1. The Body’s Defenses - Antibodies and the Lymphatic System

2. Learning Outcomes C6 describe the components of blood explain the roles of antigens and antibodies C7 describe the inter-relationships of the structures of the lymphatic system describe the functions of the lymphatic system q identify and give functions of lymph capillaries, veins, and nodes

3. Antibodies and Antigens Antigens are foreign substances that are recognized by the immune system They are usually proteins or polysaccharides (such as those found on cell membranes or the outer coat of a virus)

4. Antibodies are proteins produced by lymphocytes, to react with a specific antigen

5. Antibody Structure Contains 4 polypeptide chains - 2 heavy and 2 light chains Has specific sites that recognizes and binds to its particular antigen (variable region) Antibody structure

6. Antibody production B-lymphocyte recognizes a foreign antigen B cell is activated to divide rapidly B cells in plasma produce and release antibodies

7. Antibody Function Bind to antigens of invading cells causing them to clump together Phagocytic w.b.c’s (macrophages) then destroy them Memory B-cells remain in the bloodstream providing lasting immunity – these will reproduce quickly next time that specific antigen is encountered

9. Antibody video

10. The Lymphatic System A system closely associated with the circulatory system Consists of lymph vessels (veins and capillaries), lymph nodes, and organs including the spleen and thymus gland A one-way system, from tissues to blood Empties into the bloodstream at lymphatic ducts

11. Fig. 14.1

12. Lymph Vessels Lymph veins – similar in structures to circulatory veins; carry fluid from capillaries to ducts Lymph capillaries – found in all tissues, along with blood capillaries

13. Lymph Nodes Located along lymph vessels Contain large numbers of lymphocytes Function in fighting infection and antibody production

14. Functions of the lymphatic system: ①Immunity / fighting infection ②Absorption of glycerol and fatty acids in the lacteals ③Return of excess tissue fluid to the blood (capillary exchange)