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Immune System


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Immune System

  1. 1. Immune System
  2. 2. Pathogen A pathogen is an organism or virus that causes a disease. <ul><li>Type Pathogen Disease </li></ul><ul><li>Virus Adeno Common </li></ul><ul><li>Cold   </li></ul>Type Pathogen Disease Bacteria  Salmonella  Food poisoning
  3. 3. <ul><li>Type   Pathogen   Disease     </li></ul><ul><li>Fungi  Epidermophyta   Tinea faciei floccosum (ringworm)  </li></ul>Protozoa  Plasmodium   Malar falciparum
  4. 4. Type   Pathogen   Disease <ul><li>Flatworm   Fasciola hepatica Fascioliasis </li></ul><ul><li>(fluke) (sheep fluke)  </li></ul><ul><li>Roundworms   Toxocara canis   Trichuriasis </li></ul><ul><li>(Nematodes) </li></ul>
  5. 5. Methods of disease transmission <ul><li>Water </li></ul><ul><li>Food </li></ul><ul><li>Air borne(aerosol droplet) </li></ul><ul><li>Touch </li></ul><ul><li>Sexual transmission </li></ul><ul><li>Vectors (animals) </li></ul>
  6. 6. Human Bacterial Disease Salmonellosis <ul><li>Salmonella enteritidis is the disease causing agent </li></ul><ul><li>Transmission: Through poultry and their eggs, especially when uncooked (e.g. mayonnaise and ice cream), or lightly-cooked (e.g. meringue and soft-boiled eggs); or through un-pasteurised milk. Other sources are contamination of foods and water by human or household pet faeces </li></ul><ul><li>Effects: The bacteria colonise small intestine and remain there producing exotoxins Sudden signs 15-48 h after eating infected food. This is much faster than typhoid because the bacteria remain in the gut. Symptoms include moderate diarrhoea, vomiting, abdominal pain, mild fever and headache. Recovery usually in 2-3 days. </li></ul>
  7. 7. Antibiotics Effectiveness <ul><li>Antibiotics block specific metabolic pathways found in bacteria, but not in eukaryotic cells. Some antibiotics are cidal , which means they kill the microbes, while others are static , which means they stop further growth, but don't kill existing cells. Both are useful medically, because if the growth of an infective pathogen is stopped, the body's immune system will be able to kill it. </li></ul>
  8. 8. These graphs show how the two kinds of drug affect bacterial growth curves. <ul><li>Bacteria, as prokaryotes, have many unique features not present in eukaryotes, so antibiotics can be selectively toxic by targeting such features as the bacterial cell wall </li></ul>
  9. 9. Figure 43.4 The human lymphatic system
  10. 10. Defense Mechanisms: <ul><li>Defense can be non-specific or specific (B cells and T cells) </li></ul><ul><li>Non-specific mechanisms provide a general barrier to infection and is the first line of defense. </li></ul>
  11. 11. Figure 43.1 An overview of the body's defenses
  12. 12. Non-specific (NS) <ul><li>Skin is a physical barrier reinforced by oil and sweat secretions with a low (acidic pH). </li></ul><ul><li>Mucous membranes contain lysozyme ; an enzyme that attacks bacterial cell walls. </li></ul>
  13. 13. <ul><li>Phagocytosis (white blood cells) </li></ul><ul><li>Neutrophils attack microbes in infected tissue. Only live a few days. </li></ul><ul><li>Monocytes develop into longer-lived macrophages. Have long pseudopods and are amoeboid in shape. </li></ul><ul><li>Eosinophils attack larger parasitic invaders. They attach to the invader and secrete digestive enzymes to destroy it . </li></ul><ul><li>NK (natural killer) cells destroy virus-infected body cells and abnormal pre-cancerous cells. Attack the membrane of these cells and cause the cell to burst . </li></ul>
  14. 14. Figure 43.2 First-line respiratory defenses
  15. 15. Figure 43.3 Phagocytosis by a macrophage
