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2012-05-07 17:15:09
immune system

immune system
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  1. describe the first line of defense against harmful agents including examples of each type:
    • Non- specific: doesnt depend on prior exposure
    • external barriers: skin and mucous membranes
  2. viruses, bacteria, fungi and other microbes that cause disease are called:
  3. describe the mechanisms of action in skin of the first line of defense against harmful agents:
    • skin
    • keratin: a tough protein that few pathogens can penetrate, provides phyiscal barrier
    • defensins: peptides that destroy (kill) bacteria, viruses, and fungi
    • sweat: provides a thin flim of lactic acid that inhibits bacterial growth
  4. describe the mechanisms of action in the mucous membranes of the first line of defense:
    • traps foreign particles
    • lysozyme: an enzyme that destroys bacteria by dissolving their cell walls
  5. describe the second line of defense against harmful agaents including exmples of each type:
    • non- specific
    • internal barriers: leukocyte/macrophages, antimircobial proteins, immune surveillance, inflammation and fever
  6. describe the leukocytes and macrophages mechanism of action in the second line of defense againse harmful agents:
    • esoinophils: kill parasites
    • basophils: produces histamin and heparin
    • neutrophils: kill bacteria
    • monocytes: become macrophages
    • B- lymphocytes: humeral immunity
    • T- lymphocytes: secrete cytokines ( interleukins - WBC communications)
    • NK cell: immune surveillance
  7. describe the antimicrobial protein,interferon, mehcanism of action in the second line of defense against harmful agents:
    • when certain cells (espcially leukoctyes) are infected with viruses, they secrete proteins called interferon
    • break down viral genes, and prevent viral replication
    • activate NK cells/macrophages: destroy infected cells

    infected cells secretes interferon> interferon receptor> antiviral protein > no replication
  8. describe the antimicrobial protein complement system's mechanism of action in the second line of defense againse harmful agaents:
    30 proteins activated by presences of pathogens

    • 4 pathways of mechanism
    • 1. inflammation: attracts neutrophils and marcophages
    • 2. immune clearance: pathogens cleared in the liver and spleen
    • 3. phagocytosis: opsonization- increases # and types of binding sites
    • 4. cytolysis: drills holes in pathogen cell membrane
  9. descrribe the anitmicrobial protein, immun surveillance, mechanism of action in the second line of defense against harmful agents:
    • 1. Nk cells release perforins which polymerize and form a hole in the enemy cell
    • 2. granzymes from NK cell enter perforin's hole and degrade enemy cell enzymes
    • 3. enemy cell dies by apoptosis (programmed cell death)
    • 4. macrophages engulf and digest dying cell

    *Nk Cells target: bacteria, transplanted cells, viral infected cells, and cancer cells
  10. describe the antimicrobial protein, fever, mechanism of action in the second line of defense of defense against harmful agents:
    • abnormal elevation in body temperature
    • promotes interferon activity
    • accelerates tissue repair
    • inhibits bacterial reproduction

    • 1. infection and pyrogen (fever producting agents) secretion
    • 2. hypothalamic thermostat is reset to higher set point
    • 3. onset - body temperature rises
    • 4. stadium - body temp. oscillates around new set point
    • 5. infection ends, set point returns to normal
    • 6. defervescence (body temp. returns to normal)
  11. describe the antimicrobial protein, inflammation, mechanism of action in the second line of defense against harmful agents:
    • signs: redness and swelling
    • symptoms: heat and pain
    • cytokins - cause vasodilation > increase leukocytes to site, destroy pathogen, clean up debris, > increase fibrogen - prevents spread of pathogen, set matrix for tissur repair> increase nutrient and growth factors for tissure repair
  12. describe the characteristics of the third line of defense against harmful agents:
    • sepcificity: antigens, molecules that trigger an immune response to a given antigen and no other
    • memory: ability of the body to fight subsequent antigen on 2nd or more exposure
  13. describe the cells involved and the mechanisms of action in the thrid line of defense against harmful agents:
    • B lymphocytes: mature (become immunocompetent) in the bone marrow, abundant in the lymph nodes, spleen, bone marrow, and mucous membranes, humeral immunity
    • T lymphocytes: mature (become immunocompetent in the thymus, tested to recongize "self from non-self" (only 2% pass), cellular immunity
    • antigent-presenting cells (APC): include macrophages and B lymphoctyes, express MCH (major hisotcompatibility complex, histology) proteins, present and process on MHC proteins - looking out for the body against "foreigners", assist T cells to ID foreign antigens
    • 1. phagocytosis of antigen
    • 2. lysosome fuses with phagosome
    • 3. antigen and enzyme mix in phagolyososome
    • 4. antigen is degraded
    • 5. antigen residue is voided by exocytosis
    • 6. processed antigen fragments (epitopes) displayed on macrophage surface
    • *this is an intracellular process*

