes throughout the body that are connected by lymph vessels. Lymphatic tissue (which stores infection-fighting cells) is also found in other parts of the body, including the stomach, intestines and skin.
Lymph (lymph fluid) is a clear, yellowish fluid that carries white blood cellswhite blood cellsA type of blood cell that helps the body fight infection and diseases. (lymphocyteslymphocytesA type of white blood cell that fights viruses, bacteria, foreign substances or abnormal cells (including cancer cells).), antibodiesantibodiesA type of protein made by the immune system that disarms or destroys a specific foreign substance (antigen) when it appears in the body. and nutrients throughout the body. The lymph flows through the network of lymph nodes and vessels.
Lymphocytes are a type of white blood cell important to the immune system. There are 2 types:
Lymphocytes start to develop in the bone marrow. The B cells and T cells mature in different places:
There are 3 main types of lymph vessels:
Lymph nodes are small, bean-shaped organs that filter lymph. Lymph nodes vary in size but are usually less than 2.5 cm (1 inch) across. There are many lymph nodes throughout the body. The number of lymph nodes varies from one part of the body to another.
Lymph nodes contain 2 types of white blood cells that fight invading micro-organisms:
Lymph nodes are located in groups in the following major locations:
The main functions of the lymph nodes are to:
If a large number of particles are filtered through a lymph node or group of nodes, they may swell and become tender to the touch. For example, a sore throat may cause the lymph nodes under the jaw and in the neck to swell.
The spleen is the largest lymphatic organ. It is located in the upper-left abdomen. The spleen:
The thymus is located in the chest behind the breastbone (sternum). It is where T lymphocytes mature and multiply.
The tonsils are 2 small masses of lymphatic tissue in the throat that contain lymphocytes.
The adenoids are actually a single, small mass of lymphatic tissue in the back of the nose (nasopharynxnasopharynxThe upper part of the pharynx (throat) behind the nose and above the soft palate (the back, soft part of the roof of the mouth).) that contains lymphocytes. Although they are often called adenoids there is only one adenoid. The adenoid is also sometimes called the pharyngeal tonsil. The adenoids are present in infants and children, and start to shrink just before puberty. They are usually absent in adults.
Bone marrow is soft, spongy tissue in the centre of certain bones. It contains immature blood cells called stem cells. Stem cells develop into:
The main functions of the lymphatic system are to:
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