Chapter 43 campbell’s ed 7

1. Chapter 43 campbell’sed 7 Immunity

2. 12 Describe the cells (B memory cells, B cells, T killer cells, T helper cells, mast cells, macrophages) and molecules (antigens, T cell receptors, B cell receptors, antibodies, perforin, complement and cytokines) involved in the nonspecific and specific defensive actions of the immune system, and explain why: 1) vaccines prevent illness; 2) HIV patients have lowered immunity; 3) why glands near sites of infection swell, and 4) why the immune system is capable of defending humans against such a broad spectrum of antigens

3. Nonspecific immunity versus specific immunity (1st, 2nd, 3rd level defenses) 43.2

4. The lymphatic system runs near the blood vessels, carrying lymph (waste materials from body tissues) through lymph nodes where memory lymphocytes & phagocytic cells await contact with the antigen matching their receptors.

5. 1st level defense (nonspecific): skin & muscous & tears prevents entry of foreign materials 43.6 2nd level nonspecific defense Macrophages & dendriditic cells ingest invaders and debris Histamines released by mast cells at injuries make epithelia of capillaries leaky & increase temperatures. Phagocytic cells move into the tissue & begin rapid phagocytosis of invaders.

6. Third line of defense: Cellular, specific immunity 43.8 • B (bone) & T (thymus) lymphocytes –named for where they mature—have receptors that bind to specific antigens (substances capable of ellicting an immune response. • A free B cell receptor is called an antibody.

7. After phagocytes ingest foreign material, T helper lymphocytes that have migrated into the inflamed tissue interact with them. The phagocytic cells present the antigens to them via a receptor called MHC- class II . The T helper cell receptor recognizes its antigen only if it’s presented by the MHC-II receptor of the antigen presenting cells. 43.9, 43.10 • Any T cells that are capable of reacting with Class II MHC in utero when the developing embryo’s system should contain only “self” antigens are destroyed (apoptosis induced) in the thymus. • When this selection is faulty autoimmune disorders develop. (e.g., Msclerosis, rheumatoid arthritis, lupus)

8. Also, cytotoxic (killer T) T cells can bind directly to virally infected cells by recognizing their receptor’s antigen when presented on an MHC class I receptor on any nucleated body cell. 43.9, 43.10 Just know that its selection against the ability of T cells and B cells to be activated by MHC receptors, especially class II, during development that allows the immune system to distinguish self from nonself, as those cells are induced to enter apoptosis and eliminated from the body.

9. The reason that we can defend ourselves against virtually any antigen is that the genes for the receptor variable regions recombine in many combinations. These are the only cells (the lymphocytes) besides gametes that show genetic recombination.

10. When lymphocytes are activated by binding to their receptors, they divide to produce many clonal cells. 41.13 Some become humoral B cells (they produce so much secreted antibody—free receptor—that they die before long) and some become memory T cells. The memory T cells lodge into the lymph nodes , then divide when the antigen appears again

11. Vaccines act as a first exposure, increasing the # of memory cells stored in the lymph nodes, so the immune 43.14

12. 43.14

13. 43.15

14. 43.16

15. 43.17