  16. 16. Figure 43.3x Macrophage
  17. 17. Figure 43.x1 Anabaena phagocytosed by a human neutrophil
  18. 18. 2 nd line of defense : Inflammatory response <ul><li>Basophil cells in the blood and mast cells in connective tissue release the molecule histamine . </li></ul><ul><li>Inflammation increases blood flow, fevers, redness. </li></ul>
  19. 19. Figure 43.5 A simplified view of the inflammatory response
  20. 20. Figure 43.5 A simplified view of the inflammatory response
  21. 21. Figure 43.1 An overview of the body's defenses
  22. 22. Lymphocytes <ul><li>Provide specific immunity for the body. </li></ul><ul><li>There are 2 types of lymphocytes </li></ul><ul><li>1. B cells </li></ul><ul><li>2. T cells </li></ul><ul><li>They circulate through the blood and are concentrated in the lymph nodes and spleen. </li></ul>Specific Defense 3 rd line of defense
  23. 23. Figure 43.8 The development of lymphocytes
  24. 24. Antigen <ul><li>An antigen is any molecule that is foreign such as bacteria, viruses, protozoans, worms, etc. </li></ul>
  25. 25. Activation of B cells <ul><li>Constructed in the bone marrow </li></ul><ul><li>B cells secrete proteins called antibodies that seek out antigens. </li></ul><ul><li>B Cell defense deals with invaders circulating in the blood or plasma, not inside cells. </li></ul>
  26. 26. Figure 43.8x B lymphocyte
  27. 27. <ul><li>Plasma cells synthesis antibodies </li></ul><ul><li>B) The antibody binds them to other antigen </li></ul><ul><li>C) Makes it easier for the Antigen (A) to be engulf by phagocytic      </li></ul>
  28. 28. <ul><li>B cells can build up a “memory” to increase response time of a future attack of the same antigen. </li></ul><ul><li>Antibody molecules are complex, consisting of two heavy chains and two light chains. </li></ul><ul><li>These chains are held together by disulfide bridges (bonds). </li></ul>
  29. 29. Figure 43.15a,b The structure of a typical antibody molecule
  30. 30. Figure 43.16 Effector mechanisms
  31. 31. Antibody Production
  32. 32. Antibody Production <ul><li>(a) There are many different lymphocytes. </li></ul><ul><li>(b) The antigen infects and is presented to the lymphocytes </li></ul><ul><li>(c) The lymphocyte with a surface epitope complementary to the antigen is selected. </li></ul><ul><li>(d) The Lymphocyte clones to produce many plasma cells. This occurs in the lymph nodes. </li></ul><ul><li>(e) The clone of plasma cells </li></ul><ul><li>(f) The gene for the antibody is expressed and secreted into the plasma and tissue fluid. </li></ul><ul><li>(g) The antibody circulated in body fluids destroying the infectious antigen </li></ul>
  33. 33. Monoclonal Antibodies
  34. 35. T cells <ul><li>Mature in the thymus. </li></ul><ul><li>Attack cells that are infected or B cells that have destroyed an invader. </li></ul><ul><li>Tries to distinguish “self” from “non-self”. </li></ul><ul><li>Cytotoxic “killer” t cells can destroy cancer cells. </li></ul>
  35. 36. <ul><li>• Tk Cytotoxic cells are able to find and then destroy cells infected with a virus or a cancerous cell . </li></ul><ul><li>• Probe the surface of cells looking for 'self' and leave alone. </li></ul><ul><li>• Cancer cells and virus infected cells carry antigen their plasma membrane. </li></ul><ul><li>• Tk Cytotoxic cells detect this and destroy the infected cell. </li></ul><ul><li>• This also destroy the virus or cancer cell reducing or preventing the spread of infection within the tissue. </li></ul>
  36. 37. Figure 43.9 The interaction of T cells with MHC molecules
  37. 38. Figure 43.11 The central role of helper T cells: a closer look
  38. 39. Figure 43.12a The functioning of cytotoxic T cells
  39. 40. Figure 43.13 Humoral response to a T-dependent antigen (Layer 1)
