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Immunity

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Innate immunity - genetically determined. people not susceptible to same diseases as gold fish. Active ... Passive immunity - Ab from one individual to another ... – PowerPoint PPT presentation

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Title: Immunity


1
Immunity
2
Nonspecific Defense
  • Skin and Mucous Membranes
  • acid sweat pH 3?5
  • enzyme in perspiration, tears, sweat, and saliva
  • lysozymes - attacks bacterial cell walls
  • respiratory tract contains cilia and mucus
  • digestion - acid in the stomach

3
Leukocytes
  • neutrophils - chemotaxis - attracted by chemical
    signals
  • self-destruct when destroying others
  • few day life span
  • monocytes - morph into macrophages longer lived
  • amoeboid cells - ingest bacteria, viruses, and
    cell debris
  • some bacteria have defenses to these
  • eosinophils - cytoplasmic granules with enzymes
    used against invaders discharged
  • mainly attack parasites (worms)
  • natural killer cells - kill off infected cells of
    own body - very versatile in what attack
  • recognize new/unusual proteins on the plasma
    membrane
  • more rapid response than other cells
  • may stop tumors and virus infestations
  • poke hole in plasma membrane - proteins called
    perforins
  • plasma cells - produce Ab that are in blood

4
Antimicrobial Proteins
  • complement - proteins that ID and dagger invaders
  • interact with other defense mechanisms

5
Antimicrobial Proteins
  • interferon - virus infested cell (and activated
    lymphocytes and macrophages)
  • releases substances that will improves nearby
    cell defenses
  • increase protein production that inhibit viral
    replication
  • especially for short term infection - cold and
    flu
  • activates phagocytes

6
Interferons
7
Inflammatory Response - pain, heat and swelling
  • damaged cells release prostaglandins, proteins,
    and K
  • vasodilation increase blood supply
  • histamines released (from mast cells or
    basophils) cause localized vasodilation
  • prostaglandins also help this to happen
  • heparin reduces clotting so new cells keep coming
    and cleansing
  • later a clot forms to seal off and slow spread of
    pathogens
  • increased temperature (increased blood flow) -
    activates/catalyzes enzymatic reactions of
    phagocytes
  • may also denature foreign enzymes or proteins
  • phagocytic cells migrate to area - via complement
    proteins and other factors
  • 1st neutrophils activation - increased
    metabolic activity
  • release H2O2 and nitric oxide to kill of
    pathogens
  • invade then die
  • macrophages remain to protect
  • may get pus from dead cells and fluid during
    clean up
  • severe infection ? systemic response
  • bone marrow releases more neutrophils
  • increase leukocytes
  • fever - due to pathogens or proteins called
    pyrogens that re-set temp for battle

8
Lymphatic System - tissues and free cells
  • Cells T cells (thymus-dependent) cells, B cells
    (bone marrow derived) and Natural Killer cells
  • lymph node lymph tissue wrapped in fibrous CT
  • percolate out unwanted - capture cancer cells

9
Temperature
  • fever - stimulates phagocytosis
  • inhibits microbial growth
  • reduces Fe that bacteria need
  • speeds up tissue repair

10
Specific Response
  • T Cells start in bone marrow ? thymus where
    mature
  • Cell mediated response
  • ID via antigens produced
  • Several kinds of effector cells
  • Helper - initiate humoral and cell mediated
    response
  • stimulate activation of both T cells and B cells
  • Cytotoxic - lyse cell infected w/ virus or cancer
  • production of cell mediated immunity
  • some serve as memory
  • no response on first exposure, but many made
    for next time
  • Natural Killer cells lymphocytes
  • surveillance of cells
  • attack foreign cells, viral infected cells and
    cancer cells
  • Inducer development of T cells in thymus
  • B Cells - bone marrow
  • Humoral response or Ab response
  • ID antigen and the start to reproduce --gt plasma
    cells ( effector cells)
  • which secrete Abs that flag antigens for
    destruction

11
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12
Strategies
  • Innate immunity - genetically determined
  • people not susceptible to same diseases as gold
    fish
  • Active immunity - after exposure to an antigen
  • own immune system - has many capabilities these
    are stimulated after exposure
  • Natural from infection - starts to develop after
    birth
  • develops on an as needed basis
  • Artificial (Induced) - deliberate exposure
  • from vaccination/immunization
  • and the forced version where your Mom forced
    you to play with the kid with chicken pox so you
    could develop immunity
  • Passive immunity - Ab from one individual to
    another
  • usually short lived
  • example mother to fetus - across placenta, in
    milk
  • can also be artificial (induced)

13
Humoral response
  • Ab immune response to toxins, bacteria, and
    viruses
  • Ab production from lymphocytes, carried on B
    cells plasma membrane
  • if antigens bind to Ab then the B cells are
    sensitized
  • sensitized B cell encounter an already activated
    helper T cell
  • B cells then usually --gt mitosis --gt plasma cells
    and memory B cells
  • Memory B cells --gt 2nd exposure --gt mitosis

14
Ab aid to destroy antigens
  • Neutralize - land on specific site on pathogens
    needs to enter host cells

15
Ab aid to destroy antigens
  • Agglutination and precipitation - form bridges
    between two pathogen cells
  • Ab can bind on two spots - tips of Y

16
Ab aid to destroy antigens
  • Activate complement - when bound to antigen
  • change in shape so compliment proteins bind
  • complements proteins that supplement the
    action of Abs
  • destroy target cells plasma membrane - create a
    pore

17
Ab aid to destroy antigens
  • stimulate inflammation - basophils and mast cells
  • attract phagocytes - neutrophils and macrophages
  • makes target easier for macrophages to engulf
  • gives phagocytes something to hang onto
  • vs slick cell membrane of some bacteria
  • Attract phagocytes - eosinophils, neutrophils,
    macrophages
  • Prevents bacteria and viral adhesion
  • makes it hard for pathogens to attach

18
Cell mediated response
  • attack viruses, abnormal cells, bacteria, fungi,
    protozoans, worms,
  • transplant tissues, cancer cells
  • T cell activation - before immune response must
    activate by exposure to antigen
  • Major histocompatibility complex (MHC)
    glycoprotein self markers
  • unique to each individual
  • MHC Class I membranes of all nucleated cells,
    from golgi
  • if abnormal peptides are present ? T cell
    activated
  • common for viruses to bind here
  • MHC Class II found only in Antigen presenting
    cells
  • all monocytes/phagocytes microglia, in CT,
    in liver
  • T cells are specific to an antigen - only
    activated to certain antigens
  • Memory - based upon memory cells from 1st
    infection
  • 1st immune response increase lymphocytes to
    form clones of effector cells
  • 2nd immune response faster, Ab more effective
    at binding to antigen
  • from second time infected
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