immune system 2

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immune system 2
2013-01-17 10:19:25
immune bio

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  1. AIDS
    • acquired immunodeficiency syndrome
    • results variety symptoms prod. one virus (HIV)
    • symptoms: loss of helper T cells (lymphocytes) weight loss, autoimmune diseases, rare cancers + variety infections
  2. cause
    • retrovirus, RNA as genetic material instead DNA
    • uses lymphocytes (helper T cells) as host -> destroys + prevent produc. antibodies
    • decline o immune syst leaves body vuln. to pathogens
    • person dies fr diseases fr weakened immune syst
    • disables immune syst so no primary/secondary resp
  3. transmission
    • can't survive long outside body, cant pen. broken skin
    • trans fr body fluids fr infected to uninfected
    • small cuts, tears, during parts during sex
    • traces blood on hypod. needle shared by drug users
    • across placenta, cuts, through milk
    • transfused blood/blood products hemophiliacs
  4. social implications
    • grief family/friends
    • families = poor due loss wage, refusal life insurance
    • stigmatizing, no partners, friends, housing, employment
    • decrease sex act for fear
  5. effects HIV on immune system
    • reduction number active lymphocytes (helper T cells)
    • loss o ability to produce antibodies
    • (d) The infected lymphocyte is 'disabled' by the virus
    • (e) When an antigen infection is presented the lymphocyte cannot produce antibodies.
    • (f) The antigen is not challenged by the immune system and is able to freely proliferate

  6. stages of infection HIV
    • loss o ability to produce antibodies + reduction in number active lymphocytes
    • initial infection HIV positive w/ little no symp
    • viral load increases sharply, helper T cell populations costs load to diminish
    • some host cells infected
    • viral load increases
    • helpter T cells decrease
    • immune response suppressed
  7. outline life of b cell
    • mature in bone marrow, shafts large bone
    • move from there to lymphatic organs
    • differentiate into 2 cells -> memory, plasma
  8. role o b cells
    • recognize and bind free antigens
    • each b cell recog one specific antigen
    • helper T cells recog speci antigens on B cell surfaces + induce maturation and proliferation
    • b cells defend against bacteria/viruses outside cell
  9. memory cells (b cells)
    • long lived memory cells
    • remember antigens -> encounter = rapidly differentiate into antibody producing plasma cells
  10. plasma cells (b cells)
    • when stimulated by antigen some b cells -> plasma cells
    • secrete antibodies into blood system
    • antibodies inactivate circulating antigens
  11. life of t cell
    • from thymus gland, contains immature t cells
    • 4 kinds: helper t, suppressor t cell, cytotoxic t cell,t cell for delayed hypersensitivity
  12. function t cell
    • responds only to antigen fragments tt have been processed presented by infected cells/macrophages
    • defend against intracellular antigens
  13. role o diff t cells
    • helper t cell: activates cytotoxic t cells other helper t, necessary for b cell activation
    • suppressor t cell: regulates immune response, turns off when no more antigen present
    • cytotoxic t cell: destroys target cells on contact, recog virus infected cells by surface
  14. 5 steps detail antibody production
    • process takes few days
    • antigen presentation
    • activation helper t cells
    • activation b cells
    • production plasma cells
    • production memory cells
  15. antigen presentation
    • macrophages take in antigens receptor mediated endocytosis
    • processes them + attach them to membrane proteins = MHC proteins
    • MHC carry antigens display on surface antigen presentation
    • migrates to the lymph node
  16. activation helper t cell
    • inactive helper t cell have receptors in plasma memb tt binds to antigens pres by macrophages
    • each helper t cell has same antigen binding domain as antibody
    • receptors allows t cell recog antigen and bind, passes signal to helper t cell activates it
  17. activation b cells
    • inactive b cells have antibodies in pm
    • if antibodies match antigen, antigen binds to antibody
    • activated helper t cells w recep for same antigen bind to b cell sends signal -> activates
    • stimulates B and T lymphocytes divide rapidly (important in coordination)
  18. production plasma cells
    • activated b cells divide mitosis form clone o cells = active with greater cytoplasm
    • lots of ReR for protein synthesis
    • make large amounts antibodies secreted by exocytosis
  19. production memory cells
    • memory cells formed same time as activated helper t cells and b cells
    • allow rapid response if disease encountered again -> long term immunity
  20. b cells and antibody production
    • many diff types lymphocytes exist, each recog specific antigen, makes spec. antibodies
    • large number diff lymphoc exists 1015
    • each puts some antibodies it can make onto cell surface (antigenic receptors)
    • millions diff types b cells
    • each capable o production antibodies (immunoglobins) to diff antigens even never encountered
    • each b cell ONE specific antigenic receptor in pm identical to antibody it can prod
    • antigen presentation by macrophages + activation helper t cells -> activate b cells, divide clones o antibody secreting plasma cells and memory cells
    • multiples form clone plasma cells tt will secrete specific antibody
  21. clonal selection + principle challenge and response as basis o immunity
    • principal challenge + response: immunity only develops if immune system challenged by disease -> response
    • clonal selection is antigen driven cloning b cells, antigen selects b cells tt will proliferate
    • clone b cells plasma cells can prod lrg amnts antibodies
    • some differentiate into memory cells
    • antigen molecules bind to antigen receptors
    • -> mitosis b cell proliferates -> become long lived memory cell or short lived plasma cells tt secrete antibodies
    • results in immunity
    • see polyclonal selection too
  22. polyclonal selection
    • sometimes sev diff types antibody bind to same antigen more than one clone cell produced
    • occurs w/ some infec diseases