1. Immune System Chapter 21

3. Nonspecific Defenses Species resistance - docking sites on cells only allow certain pathogens to attach. Ex: you can’t get: –Tobacco mosaic virus –Dutch elm disease –Distemper

4. Mechanical & Chemical Barriers –1 st Line of Defense Skin and mucous membranes Stomach - HCl Tears - lysozyme Hair

5. –2 nd Line of Defense Inflammation – chemotactic proteins Phagocytosis – macrophages and neutrophils

6. –Natural Killer Cells – tumor cells and cells with viral infections –Interferon – anti-viral proteins –Complement Proteins – causes lysis of antigen –Fever

7. White blood cells (WBC) are released Monocytes, macrophages, neutrophils, eosinophils, natural killer cells a.Blood vessels expand near the wound or entry. b.Swelling occurs (caused by histamine) which increases body temperature to kill off pathogens c.Basophils released 2 nd line of defense: Inflammatory Process

8. Specific Cellular Defenses Overview of Immune Response –Humoral Immunity Provided by antibodies Produced by lymphocytes Bind to bacteria and free floating viruses

9. –Cell Mediated Immunity Special lymphocytes direct the attack of infected cells Attack cancer cells, parasites, transplants Release chemicals to mediate OR stimulate other parts of the immune system

10. –Antigens Large molecules that interact and respond to cells and immune chemicals –Antibodies Native antigens; immunoglobulins

11. Humoral Immunity (B-Cell Immunity) Produced in the bone marrow Produce antibodies Stimulated by antigens and/or lymphokines

12. 2 types of B cells –Plasma cells – make antibodies (2000/sec) and memory cells –Memory cells – remain for a lifetime to produce more antibodies if antigen returns

13. Antibodies –5 classes –IgD – attached to B cells; act as a receptor sites –IgM – RBC, food and bacterial markers; stimulates complement proteins; agglutinating agent

14. –IgG – main antibody; tissue marker, virus, bacteria and toxin antibody –IgA – found in milk, tears, urine, sweat; prevents attachment of pathogens to epithelial tissues –IgE – associated with allergies; cause release of histamine

16. Responsible for 1 o and 2 o immune response –1 o - initial exposure to antigen, plasma cells produce antibodies; lag time –2 o – subsequent exposure to previous antigen; produce 1000’s of antibodies within hours

17. –Types of Antibody Immunity Acquired Immunity –Active artificial – vaccine of the antigen (measles); requires boosters –Passive artificial – vaccine of antibodies from another infected animal (rabies)

18. Natural Immunity –Active natural – get the disease; lifetime immunity –Passive natural – mother’s antibodies are passed to fetus prior to birth; short-term

19. Cell-Mediated Immunity –T cells Originate and mature in the thymus Must become “tolerant” to body’s own proteins so as not to react to them Can only recognize an “antigen” when it is bound to another immune cell

20. Secrete “lymphokines” to stimulate cloning of other immune cells 4 types: –Cytotoxic (killer) T cells – secrete “perforin” which lyses target cells –Helper T cells – direct cloning of other T & B cells through secretion of lymphokines

21. –Suppressor T cells – dampens activity of killer & helper cells –Delayed hypersensitivity T cells – play role in allergies and chronic inflammation

22. Organ Transplants 4 Types of transplants (grafts) –Autografts – self to self; always successful –Isografts – identical twins; always successful

23. –Allografts – same species; used most often; complications due to tissue typing –Xenografts – different species; rarely successful

24. Following transplantation –Anti-inflammatory drugs –Cytotoxic drugs –Radiation –Cyclosporin to suppress production of interleukins, Helper T and Cytotoxic T cells without stopping production of already sensitized B cells

25. Rejection –Early – inadequate blood supply to graft –Late – burst of unexplained antibodies

26. Homeostatic Imbalances Immunodeficiencies Autoimmunity

27. Hypersensitivities – body responds to a harmless antigen –Immediate hypersensitivity- within minutes –Cytotoxic hypersensitivity – transfusion reactions

28. –Immune-complex hypersensitivity – strep, malaria, chronic viral infections; cause rashes, swollen lymph nodes –Delayed hypersensitivity – poison ivy, cosmetics