1. Susan Capasso, Ed.D., CGC St. Vincent’s College Suggested Lecture Presentation Copyright © 2009 Pearson Education, Inc. Chapter 13 Body Defense Mechanisms

2. Copyright © 2009 Pearson Education, Inc. Body Defense Mechanisms  The body’s defense system targets pathogens and cancerous cells  The body has three lines of defense  The immune system distinguishes self from nonself  The immune system mounts antibody- mediated responses and cell-mediated responses

3. Copyright © 2009 Pearson Education, Inc. Body Defense Mechanisms  The cell-mediated immune response and the antibody-mediated immune response have the same steps  Immunity can be active or passive  Monoclonal antibodies are used in research, clinical diagnosis, and disease treatment  The immune system can cause problems

4. Copyright © 2009 Pearson Education, Inc. The Body’s Defense System  The body’s defense mechanisms target pathogens and cancerous cells

5. Copyright © 2009 Pearson Education, Inc. The Body Has 3 Lines of Defense  The body has three lines of defense  Nonspecific 1. Physical and chemical surface barriers 2. Internal cellular and chemical defense  Specific 3. Immune response

6. Copyright © 2009 Pearson Education, Inc. The Body Has 3 Lines of Defense Figure 13.1 First line of defense: Nonspecific physical and chemical surface barriers Second line of defense: Nonspecific internal cellular and chemical defense Third line of defense: Immune response Specific defensesNonspecific defenses If pathogen penetrates barriers If pathogen survives nonspecific internal defenses

7. Copyright © 2009 Pearson Education, Inc. Nonspecific Surface Barriers  Physical and chemical barriers  The skin  Nearly impenetrable  Waterproof  Resistant to most toxins and enzymes of invading organisms  Sweat and oil glands  Produce chemicals that slow or prevent the growth of bacteria

8. Copyright © 2009 Pearson Education, Inc. Nonspecific Surface Barriers  Physical and chemical barriers (continued)  Mucus of the respiratory and digestive tracts  Sticky and traps many microbes  The lining of the stomach  Produces hydrochloric acid and digesting enzymes that destroy pathogens

9. Copyright © 2009 Pearson Education, Inc. Nonspecific Surface Barriers  Physical and chemical barriers (continued)  Urine  Slows bacterial growth with acidity  Washes microbes from urethra  Saliva and tears  Contain lysozyme, an enzyme that kills bacteria

10. Copyright © 2009 Pearson Education, Inc. Nonspecific Surface Barriers Figure 13.2 (1 of 2)

11. Copyright © 2009 Pearson Education, Inc. Nonspecific Surface Barriers Figure 13.2 (2 of 2)

12. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses  The second line of defense  Defensive cells  Defensive proteins  Inflammation  Fever

13. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses Table 13.1

14. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses Animation—The Inflammatory Response PLAY

15. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses  Defensive cells include neutrophils and macrophages  They engulf pathogens, damaged tissue, or dead cells by the process of phagocytosis

16. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses Figure 13.3

17. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses  Eosinophils  Attack pathogens that are too large for phagocytosis, such as parasitic worms  Get close to the parasites and discharge destructive enzymes that destroy them  Natural killer (NK) cells  Search out abnormal cells, including cancerous cells, and kill them

18. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses Figure 13.4

19. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses  The body’s non-specific cellular defenses use two types of defensive proteins  Interferons  Complement system

20. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses  Before a virally–infected cell dies, it secretes small proteins called interferons that  Attract macrophages and natural killer cells  Stimulate neighboring cells to make proteins that prevent the viruses from replicating

21. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses  The complement system  A group of proteins that enhance both nonspecific and specific defense mechanisms by  Destroying pathogens  Enhancing phagocytosis  Stimulating the inflammatory response

22. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses Figure 13.5 (1 of 3)

23. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses Figure 13.5 (2 of 3)

24. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses Figure 13.5 (3 of 3)

25. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses  Inflammatory response destroys invaders and helps repair and restore damaged tissue  Redness  Heat  Swelling  Pain

26. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses Figure 13.6 (1 of 2)

27. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses Figure 13.6 (2 of 2)

28. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses  The increased blood flow to damaged tissue stimulates mast cells and basophils to release histamine  Increases blood flow by dilating blood vessels and increasing the permeability of the capillaries

29. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses  Fluid leaks from the capillaries  Causes swelling  Blood flow increases  Causes redness and warmth

30. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses  Fever  An abnormally high body temperature caused by pyrogens  Chemicals that reset the brain’s thermostat to a higher temperature  A moderately higher body temperature helps fight bacterial infections

31. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses Figure 13.7

32. Copyright © 2009 Pearson Education, Inc. Nonspecific Internal Defenses Table 13.1

33. Copyright © 2009 Pearson Education, Inc. Specific Immune Responses  The third line of defense is the immune system  Has specific responses and memory

34. Copyright © 2009 Pearson Education, Inc. Specific Immune Responses  Immune response  The body’s specific defenses  Work together in the recognition and destruction of specific pathogens  Have memory

35. Copyright © 2009 Pearson Education, Inc. The Immune System Distinguishes Self from Nonself  The body must be able to distinguish a foreign organism or molecule from self  MHC markers are found on our own cells and mark them as belonging to us

36. Copyright © 2009 Pearson Education, Inc. The Immune System Distinguishes Self from Nonself Figure 13.8

37. Copyright © 2009 Pearson Education, Inc. The Immune System  Antigens  Nonself substances that trigger an immune response  Usually large molecules, such as proteins, polysaccharides, or nucleic acids

38. Copyright © 2009 Pearson Education, Inc. The Immune System  When an antigen is detected  B lymphocytes and T lymphocytes that recognize the antigen are stimulated to divide repeatedly

39. Copyright © 2009 Pearson Education, Inc. The Immune System  Some of these cells attack and eliminate the invader  Others are stored in a state of suspended animation as a form of memory of the invader  Available to attack if there is a reoccurrence

40. Copyright © 2009 Pearson Education, Inc. Antibody-Mediated Responses  Antibody-mediated immune responses  Defend against antigens that are free in body fluids, including toxins or extracellular pathogens

41. Copyright © 2009 Pearson Education, Inc. Antibody-Mediated Responses  B cells use antibodies to neutralize the antigen

42. Copyright © 2009 Pearson Education, Inc. Antibody-Mediated Responses Figure 13.9 (1 of 3) Antigen Macrophage Helper T cell Effector helper T cell Memory helper T cell Naive B cell Naive cytotoxic T cell Antibody-mediated response Engulfed Cell divides Activates Presents antigen to identify invader and activates helper T cells Step 1: Threat Step 2: Detection Step 3: Alert Step 4: Alarm Step 7: Continued surveillance Cell-mediated response

43. Copyright © 2009 Pearson Education, Inc. Antibody-Mediated Responses Figure 13.9 (2 of 3) Effector helper T cell Naive B cell Plasma cell Antibodies Memory B cell Secretes Antibody-mediated response Memory cells remain and provide a quick response to the antigen in a future encounter Cell divides Activates Step 4: Alarm Step 7: Continued surveillance Step 6: Defense Step 5: Building specific defenses Pathogens or toxins outside of cells Targets

44. Copyright © 2009 Pearson Education, Inc. Antibody-Mediated Responses Figure 13.12 (1 of 2) Step 4: Alarm The helper T cell stimulates the B cell to begin dividing. Step 5: Building specific defenses The B cell divides and forms plasma cells and memory cells. Memory B cell B cell Helper T cell Plasma cell

45. Copyright © 2009 Pearson Education, Inc. Antibody-Mediated Responses Figure 13.12 (2 of 2) Step 5: Building specific defenses The B cell divides and forms plasma cells and memory cells. Step 6: Defense Plasma cells secrete antibodies specific for that antigen. Step 7: Continued surveillance Memory B cells remain and mount a quick response if the invader is encountered again. Memory B cells Memory B cell B cell Plasma cell Antibodies Plasma cell

46. Copyright © 2009 Pearson Education, Inc. Cell-Mediated Responses  Cell-mediated immune responses  Involve living cells  Protect against cellular threats, including body cells that have become infected and cancer cells

47. Copyright © 2009 Pearson Education, Inc. Cell-Mediated Responses Figure 13.9 (1 of 3) Antigen Macrophage Helper T cell Effector helper T cell Memory helper T cell Naive B cell Naive cytotoxic T cell Antibody-mediated response Engulfed Cell divides Activates Presents antigen to identify invader and activates helper T cells Step 1: Threat Step 2: Detection Step 3: Alert Step 4: Alarm Step 7: Continued surveillance Cell-mediated response