    each person has their own specific MHC's, T Cells inspect APCs- if "self" do nothing, if " non-self" initate, immune response, process are biochem based
  14. describe the different types of thrid line of defense against harmful agents:
    • cell mediated: T cells directly attack foreign/diseased cells
    • humoral immunity: antibodies tage pathogens for destruction, work only extracellularally

    • body makes
    • natural active-immunity: immunity frfom natural exposure ("get sick")
    • artifical active: vaccination (hepatitis, tetanis)

    • body acquires
    • natural passive: fetus from placenta; baby from breast milk
    • artifical passive: injection of immune serum (rabies, hepatitis, tetanus)
    • * no memory of acquired

    • active is long term (years)
    • passive is short term (2-4 weeks)
  15. describe the types of cells involved in cellular immunity:
    • cytotoxic T (Tc) cells: attack/fight against enemy cells (aka killer T cells), directly destroys nucleated foreign cells (these are not natural killer cells)
    • helper T (TH) cells: coordinates immune response, "in charge" cells, attracts TC cells, neurotphils, macrophages, secretes interleukins, roles in nonspecific immunity/humoral response
    • suppressor regulatory T (TR) cells: suppressses T/B cell activity, if not suppressed then autoimmune disease can occur
    • memory T (TM) cells: memory after being infected, ex: vaccines
  16. describe the mechanism of T Cell activation i cellular immunity:
    • 1. antigen recognition
    • 2. Costimulation: the T cell has to check twice to see if it really has bound to and APC displaying a foreign antigen
    • 3. clonal selection: repeated mitosis, giving rise to a clone of identical T cells programmed against the same epitope
    • 4. Lethal hit - destruction of enemy cell and interleukin secretion - activity of NK, B or Tc development of memory T cells, inflammation and other non specific defense
  17. describe the immune system disorder of allergies:
    • at reaction to environmental antigens
    • an allergen binds to the IgE on the membrane of basophils and mast cells
    • stimulates basophil to release histamine and other inflammatory and vasoactive chemicals
  18. describe the immune system disorder of asthma:
    inflammatory rxn to inhaled oxygen
  19. describe the immune system disorder of anaphylaxis:
    an allergen is introduced into the bloodstream, characterized by bronchoconstriction, vasodilitation, and circulaory shock
  20. describe the immune disorder of HIV/AIDS:
    • virus attacks the Helper T cells
    • low # of helper T cells < 200/microliter (normally 600 -1200/microliter)
    • subccumb to opportunistic infections
  21. describe the autoimmune diseases:
    immune system fails to distinguish self antigens from foreign ones and produces autoantibodies that attacks the bodys own tissues
  22. list and describe the 4 autoimmue diseases of the immune system:
    • rheumatic fever: produces antibodies that attacks the heart valves
    • lupus: antibodies against DNA - connective tissue inflammation or renal failure
    • myasthenia gravis : antibodies attack ACh receptors at neuromuscular junction
    • Rhumatoid arthritis: antibodies against synovial membranes, articular cartilage degrades
    • graves disease:
  23. describe the role of the Helper T cells in non- specific defense:
    • Activated Helper T cell >
    • marcrophages + NK cells are then activated >
    • secrete>
    • cell killing chemicals and destroy target cell
  24. describe the role of Helper T cells in cellular immunity:
    • infected cell >
    • cytotoxic cell >
    • perforin (water moves in the cell swells, and die, virus can not replicate)

