Lymphatic System

1. Lymphatic System

2. Lymphatic System • Consists of: • Lymphatic vessels • Lymphatic tissues • Lymphoid organs • Lymph which consists of • Interstitial fluid • Lymphocytes • Macrophages

3. Lymphatic System

5. Functions of the Lymphatic System • Production, maintenance, distribution of lymphocytes • Lymphocytes are infection fighting WBC • Maintain normal blood volume • Return of water and solutes that leak out into the interstitial fluid to the circulatory system • Plasma protein recycling • Alternate route for transport of hormones, nutrients, and waste products

6. Lymphoid Structures • Primary lymphoid structures • Structures that produces lymphocytes • Bone marrow, thymus, spleen • Secondary lymphoid structures • Places where the immune response begins • Lymph nodes, tonsils

7. Lymphatic capillaries

9. Lymphatic Vessels • Carry lymph from peripheral tissue to venous system • Like veins, they go from small to large and have valves • System has no pump, and is unidirectional • Vessel system goes as follows: • Lymph capillaries • Lymph collecting vessels • Lymph nodes • Lymph trunks • Lymph ducts

10. Lymph Ducts • Lymph trunks empty into the lymph ducts • Lumbar trunk • Intestinal trunk • Bronchomediastinal trunk • Subclavian trunk • Jugular trunk • Two major lymph ducts • Thoracic duct • Right lymphatic duct • Ducts return lymph to venous circulation at the L and R subclavian veins

12. Lymph and Disease • Any materials in the interstitial fluid can be picked up by the lymphatic system • Pathogens in the tissues can get into the lymph and travel throughout the body • Lymph nodes “inspect” the lymph for foreign material • Swollen or tender nodes can indicate an immune response to pathogens in the lymph

13. This looks bad! • Elephantiasis • Blockage of the lymphatic return system by a worm • Causes gross swelling(edema) of the tissue due to fluid build up • Can be cured • Don’t worry the worm doesn’t live in San Diego

14. Lymphocytes • Lymphocytes are types of WBC • Responsible for specific immunity to pathogens • Two major types of lymphocytes • B cells: produce antibody for humoral immune response • T cells: cell-mediated immunity • T helper cells, cytotoxic T cells, and suppressor T cells are the major types

15. Origin of B cells and T cells • Both types of cells originate in the bone marrow • B cells mature in the bone marrow hence the name B cells • T cells originate in the bone marrow but move to the thymus gland to mature, hence the name T cells • Both T cells and B cells are found in various lymphatic tissues

16. Lymphoid tissue and organs • Tonsils • Lymph nodes • Spleen • Thymus

17. Tonsils • Lymphoid nodules found in the pharynx • Aggregation of lymphocytes that remove pathogen from air or food • Usually 5 tonsils • Single pharyngeal tonsil (adenoids) • Pair of palatine tonsils • Pair of lingual tonsils

19. Lymph Node

20. Lymph Node

25. Spleen • Soft, pulpy organ wedged between the stomach, diaphragm and left kidney • The cellular component of the spleen is called the pulp • Red pulp • Mostly RBC • White pulp • Lymphatic nodules