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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
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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
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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
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social implications
- grief family/friends
- families = poor due loss wage, refusal life insurance
- stigmatizing, no partners, friends, housing, employment
- decrease sex act for fear
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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
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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
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outline life of b cell
- mature in bone marrow, shafts large bone
- move from there to lymphatic organs
- differentiate into 2 cells -> memory, plasma
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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
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memory cells (b cells)
- long lived memory cells
- remember antigens -> encounter = rapidly differentiate into antibody producing plasma cells
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plasma cells (b cells)
- when stimulated by antigen some b cells -> plasma cells
- secrete antibodies into blood system
- antibodies inactivate circulating antigens
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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
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function t cell
- responds only to antigen fragments tt have been processed presented by infected cells/macrophages
- defend against intracellular antigens
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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
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5 steps detail antibody production
- process takes few days
- antigen presentation
- activation helper t cells
- activation b cells
- production plasma cells
- production memory cells
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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
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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
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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)
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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
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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
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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
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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
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polyclonal selection
- sometimes sev diff types antibody bind to same antigen more than one clone cell produced
- occurs w/ some infec diseases
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