48. Copyright © 2009 Pearson Education, Inc. Cell-Mediated Responses Figure 13.9 (3 of 3) Effector helper T cell Effector cytotoxic T cell Memory cytotoxic T cell Naive cytotoxic T cell Memory cells remain and provide a quick response to the antigen in a future encounter Cell divides Activates Step 4: Alarm Step 7: Continued surveillance Step 6: Defense Step 5: Building specific defenses Cells infected with intracellular pathogen; cancer cells; cells of organ transplants Targets Cell-mediated response

49. Copyright © 2009 Pearson Education, Inc. Cell-Mediated Responses Figure 13.14 (1 of 2) Step 5: Building specific defenses The cytotoxic T cell divides and forms effector cytotoxic T cells and memory cytotoxic T cells. Memory cytotoxic T cell Effector cytotoxic T cell Step 4: Alarm The helper T cell stimulates a naive or memory cytotoxic T cell to begin dividing. Helper T cell Cytotoxic T cell Antigen Virus

50. Copyright © 2009 Pearson Education, Inc. Cell-Mediated Responses Figure 13.14 (2 of 2) Step 5: Building specific defenses The cytotoxic T cell divides and forms effector cytotoxic T cells and memory cytotoxic T cells. Step 6: Defense Effector cytotoxic cells cause the target cell to burst and die. In this case, the target cell is a cell infected with a virus that triggered the response. Step 7: Continued surveillance Memory cytotoxic T cells remain and mount a quick response if the invader is encountered again. Memory cytotoxic T cells Memory cytotoxic T cell Target cell Effector cytotoxic T cell Perforin T cell membrane Target cell membrane Perforin assembling into pores

51. Copyright © 2009 Pearson Education, Inc. Cell-Mediated Responses Table 13.2 (1 of 2)

52. Copyright © 2009 Pearson Education, Inc. Cell-Mediated Responses Table 13.2 (2 of 2)

53. Copyright © 2009 Pearson Education, Inc. Cell-Mediated Responses Table 13.3 (1 of 2)

54. Copyright © 2009 Pearson Education, Inc. Cell-Mediated Responses Table 13.3 (2 of 2)

55. Copyright © 2009 Pearson Education, Inc. Cell-Mediated Responses Animation—Antibody- and Cell-Mediated Immunity PLAY

56. Copyright © 2009 Pearson Education, Inc. Immune Response Steps 1. Threat  Foreign cell or molecule enters the body 2. Detection  Macrophage detects foreign cell or molecule and engulfs it

57. Copyright © 2009 Pearson Education, Inc. Immune Response Steps 3. Alert  Macrophages present antigens to helper T- cells to trigger an immune response  They are called antigen-presenting cells

58. Copyright © 2009 Pearson Education, Inc. Immune Response Steps Figure 13.10

59. Copyright © 2009 Pearson Education, Inc. Immune Response Steps 4. Helper T cells activate B cells and T cells to destroy the specific antigen  When activated, these cells divide to form clones of cells designed to eliminate a specific antigen from the body

60. Copyright © 2009 Pearson Education, Inc. Immune Response Steps Figure 13.11 (1 of 2) The selected B cell divides, producing a clone of cells all bearing receptors specific for that particular antigen. The antigen binds to the B cell with appropriate receptors. This B cell has receptors specific for this particular antigen. There is a tremendous variety of B cells. Each B cell has receptors for a different antigen on its surface. Antigen B cells B-cell receptor receptor

61. Copyright © 2009 Pearson Education, Inc. Immune Response Steps Figure 13.11 (2 of 2) Plasma cells produce antibodies specific for this particular antigen. Memory cells remain to bring about a quick response to that antigen in the future. The selected B cell divides, producing a clone of cells all bearing receptors specific for that particular antigen. Plasma cells Memory cells

62. Copyright © 2009 Pearson Education, Inc. Immune Response Steps 5. Specific defense mechanism is built  B cells form plasma cells that secrete antibodies into the bloodstream that bind to antigens  T cells form cytotoxic T cells that attack

63. Copyright © 2009 Pearson Education, Inc. Immune Response Steps Figure 13.12 (1 of 2) Step 4: Alarm The helper T cell stimulates the B cell to begin dividing. Step 5: Building specific defenses The B cell divides and forms plasma cells and memory cells. Memory B cell B cell Helper T cell Plasma cell

