16 lymph, immunity 118

16 lymph, immunity 118 - Biology 118 16. LYMPHATIC SYSTEM,...

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Biology 118 16. LYMPHATIC SYSTEM, IMMUNITY FUNCTIONS : The lymphatic system’s main functions include The production and maintenance of lymphocytes. The return of fluid to the blood (up to 3.5-4 L per day). The transport of some nutrients and hormones. LYMPHATIC VESSELS : as the lymphatic system collects extracellular fluid, its vessels are associated with the blood vascular system, and include lymphatic capillaries, larger vessels, and the thoracic duct – this vessel returns fluid back into the blood vascular system. LYMPHOID NODULES : these nodules consist of connective tissue and lymphocytes, and are located beneath various interior epithelia in the body. As these nodules are not surrounded by a tough capsule, they can swell or shrink depending on the body’s immune status – tonsils and the appendix are full of these nodules, and so can become swollen when infected. LYMPHOID ORGANS : these are surrounded by a tough capsule. Lymph nodes – located along the lymph vessels, lymph passes through them. Inside, lymphocytes filter the fluid, capturing and destroying most of the antigens present. Thymus – located in the chest, behind the sternum. T-cells propagate and mature in the thymus. Spleen – this organ, populated with B and T lymphocytes, and with macrophages, filters the blood of antigens. LYMPHOCYTES : these are white blood cells, generally kept in the lymphoid organs until required. Some lymphocytes are long-lived – surviving up to decades. T-cells – there are three types: Cytotoxic T-cells – these can rove through the blood and tissues, and kill foreign cells and infected cells. Helper T-cells – these stimulate T and B cells. Suppressor T-cells – inhibit T and B cells.
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This note was uploaded on 11/02/2011 for the course BIO 118 taught by Professor Bilgen during the Winter '08 term at University of Washington.

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16 lymph, immunity 118 - Biology 118 16. LYMPHATIC SYSTEM,...

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