Lymphatic System

• The lymphatic system consists of lymphatic vessels, lymph, lymphocytes, and lymphoid tissues
• Lymphoid tissues include lymphoid nodules and organs
• Lymphatic capillaries provide drainage for accumulating fluid that leaks from blood capillaries
• The fluid, lymph, contains many lymphocytes and a small amount of white blood cells.
• lymphatic vessels transport lipids and lipid-soluble vitamins absorbed by the gastrointestinal tract to the blood.
• lymphocytes initiate specific immune responses that provide protection for the body against disease and infection
• Lymph structures smallest to largest: capillaries, vessels, trunks, ducts
• Primary lymphoid organs are the bone marrow and thymus gland
• Bone marrow is the soft tissue inside the bones that produces B cells
• The thymus matures T cells
• Secondary lymphatic organs include the Spleen, Lymph nodes, and Lymphatic nodules.
• Lymph nodes funciton to remove debris and pathogens from the lymph, and are thus sometimes referred to as the “filters of the lymph”
• lymph nodes are the site of adaptive immune responses mediated by T cells, B cells, and accessory cells.
• Lymph enters the node through the afferent vessel then leaves through the efferent vessel
• the Spleen functions in removing microbes and other materials from the blood, including dying red blood cells, providing repsonses to blood-borne pathogens
• What do secondary organs all have in common

  Lymphoid follicles, sites to form lymphocytes, rich B and T cell areas, Germinal centers, high endothelial venules
• Lymph Nodules consist of large clusters of lymphocytes
• Nodules are located in the digestive, respiratory, and urinary systems. All tracts that are exposed to the outer environment
• Tonsils protect from oral pathogens by accumulating materials from eating and breathing
• The three tonsils are Pharyngeal(1), palatine(2), and lingual(2)
• Mucosa Associated Lymphoid Tissue (MALT) is a collection of lymphoid follicles in tissue of the gastrointestinal tract
• Peyer's Patches are examples of MALT