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The Lymphatic System. Along with the blood circulatory system, mammals have a 2 nd circulatory system called the Lymphatic system. This is a one way system of dead ending vessels These vessels collect fluid around cells and return it to the blood.
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Along with the blood circulatory system, mammals have a 2nd circulatory system called the Lymphatic system. • This is a one way system of dead ending vessels • These vessels collect fluid around cells and return it to the blood. • Lymph nodes are swellings in the lymph vessel, these help to fight infection
Because blood in arteries are under high pressure they force out some fluid through the capillaries. This fluid is called tissue fluid and surrounds all the cells of the body. Formation of Lymph
Tissue fluid is similar to plasma as it contains small amounts of white blood cells & proteins but no red blood cells or platelets. It acts as an exchange medium whereby materials entering/leaving cells must pass through. Formation of Lymph
Formation of Lymph • Because it is believed that life originated in the sea, it is interesting that our cells still need to be surrounded by water to function. • As tissue fluid is being formed it must be removed & returned to the blood. • This prevents swelling (called oedema) from developing in the tissues.
Tissue fluid is drained away by 2 routes 90% goes back into capillaries near veins. This occurs by osmosis. 10% enters dead ending tubes called lymph vessels. This fluid is now called Lymph which contain large amounts of white blood cells, proteins & fats Formation of Lymph
Lymph Vessels Found throughout the body • Lymph (tissue fluid) is moved through the vessels by muscular walls & general body movements pressing on the vessels. • A system of valves ensure one way flow.
2 main vessels Thoracic duct on left side of body Right lymphatic duct at the right shoulder These ducts empty lymph into the bloodstream at the subclavian veins located near the collar bones at the shoulders. Lymph Vessels
Small swellings found along lymph vessels. Contain large no. of white blood cells with many channels the lymph can flow through. Formed in clusters, which form glands i.e. Tonsils, adenoids, neck, armpits, thymus, spleen & groin. Lymph Nodes
Lymph Nodes • They fight infection in 2 ways • They filter bacteria • They store large no. of white blood cells called Lymphocytes. Some kill pathogens directly while others make antibodies • When they are fighting disease they swell i.e. swollen tonsils if you have a sore throat/cold • If lymph vessel get blocked, swelling occurs
Function of Lymphatic System • To collect tissue fluid & return it to the blood. • To absorb & transport fats in the digestive system. Lymph found in lacteals (villi in small intestine) • To help with hearing & balance in the ear • To defend the body against infection • Filtering out micro-organisms in lymph nodes • Maturing & storing lymphocytes • Destroying micro-organisms by engulfing & digesting them or anti-body production