  40. 41. Figure 43.13 Humoral response to a T-dependent antigen (Layer 2)
  41. 42. Figure 43.13 Humoral response to a T-dependent antigen (Layer 3)
  42. 43. Activation of a immune response <ul><li>Antigen enters organism </li></ul><ul><li>Macrophages engulf antigen using MHC proteins </li></ul><ul><li>Marophages display antigens to Helper T Cell causing them to become active, signaling B Cell. </li></ul><ul><li>Activated B Cell be begin CLONING plasma cell. </li></ul><ul><li>Plasma cell production leads to a increase production of antibodies designed for the antigen </li></ul>
  43. 44. Figure 43.10 An overview of the immune responses (Layer 1)
  44. 45. Figure 43.10 An overview of the immune responses (Layer 2)
  45. 46. Figure 43.10 An overview of the immune responses (Layer 3)
  46. 47. Figure 43.10 An overview of the immune responses (Layer 4)
  47. 48. Types of Immunity <ul><li>1. Active Immunity : Immunity due to the production of antibodies by the organism itself. </li></ul><ul><li>2. Passive Immunity : due to the acquisition of antibodies from another organism (such as mother to child) </li></ul>
  48. 49. Types of Immunity <ul><li>3. Natural Immunity : Immunity due to a previous infection. </li></ul><ul><li>4. Artificial Immunity : due to inoculation by a vaccine. </li></ul>
  49. 50. <ul><li>Weakened forms of the antigen are exposed to the individual triggering an immune response and the formation of memory cells </li></ul><ul><li>A second exposure can through another vaccination or exposure from person to person contact can boost production of additional antibodies </li></ul>
  50. 51. Vaccination <ul><li>Benefis </li></ul><ul><li>End to some diseases </li></ul><ul><li>(small pox) </li></ul><ul><li>Long term effects my some diseases maybe reduced </li></ul><ul><li>Dangers </li></ul><ul><li>Excess exposure to </li></ul><ul><li>vaccinations reduces </li></ul><ul><li>effectiveness of immune </li></ul><ul><li>system </li></ul><ul><li>Side Effects, long term disability (whooping cough) </li></ul><ul><li>If antibodies are not monitored later in life, adults may catch a more sever version of the disease (measles, mumps) </li></ul>
  51. 52. HIV <ul><li>HIV is the retrovirus responsible for causing AIDS. </li></ul><ul><li>AIDS is an autoimmune disease. </li></ul><ul><li>Causes a reduction in the number of active lymphocytes (B cells and T cells). </li></ul><ul><li>Causes a loss in ability to produce antibodies. </li></ul>
  52. 53. Figure 43.19 A T cell infected with HIV HIV attaches to T cells and infects them.
  53. 54. <ul><li>Involves the transfer of body fluids </li></ul><ul><ul><ul><ul><li>Through cuts </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Needles </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Across the placenta/mothers milk </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Blood transfusion </li></ul></ul></ul></ul>Social Implications Transmission <ul><li>Family grief </li></ul><ul><li>Lost wages </li></ul><ul><li>Stigmatization </li></ul>
  54. 55. Figure 43.19x1 HIV on a lymphocyte, detail
  55. 56. Figure 43.19x2 HIV budding
  56. 57. Figure 43.19x2a T cell infected with HIV
  57. 58. Figure 43.19x2b Detail of HIV on lymphocyte
  58. 59. Figure 43.20 The stages of HIV infection
  59. 60. Loca- tion Reported AIDS Cases to Date since 1981 AIDS Deaths to Date (since 1981) Estimated Persons Living with AIDS Estimated Persons Living with HIV/AIDS Estimated New Infections per Year World 2,201,461 21,800,000 ??? Millions? 42,000,000 5,000,000 US 816,149 467,910 362,827 800,000-900,000 40,000 California 129,224 77,658 51,566 107,837-124,305 6,788-8,988 San Fransc 28,370 19,263 9,107 17,838 in San Frans. 1,084