micro ch 17

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wvuong
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67923
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micro ch 17
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2011-02-21 16:30:13
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exam 2
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  1. invasiveness
    ability of a parasite to penetrate tissues and cause structural damage; type of virulence factor
  2. toxins
    microbial poisons that affect the establishment and course of disease by increasing microbe's virulence
  3. two types of toxins:
    exotoxins and endotoxins
  4. exototoxins are..
    • protein molecules, manufactured mainly G+ bacteria, produced by botulism organism, clostridium botulinum.
    • inhibits release of neurotransmitter called acetylocholine at junction where nerve cells meet muscle cells; inhibition leads to paralysis
  5. body's response to exotoxins?
    special antibodies called antitoxins
  6. antitoxin...
    combines with toxin and neutralizes it
  7. toxoid
    an altered toxin, where chemical agent used to alter the toxi nand destroy its toxicity
  8. toxoid molecules used as?
    vaccines to protect against diphtheria and tetanus
  9. endotoxins..
    part of cell wall of G- bacteria and released only on disintegration of cell
  10. endotoxins manifest itself by...
    certain signs and symtoms such as increased body temp, body weakness and aches, and general malaise
  11. endotoxin shock
    damage to circulatory system and shock occur
  12. nonspecific resistance to disease, affected by these determinants..
    nutrtion, fatigue, age, sex, and climate
  13. species immunity-
    form of nonspecific resistance that means the diseases affecting one species will not affect another
  14. keratin is..
    poor source of carbon for microbes
  15. the skins have these...
    sweat and fatty acids in sebum that contain antimicrobial agents and low water content make its veritable desert
  16. Metchnikoff termed...
    phagocytosis
  17. phagocytosis-
    form of nonspecific resistantce in body
  18. cells involved in phagocytosis called?
    phagocytes are large cells that originate in bone marrow, circulte in bloodstream, then leave circulation, and develop in tissues
  19. highly specialized phagocytes
    • macrophages;
    • found in spleen, bone marrow, lymph nodes, and brain
  20. what happens when a macrophage encounter a microbe?
    • encloses microbes with cell membrane, infolds membrane to form phagocytic vesicle or phagosome.
    • then pinches off and fuse with lysosome
    • -bacterium disintegrates thru activity of lysosomal enzymes
  21. nonspecific defensive response that occurs when irritant such as microbe is present
    inflammation
  22. inflammation-
    irritant sets to motion and limits extent of injury [dilation of blood vessels increases flow of blood at site of irritation]
  23. signs of inflammation.
    • rubor [red color from blood accumulation]
    • calor [warmth from heat of blood]
    • tumor [swelling]
    • dolor [pain from injury to local nerves]
  24. Antigens-
    • chemical substances capable of stimulating immune system and provoking immune response
    • -large, complex molecules, not normally found in body and refer to 'nonself'
    • -milk proteins, bee venom proteins, hemoglobin molecules, baccterial toxins, and chemical substance found in microbial flagella, pili, and cytoplasm
  25. most common antigens=
    • proteins and polysaccharides,
    • lipids and nucleic acids can be antigens
  26. proteins are potent antigens
    cuz amino acids represent a great array of bilding blocks, allowing for huge variety of combinations
  27. antigens easily phagocytized by..
    • macrophages
    • antigen itself doesnt stimulate immune system, but by antigen molecule called antigenic determinant (or epitope)
  28. antigenic determinant
    contains 6-8 amino acid molecules or monosaccharide units
  29. lymphocytes
    • cornerstones of immune system
    • -distributed thru-out body and comprise organs of lymphoid system, includes lymph nodes, spleen, tonsils, and adenoids
    • -small cells, each with large nucleus
  30. two types of lymphocytes
    • -B lymphocytes (B cells)
    • -T lymphocytes (T cells)
  31. B cells responsible for
    antibody-mediated immunity
  32. T cells are responsible for
    cell-mediated immunity
  33. lymphocytes origination.
    • from stem cells [primitive cells in yolk sac and bone marrow]
    • stem cells develop to lymphopoietic cells, which take on two paths
  34. whats the two path that lymphopoietic cell will take?
    • 1. move to thymus, then modified by addition of suface receptor proteins or destroyed. destoryed ones are one's that respond to self. modified lympopoietic cells emerge as T cells
    • 2. B cells . mature in site that has not been determined with certainty in humans. in embryonic chick, site idenitified as bursa of Fabricius
  35. B cells mature...
    with surface receptor proteins on membranes and become immunocompetent. move thru circulatory system to coloize organs of lymphoid system, where join T cells
  36. surface receptor proteins
    enable B cells and T cells to recognize specific antigenic determinant and bind to it
  37. surface recptor proteins in B cells? T cells?
    • B cells- antibody molecule, called IgD
    • T cell - composed of two chains linked one another
  38. B cell and T cell oversees...
    • B cell - bacteria and viruses
    • T-cell - fungi and protozoa
  39. cell-mediated immunity CMI
    body's ability to resist infection thru activity of T-lymphocyte recognition of antigen peptides presented on macophages and dendritic cells and on infected cells
  40. major histocompatibility proteins (MHC proteins)
    macrophage have these that must match with MHC receptors on surface of T-cell
  41. match up with MHC completed, ...
    inactived T-cells assume to activated form, cytotoxic T cell. transition acquires help of helper T cell . antigenic determinants and MHC protein must match with helper T cell. (CD4 receptor)
  42. helpter T cell after attachment...
    multiplies and clones and secretes highly charged proteins aka lymphokines[aka cytokines]
  43. lymphokines
    stimulate cytotoxic T cells to enlarge and divide, yeild host of cells capable of killing infected cells
  44. Cytotoxic T cells travels..
    leave lymphoid tissues to lymph and blood vessels seeking infect individuals, finds them and releases number of active substances, include toxic protein called perforin
  45. perforin -
    toxic protein inserts to membrane of microbes or infecte cell and dissolves it.
