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THE BODY’S DEFENSE

THE BODY’S DEFENSE. CHAPTER 43. Figure 43.4 The human lymphatic system. Figure 43.0 Specialized lymphocytes attacking a cancer cell. Figure 43.2 First-line respiratory defenses. Inside the lining of the trachea. Yellow cells are ciliated. Orange cells secrete mucus.

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THE BODY’S DEFENSE

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  1. THE BODY’S DEFENSE CHAPTER 43

  2. Figure 43.4 The human lymphatic system

  3. Figure 43.0 Specialized lymphocytes attacking a cancer cell

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

  5. 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

  6. 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

  7. NONSPECIFIC DEFENSE • Skin • Mucus • Secretions

  8. 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

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

  10. Figure 43.3x Macrophage

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

  12. 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

  13. Fig. 43-8-3 Pathogen Splinter Chemical signals Macrophage Fluid Mast cell Capillary Phagocytosis Red blood cells Phagocytic cell

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

  15. 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

  16. Figure 43.8 The development of lymphocytes

  17. Figure 43.8x B lymphocyte

  18. Figure 43.6 Clonal selection

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

  20. Figure 43.7 Immunological memory

  21. 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

  22. 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.

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

  24. 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

  25. Fig. 43-16 Humoral (antibody-mediated) immune response Cell-mediated immune response Key Antigen (1st exposure) Stimulates Gives rise to + Engulfed by Antigen- presenting cell + + + B cell Helper T cell Cytotoxic T cell + + Memory Helper T cells + + + Antigen (2nd exposure) Memory Cytotoxic T cells Active Cytotoxic T cells + Plasma cells Memory B cells 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.

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

  27. Th then activates T cytotoxic cells • T cytotoxic cells can then lyse infected cells

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

  29. Figure 43.12a The functioning of cytotoxic T cells

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

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

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

  33. 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

  34. Figure 43.16 Effector mechanisms of humoral immunity

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

  36. Figure 43.x2 Vaccination

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

  38. 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

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

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

  41. 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

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

  43. AIDS - acquired immunodeficiency syndrome • Two major strain: HIV I and HIV II • Bind to CD4 and therefore Th cells • Insert its RNA and reverse transcriptase makes viral DNA that is inserted into host’s DNA

  44. Exists as provirus so antibodies can’t get rid of it easily • Mutates often • May cause Th cell death • HIV positive = presence of HIV antibodies

  45. Figure 43.19 A T cell infected with HIV

  46. Figure 43.19x1 HIV on a lymphocyte, detail

  47. Figure 43.20 The stages of HIV infection

  48. Figure 43.x5 AIDS posters

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