1. The Lymphatic System

2. Along with the blood circulatory system, mammals have a 2 nd circulatory system called 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 This is a one way system of dead ending vessels These vessels collect fluid around cells and return it to the blood. 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 Lymph nodes are swellings in the lymph vessel, these help to fight infection

5. Formation of Lymph Because blood in arteries are under high pressure they force out some fluid through the capillaries. 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. This fluid is called tissue fluid and surrounds all the cells of the body.

6. 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. 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. It acts as an exchange medium whereby materials entering/leaving cells must pass through.

7. 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. 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. As tissue fluid is being formed it must be removed & returned to the blood. This prevents swelling (called oedema) from developing in the tissues. This prevents swelling (called oedema) from developing in the tissues.

8. Formation of Lymph Tissue fluid is drained away by 2 routes Tissue fluid is drained away by 2 routes 1. 90% goes back into capillaries near veins. This occurs by osmosis. 2. 10% enters dead ending tubes called lymph vessels. This fluid is now called Lymph which contain large amounts of white blood cells, proteins & fats

9. Lymph Vessels Found throughout the body Lymph (tissue fluid) is moved through the vessels by muscular walls & general body movements pressing on the vessels. 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. A system of valves ensure one way flow.

10. Lymph Vessels 2 main vessels 2 main vessels 1. Thoracic duct on left side of body 2. 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. These ducts empty lymph into the bloodstream at the subclavian veins located near the collar bones at the shoulders.

11. Lymph Nodes Small swellings found along lymph vessels. Small swellings found along lymph vessels. Contain large no. of white blood cells with many channels the lymph can flow through. 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. Formed in clusters, which form glands i.e. Tonsils, adenoids, neck, armpits, thymus, spleen & groin.

12. Lymph Nodes They fight infection in 2 ways They fight infection in 2 ways 1. They filter bacteria 2. 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 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 If lymph vessel get blocked, swelling occurs

14. Function of Lymphatic System To collect tissue fluid & return it to the blood. 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 absorb & transport fats in the digestive system. Lymph found in lacteals (villi in small intestine) To help with hearing & balance in the ear To help with hearing & balance in the ear To defend the body against infection 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