  46. cytotoxic T cell releases
    lymphokines, which are glycoprotein molecules used to enhance defensive capabilities of body
  47. transfer factor,
    third lymphokine that mobilizes other T cells in area and encourages their conversion to cytotoxic cells
  48. memory T cells
    type of T cells form in lymphoid tissues that provide resistance to the event which the pathogen reenters body in future.
  49. antibody-mediated immunity AMI
    aka humoral immune response. immune reaction of producing antibodies directed against antigens in body fluids
  50. AMI.
    antibodies react with toxin molecules in bloodstream, also with microbial antigens and wiht viruses in body fluid
  51. once B cells activated,
    multiply rapidly, developing to plasma cells
  52. plama cells are...
    large, complex cells having no suface protein receptors, sole purpose is to produce antibodies. and antibody molecules fill the blood, lymph, saliva, sweat, and all body secretions
  53. some B cells do not become plasma cells but...
    memory B cells
  54. memory B cells-
    remain in lymphoid tissues for years, should antigens reenter body, memory cells will revert to plasma cellsa nd produce antibodies wihout delay
  55. structure of antibodies.
    consists of 4 polypeptide chains: 2 identical heavy (H) chains and two identical light (L) chains. joined together by chemical linkages to form Y-shaped
  56. polypeptide chain -
    • both have constant and variable regions
    • constant regions - amino acids identical among differ types of antibodies
    • variable regions - amino acids differ of antibody types
  57. somatic recombination
    • -Susumu Tonegawa
    • -incalculable number of gene combinations acct for variety of antibody moelcules body produces
  58. 5 differ types of antibodies.
    • - IgM,
    • - IgG
    • - IgA,
    • - IgE,
    • -IgD
  59. IgM
    first type of antibody to appear in circulatory system after B cell stimulation, the largest
  60. IgG
    • gamma globulin
    • major circulating one,
    • appears about 24-48 hours after antigenic stimulationg and cont the antigen-antibody interaction begun by igM
    • provides long0term resistance to disease
    • maternal antibody that crosses placenta and renders immunity to child
  61. IgA
    • serum IgA
    • -second form of IgA accumulates in body secretions aka secretory IgA
    • -provides resistance in respiratory & gastrointestinal tracts, by inhit attachment of parasites to tissues
    • -located in tears and saliva in colostrum, first milk secreted by mothers
    • -consumed by child, provides resistance to gastrointestinal disordres
  62. IgE
    in allergic reactions by sensitizing cells to certain antigens
  63. IgD
    • membrane antibody - cell surface receptor on B cells
    • functions and significance - unclear
  64. antigen-antibody interactions
    interacts till the antigen is altered resulting in death of microbes with the antigen.
  65. agglutinins
    other antibodies react with antigens on surface of bacteria. action causes clumping (agglutination) of microbes and enchances phagocytosis
  66. precipitins
    antibodies that react with dissolved antigens and conert them to soild precipitates, this form of antiges are usually inactive and more easily phagocytized
  67. antigen-antibody interaction involving complement system
    • by Jules Bordet
    • -complement system is a series of over 20 proteins that function in cascading set of reactions. set into motion by interaction of antigen and antibody molecules
    • -takes place on surface of cell
    • -increases permeability of cell membrane and induces cell to undergo lysis thru leakage of lfiud from cytoplasm
  68. type types of immunity.
    • -innate immunity
    • -acquired immunity
  69. innate immunity
    inborn capacity for resisting disease
  70. acquired immunity
    • depends on acitivity of T cells, antibodies, and other factors originating in immune system.
    • -an active and a passive immunity
  71. active immunity
    • if it develops when immune system responds to antigens and forms antibodies
    • -takes several hours or day to develop, but remains for long period of time
  72. passive immunity
    • if it develops when antibodies enter body from otuside source
    • -comes immediately when antibodies enter body, last only weeks
  73. active and passive further subdivided to 4 types.
    • 1. naturally acquired active immunity
    • 2. artificially acquired active immunity
    • 3. naturally acquired passive immunity
    • 4. artificially acquired passive immunity
  74. naturally acquired active immunity
    • follows a bout of illness
    • Memory T or B cells reside in lymphoid tisses remain active for year and produce IgG immediately if pathogen enters
  75. artificially acquired active immunity
    • develops after exposure to antigens in vaccine
    • -antigens may be toxoids, inactivated ciruses, synthetic viral parts, bacteria parts or other compents
    • -vaccines promote long-term immune response in form of memory T or B cells and IgG antibodies
  76. naturally acquired passive immunity
    • aka congential immunity
    • -develops when IgG antibodies pass from mother's bloodstream to fetal circulation via placenta and umbilical cord
    • -stays with child 3-6 months and fades as child's own immune system kicks in.
  77. artificially acquired passive immunity
    • arises from injection of antibody-rich serum into circulation
    • -form of therapy is used for serious viral diseases and toxin-related disease such as botulism and tetanus
    • -serum injected aka gamma globulin
    • -injections sometimes seen as foreigners by body

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