    * clonal selection of cytotoxic T cells
  25. describe what humoral immunity is:
    • indirect method of defense
    • B lymphocytes produce antibodies that bind to antigens and tag them for destruction by other means
  26. describe the recognitition stage of humoral immunity:
    • immunocompetent B cells exposed to antigen. antigen binds only to B cells with complementary receptors
    • antigen presentation: B cell internalizaes antigen and displays processed epitope. Helper T cells binds to B cells and secretes interleukin
  27. describe the role of plasma cells in the recognition stage of humoral immunity:
    • contain an abundance of rough endoplasmic rectiulum
    • produce antibodies until they die
    • secrete antibodies at a rate of 2,000 molecules/second for a life span of 4-5 days
    • develop in the lymph nodes
  28. describe the fxn of immunoglobulins:
    • neutralize toxins/virus
    • activates complement cascade
    • mark for immune clearance
  29. describe the fxn of IgA:
    • found in mucus, tears, milk, saliva, and intestinal secretions
    • provides passive immunity for newborns (breastmilk)
  30. describe the fxn of IgD:
    • Signals B cell activation
    • basophils attract esoinophils
  31. describe the fxn of IgE:
    stimulates basophils to release histamine for asthma and allergies
  32. describe the fxn of IgG
    • 80% of anitbodies in blood plasma
    • predominate antibody secreted in secondary immune response
    • crosses placenta - anti D antibody (Rh)
  33. describe the fxn of IgM:
    • 10% circulation in blood plasma
    • predominate antibody secreted in the primary immune response
    • anti A, anti B and ABO blood group
  34. One way the body defends against the spread of viral infection is that virus-infected cells secrete proteins called ____________, which protect neighboring
    cells by preventing viral replication in them.

    endogenous pyrogens
  35. Fever and inflammation are considered forms of _____________ and are part of the _____________.

    specific immunity; third line of defense
    specific immunity; second line of defense
    non-specific resistance; second line of defense
    non-specific resistance; first line of defense
    specific immunity; first line of defense
    non specific resistance; second line of defense
  36. Leukocytes communicate with each other by paracrine messengers called ____________.

    MHC proteins
  37. Humoral immunity is characterized by all of the following EXCEPT:

    A. Memory B cells respond rapidly when reexposed to a pathogen.
    B. Cytotoxic T cells directly destroy foreign cells.
    C. Helper T cells secrete interleukins.
    D. Plasma cells make antibodies.
    E. B cells serve as antigen-presenting cells (APCs).
    F. C and D
    B. cytotoxic T cells directly destroy foreign cells
    (this multiple choice question has been scrambled)
  38. HIV, the virus that causes AIDS, directly attacks which type of immune cell?

    B cells
    cytotoxic T cells
    plasma cells
    helper T cells
    helper T cells
  39. Which type of antibody provides passive immunity to newborn babies because it is found in secretions such as breastmilk?

  40. Receiving an injection of immune serum is a form of ___________ immunity.

    natural active
    natural passive
    artificial active
    artificial passive
    artificial passive
  41. Natural killer cells (NK cells) are activated as part of the cell-mediated (cellular) immune response.

  42. Which of the following cell types is essential for coordinating the immune response by playing key roles in non-specific resistance and cellular and humoral immunity?

    plasma cells
    cytotoxic T cells
    NK cells
    memory B cells
    helper T cells
    helper T cells
  43. Which of the following, when activated, leads to enhanced inflammation, immune clearance, phagocytosis, and cytolysis?

    NK cells
  44. Inflammation is characterized by vasodilation.

  45. B cells must migrate to the thymus to become immunocompetent.

  46. describe the 2 responses in the memory stage of humeral immunity:
    • primary response: when a person is exposed to a particular antigen for the first time, appearance of antibodies is delayed for 3 - 6 days to allow time for B cells to convert to plasma cells
    • secondary response: during colonal seclection some B cells become memory B cells rather than plasma cells, significant increase # of antibodies within hours of reexposure