Immunity PowerPoint PPT Presentation

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Smallpox Vaccine. Before vaccines, smallpox had up to 50% death ratesNow smallpox is practically eradicated. Immunity. Body's ability to resist and combat diseasesDepends on mechanisms that recognize proteins as self or nonselfAntigen Any molecule the body recognizes as nonself and provokes an

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1. Immunity Chapter 23

2. Smallpox Vaccine Before vaccines, smallpox had up to 50% death rates Now smallpox is practically eradicated

3. Immunity Body’s ability to resist and combat diseases Depends on mechanisms that recognize proteins as self or nonself Antigen Any molecule the body recognizes as nonself and provokes an immune response

4. Evolution of Defenses Innate immunity Preset responses to nonself cues Complement, phagocytes Adaptive immunity Prepares defenses to specific pathogens encountered during an individual’s lifetime Cytokines, lymphocytes

5. Adaptive and Innate Immunity

6. Three Lines of Defense Physical barriers exclude pathogens Innate immunity begins as soon as antigen is detected Adaptive immunity forms cells that fight infection and prevent later infection

7. White Blood Cells Form in bone marrow Participate in adaptive and innate responses Release cytokines and other cell-to-cell signaling molecules

8. Chemical Weapons

12. Surface Barriers Physical barriers Intact skin Mechanical barriers Mucus, cilia, flushing Chemical barriers Protective secretions, low pH, lysozyme

13. Cilia in Airways

14. Bacterial Invaders

16. Innate Immune Response Phagocytosis Complement Fever Acute inflammation

17. Complement Many types of circulating proteins Activated by binding to antigen Triggers reactions that activate more complement Attract phagocytic cells

18. Membrane Attack Complexes

20. Acute Inflammation Nonspecific response to foreign invasion, tissue damage Destroys invaders, removes debris Symptoms are redness, swelling, warmth, and pain

21. Inflammation Mast cells release histamine Capillaries dilate and leak Complement proteins attack bacteria White cells attack invaders and clean up

23. Fever Temperature up to 39°C (102°F) Enhances immunity, increases rates of enzyme and phagocyte activity Accelerates tissue repair

24. Features of Adaptive Immunity Self/nonself recognition Specificity Diversity Memory

25. Antigens “Nonself” markers on foreign agents and altered body cells such as tumors Trigger division of B and T cells

26. Memory and Effector Cells When a B or T cell is stimulated to divide, it produces 2 cell types Memory cells: set aside for future use Effector cells: engage and destroy the current threat

27. Key Components of Immune Response MHC markers Antigen-presenting cells T cells B cells Natural killer (NK) cells

28. Formation of Antigen–MHC Complex

31. Antigen Interception

34. Antigen Receptors Antibodies Synthesized by B cells Bind to one specific antigen Mark pathogen for destruction by phagocytes and complement proteins

35. Antibody Structure Consists of four polypeptide chains Parts of each chain are variable; provide antigen specificity

39. Immunoglobins (Igs) Five classes of antibodies IgG IgA IgE IgM IgD

41. Antibody-Mediated Immune Response B cell responds to one particular extracellular pathogen or toxin Activated B cell forms clones that differentiate into effector and memory cells Effector B cells secrete antibodies that tag antigens for destruction

42. Antibody-Mediated Response

46. Cell-Mediated Immune Response Cytotoxic T cells target altered body cells that evade antibody-mediated immune response Antigen-presenting dendritic cells activate helper T cells

48. Cell-Mediated Immune Response Helper T cells secrete cytokines Induce formation of cytotoxic T cells Proliferate NK cells Enhance macrophage activity Destroy infected or altered cells

50. Immunization Process that induces immunity Active immunization: Vaccination with antigen Long-lasting immunity Passive immunization: Purified antibody is injected Protection is short lived

51. Allergies Immune reaction to harmless proteins (allergens) IgE binds to mast cells, causing inflammatory response Histamine release causes symptoms

52. Anaphylactic Shock Life-threatening allergic reaction Caused by histamine released by many mast cells Airways constrict Blood pressure drops as fluid leaks out of capillaries

53. Autoimmune Disorders Failure of immune system to distinguish between self and nonself produces antibodies against self Graves’ disease Multiple sclerosis

54. Deficient Immune Responses Primary immune deficiencies Present from birth Secondary immune deficiencies Acquired by exposure to agent such as HIV

55. HIV Replication

57. HIV Infection HIV infects immune system cells Macrophages, dendritic cells, helper T cells T cells are killed Cytokine IL-4 is released Immune system destroys itself Secondary infections and tumors cause death

59. HIV Transmission Virus transmitted by Sex Infected mothers Shared needles Not transmitted by causal contact

60. Treatment No cure AZT and other drugs slow disease and increase life span Traditional vaccines do not work Researchers continue to work

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