64. Copyright © 2009 Pearson Education, Inc. Immune Response Steps Figure 13.12 (2 of 2) Step 5: Building specific defenses The B cell divides and forms plasma cells and memory cells. Step 6: Defense Plasma cells secrete antibodies specific for that antigen. Step 7: Continued surveillance Memory B cells remain and mount a quick response if the invader is encountered again. Memory B cells Memory B cell B cell Plasma cell Antibodies Plasma cell

65. Copyright © 2009 Pearson Education, Inc. Immune Response Steps 6. Primary defense  Antibodies specific to the antigen eliminate the antigen  Cytotoxic T cells release perforins that cause cells with the antigen to burst

66. Copyright © 2009 Pearson Education, Inc. Immune Response Steps  Immunoglobulins  Five classes of antibodies, each with a special role to play in protecting against invaders  IgG  IgM  IgE  IgA  IgD

67. Copyright © 2009 Pearson Education, Inc. Immune Response Steps Figure 13.13

68. Copyright © 2009 Pearson Education, Inc. Immune Response Steps Table 13.4

69. Copyright © 2009 Pearson Education, Inc. Immune Response Steps 7. Immunological memory  Allows for a more rapid response on subsequent exposure to the antigen  Primary response may be slow as the antibody concentration rises  Secondary response is strong and swift due to the large number of specific memory cells that can respond to the antigen

70. Copyright © 2009 Pearson Education, Inc. Immune Response Steps Figure 13.15

71. Copyright © 2009 Pearson Education, Inc. Immune Response Steps 8. Suppressor T cells  Turn off the immune response when the antigens no longer pose a threat

72. Copyright © 2009 Pearson Education, Inc. Active Immunity  Active immunity  The body actively participates by producing memory B cells and T cells following exposure to an antigen  This process can also happen through vaccination  Because memory cells are produced, active immunity is relatively long lived

73. Copyright © 2009 Pearson Education, Inc. Passive Immunity  Passive immunity  Results when a person receives antibodies that were produced by another person or animal  Short lived since the recipient’s body was not stimulated to produce memory cells

74. Copyright © 2009 Pearson Education, Inc. Monoclonal Antibodies  Monoclonal antibodies  A group of identical antibodies that bind to one specific antigen  Used in research, clinical diagnosis, and disease treatment because they can help diagnose certain diseases in their early stages

75. Copyright © 2009 Pearson Education, Inc. The Immune System Can Cause Problems  Autoimmune disorders  Failure to recognize distinguish between self and nonself  Occur when the immune system attacks the body’s own cells

76. Copyright © 2009 Pearson Education, Inc. The Immune System Can Cause Problems Figure 13.16

77. Copyright © 2009 Pearson Education, Inc. Immune System Problems  Allergies  Immune responses to harmless substances called allergens  Allergens cause plasma cells to release large numbers of class IgE antibodies

78. Copyright © 2009 Pearson Education, Inc. Immune System Problems Figure 13.17

79. Copyright © 2009 Pearson Education, Inc. Immune System Problems Table 13.6

80. Copyright © 2009 Pearson Education, Inc. Immune System Problems  These IgE class antibodies bind to mast cells or basophils, causing them to release histamine  The histamine causes redness, swelling, itching, and other symptoms of an allergic response

81. Copyright © 2009 Pearson Education, Inc. Immune System Problems Figure 13.18 (1 of 2) Mast cell Plasma cell Allergen IgE antibody Granules containing histamine First exposure Step 1: The invader (allergen) enters the body. Step 2: Plasma cells produce large amounts of class IgE antibodies against the allergen. Step 3: IgE antibodies attach to mast cells, which are found in body tissues.

82. Copyright © 2009 Pearson Education, Inc. Immune System Problems Figure 13.18 (2 of 2) Subsequent (secondary) response Antigen Histamine Step 4: More of the same allergen invades the body. Step 5: The allergen combines with IgE attached to mast cells. Histamine and other chemicals are released from mast cell granules. Histamine stimulates release of large amounts of mucus. Histamine causes smooth muscle in walls of air tubules in lungs to contract. Step 6: Histamine causes blood vessels to widen and become leaky. Fluid enters the tissue, causing swelling.

83. Copyright © 2009 Pearson Education, Inc. Immune System Problems  Antihistamines are most effective in reducing the allergy symptoms

84. Copyright © 2009 Pearson Education, Inc. Immune System Problems  Allergy shots inject increasing amounts of a known allergen in an effort to desensitize the person to the offending allergens