1. THE BODY’S DEFENSE CHAPTER 43

2. Immunity Invertebrates have nonspecific systems Plants have molecular recognition of pathways to defend against pathogens; leads to destruction of infected cells Vertebrates have nonspecific and nonheritable defense systems Mammals have nonspecific, humoral and cell mediated.

3. Figure 43.4 The human lymphatic system

4. Figure 43.0 Specialized lymphocytes attacking a cancer cell

5. Figure 43.2 First-line respiratory defenses. Inside the lining of the trachea. Yellow cells are ciliated. Orange cells secrete mucus.

6. Innate immunity is present before any exposure to pathogens and is effective from the time of birth It involves nonspecific responses to pathogens Innate immunity consists of external barriers plus internal cellular and chemical defenses

7. Acquired immunity, or adaptive immunity, develops after exposure to agents such as microbes, toxins, or other foreign substances It involves a very specific response to pathogens

8. NONSPECIFIC DEFENSE Skin Mucus Secretions

9. CELLS: Nonspecific Neutrophils - engulf microbes (phagocytosis); self-destruct after destroy microbes Macrophages - can migrate into tissues and engulf microbes Esinophils - destroy parasitic worms Natural killer cells - destroy viral-infected cells

10. Figure 43.x1 Anabaena (a blue-green algae that makes a toxin, which causes cell death) phagocytosed by a human neutrophil Anabaena

11. Figure 43.3x Macrophage

12. Figure 43.3 Phagocytosis by a macrophage Bacilli Pseudopodia of macrophage

13. INFLAMMATORY RESPONSE Arterioles dilate to increase blood flow to damaged area Increased WBC in damaged area Histamine and prostaglandins released to dilate arterioles Chemokines - chemical signals for cells to follow

14. Fig. 43-8-3 PathogenSplinter Macrophage Mast cell Chemical signals Capillary Phagocytic cell Red blood cells Fluid Phagocytosis

15. SPECIFIC DEFENSE Response is to a specific microbe Antigen - foreign molecule Antibody - proteins made to attach to specific antigens

16. CELLS:Specific B lymphocytes - develop in bone marrow; differentiate into plasma cells which secrete antibodies; also make memory cells T lymphocytes - develop in thymus; activate B cells and other WBC; also make memory cells

17. Figure 43.8 The development of lymphocytes

18. Figure 43.8x B lymphocyte

19. Figure 43.6 Clonal selection

20. Primary immune response - first exposure; 10 - 17 days; make antibodies Secondary immune response - already been exposed; 2 - 7 days; memory cells make antibodies quickly

21. Figure 43.7 Immunological memory

22. TOLERANCE FOR SELF Major histocompatibility complex (MHC) on cells –Class I MHC on all nucleated cells –Class II MHC on macrophages, B cells and activated T cells –Biochemical fingerprint –As your cells develop, if fingerprint is wrong then cell death occurs

23. –MHC molecules cradle foreign antigens. They present the antigen to other cells. MHC I presents antigens to Cytotoxic T cells which kill bad cells MHC II presents antigens to Helper T cells –Cells that present antigens are called antigen presenting cells (APCs). These include macrophages and B cells.

24. Figure 43.9 The interaction of T cells with MHC molecules

25. HUMORAL VS. CELL MEDIATED IMMUNITY Humoral - B cells activated by free antigens (free bacteria, toxins, viruses) Cell mediated - depends on T cells; active against cells infected with viruses and bacteria; as well as free fungi, protozoa, and worms

26. Fig. 43-16 Humoral (antibody-mediated) immune response B cell Plasma cells Cell-mediated immune response Key Stimulates Gives rise to + + + + + + + Memory B cells Antigen (1st exposure) Engulfed by Antigen- presenting cell Memory Helper T cells Helper T cellCytotoxic T cell Memory Cytotoxic T cells Active Cytotoxic T cells Antigen (2nd exposure) Secreted antibodies Defend against extracellular pathogens by binding to antigens, thereby neutralizing pathogens or making them better targets for phagocytes and complement proteins. Defend against intracellular pathogens and cancer by binding to and lysing the infected cells or cancer cells. + ++

27. Immune System Players Antigen presenting cells (APC) include B cells and macrophages Present antigen on class II MHC T helper cell (T h ) binds to MHC II with antigen CD4 on T h cell holds APC cell and T h cell together

28. T h then activates T cytotoxic cells T cytotoxic cells can then lyse infected cells

29. Figure 43.11 The central role of helper T cells: a closer look

30. Figure 43.12a The functioning of cytotoxic T cells

31. Figure 43.12b A cytotoxic T cell has lysed a cancer cell

32. ANTIBODY PRODUCTION T-dependent antigens - B cell must be activated by T h cell; most protein antigens T-independent antigens - directly stimulate B cells to make antibodies; mostly polysaccharide antigens

33. Figure 43.13 Humoral response to a T-dependent antigen (Layer 3)

34. ANITBODY MEDIATED DISPOSAL OF ANITGEN Opsonization - many antibodies bound to antigen enhance macrophage phagocytosis Agglutination - antibodies attach to many antigens; clumping them together to enhance phagocytosis

35. Figure 43.16 Effector mechanisms of humoral immunity

36. ACTIVE IMMUNITY Depends on response of infected person’s immune system May be artificially induced by vaccinations

37. Figure 43.x2 Vaccination

38. PASSIVE IMMUNITY Antibodies transferred from one individual to another Some antibodies can move across placenta to baby in pregnant women Nursing

39. HEALTH AND DISEASE Review ABO blood types and Rh MHC causes tissue and organ rejections In bone marrow transplants, donated marrow (with WBC) will react against recipient

40. Allergies - overproduction of certain antibodies causes histamine to be released –Runny nose –Teary eyes –Smooth muscle contractions = hard breathing

41. Figure 43.x4 Alternaria spores, a cause of allergies in humans

42. Anaphylactic shock - life- threatening reaction; abrupt dilation of arteries causes serious drop in blood pressure Autoimmune diseases - attack own body –Lupus, rheumatoid arthritis, MS Immunodeficiency Diseases –Severe combined immunodeficiency (SCID), Hodgkin’s

43. Figure 43.x3 X-ray of hands with arthritis

44. AIDS - acquired immunodeficiency syndrome –Two major strain: HIV I and HIV II –Bind to CD4 and therefore T h cells –Insert its RNA and reverse transcriptase makes viral DNA that is inserted into host’s DNA

45. –Exists as provirus so antibodies can’t get rid of it easily –Mutates often –May cause T h cell death –HIV positive = presence of HIV antibodies

46. Figure 43.19 A T cell infected with HIV

47. Figure 43.19x1 HIV on a lymphocyte, detail

48. Figure 43.20 The stages of HIV infection

49. Figure 43.x5 AIDS posters