The lymphatic system is very similar to and works alongside and directly alongside the cardiovascular system. The lymphatic system has a network of vessels like the circulatory system that pump a plasma-like fluid called lymph around its lymphatic vessels and are found in most other tissues of the body, except the central nervous system. Lymph is the name given to the fluid of plasma proteins that escape the circulatory system at sites of the capillary network and diffuse into the cells around the capillaries. To allow the body to maintain a homeostatic fluid level and pressure, lymph must be returned to the circulatory system. This occurs so that the network of lymphatic vessels collects the fluid that has leaked and has been absorbed by the cells at the open ends of the lymphatic vessels and transports it to a point where it can be reintroduced into the bloodstream. system. Two points in the shoulders called the left and right subclavian ducts are where lymph is reintroduced into the cardiovascular system. Inside the lymphatic vessels, the lymph is examined and checked for disease-causing organisms, bacteria, and dead cells at sites along the vascular network called lymph nodes. There are many lymph nodes within the vascular network of various sizes that have numerous entry points into the vessels, but only one exit point per node. There are 4-5 nodes per vessel and after the lymph has been sieved from the first node, it travels to the second, third etc., and can pass through up to 8 of them before reaching the subclavian ducts. This allows the nodes to analyze the lymph and act accordingly. If the node detects a pathogen, it releases antibodies called lymphocytes (white blood cells) to attack the foreign body and destroy it. Even the node... in the center of the paper... bones, in the T lymphocytes in the thymus. T cells are programmed to fight specific antigens that enter the body and distinguish between cells and tissues of the body and foreign bodies within the body. This foreign material is isolated by T lymphocytes and causes the immune system to react to the foreign material by destroying it. Since T cells are programmed to react only to specific antigens, they would have no effect on other antigens and therefore would need to be programmed to react to these. T lymphocytes enter the bloodstream; some enter the lymphatic system and the others circulate in the cardiovascular system. The Thymus gland grows from birth until adolescence where it reaches its peak. In addition to this, the thymus shrinks in size and actual capacity to produce T lymphocytes and, by middle age, is about the same size as at birth..