Microbio exam 4

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Microbio exam 4
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2014-07-21 16:00:43
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microbio immunity
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Microbio immunity
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  1. What is difference between infection and disease?
    Infection is invasion/colonization of the body by pathogenic microorganisms

    Disease occurs when an infection results in any change from a state of health
  2. What is the study of the manner in which a disease develops?
    Pathogenesis

    etiolology = study of cause of disease
  3. What is the difference between symptoms and signs?
    • Symptoms are subjective e.g. pain, malaise
    • Signs are objective which can be measured/observed eg blood pressure, swelling, lesions
  4. What is the difference between communicable and contagious diseases?
    • Communicable is any disease that spreads from one host to another (directly or indirectly)
    • Contagious means it EASILY spreads
  5. What are the two components in spreading disease?
    • Source! AKA Reservoirs - can be....
    • humans, animals, or nonliving

    • Transmission! can be via...
    • -direct contact e.g. touching, kissing
    • -indirect contact (via fomite= a general term for nonliving object involved in spread of infection) e.g. tissues, towels, bedding
    • -droplet e.g. coughing, sneezing, talking
    • -vehicle e.g. water, food, air, bodily fluids
    • -vectors e.g. mosquitos, flies, ticks, fleas
  6. What does incidence mean in terms of disease occurrence?  What about prevalence?
    The number of people that develops the disease in a time period

    Prevalence= ALL the cases (both old n new)
  7. Define acute, chronic, and latent infections?
    • Acute- a disease of short duration, develops rapidly eg influenza
    • Chronic- long lasting disease, develops slowly (no convalescent period eg TB or hepatitis B
    • Latent- the causative agent remains inactive (or dormant) for long periods eg shingles
  8. What is herd immunity?
    the presence of immunity in most of a population
  9. What is the overall, big picture in steps and requirements of an infectious disease?
    • -there must be a reservoir as a source
    • -pathogen must be transmitted to host (can occur by direct, indirect or by vectors)
    • -invasion, pathogen enters & multiplies
    • -injury to host, pathogenesis
  10. What are the 5 stages of illness for a general course of infectious disease
    1. Incubation period- interval between initial infection & 1st appearance of signs/symptoms

    2. Prodromal period- short interval, early & mild symptoms of disease e.g. aches & malaise

    3. Period of Illness- most severe signs & symptoms (if disease not txed pt dies)

    4. Period of Decline- signs & symptoms subside (pt vulnerable to secondary infection)

    5. Period of Convalescence- recovery, return to prediseased state

    ****Note that human can spread infection (act as a reservoir) AT ANY STAGE, even convalescence****
  11. Label the 5 stages:
    • *NOTE- Infection can be spread at ANY stage!!
  12. What are portals of entry?
    entrances to the human body for a pathogen to enter

    eg. mucous membranes, skin, or parenteral route (spots where skin/membranes are injured, like punctures, bites, cuts etc)
  13. What are portals of exit?
    specific routes that microbes use to leave the body e.g. secretions, excretions, discharges or tissue

    In general these routes are related to part of the body infected & will use the same portal for entry & exit
  14. What is preferred route of infection?
    Certain bacteria must gain access in a particular route in order to cause disease

    e.g. Salmonella typhi causes typhoid fever IF the bacteria is swallowed, if rubbed on skin, no disease.  Note that some bacteria have multiple preferred routes
  15. What is Adherence? How is it accomplished?
    Adherence- means of attachment of the pathogen to a host's tissues 

    Pathogens have surface molecules called adhesins or ligands that bind specifically to complementary surface receptors on cells of host's tissue
  16. What are the various ways bacteria can evade a host's phagocytic system of cells?
    capsules- bacteria that are encapsulated are more difficult for the body to destroy

    M protein- can reside in cell wall, it is a heat-resistant & acid-resistant protein.  It mediates attachment & resists phagocytosis by WBCs

    Also production of extracellular enzymes or antigenic variation (ability of pathogens to alter their surface antigens therefore evading host antibodies)
  17. If a pathogen overcomes a host's defenses, what are the 4 ways it can damage the host's cells?
    • 1. using host's nutrients
    • e.g. siderophores- proteins secreted by the bacteria that steal iron away from the host in various ways
    • 2. cause direct damage in immediate vicinity 
    • 3. produce toxins (which get transported all over the body via blood or lymph)  *Most common way*
    • 4. inducing hypersensitivity reactions
  18. What are toxins?  What are the two general types?
    toxin- poisonous substances produced by certain bacteria

    exotoxins & endotoxins
  19. What is the main difference between exotoxins and endotoxins?
    • exotoxin- produced INSIDE the bacteria then secreted or released following lysis. A PROTEIN
    • *they have an enzymatic nature, so small amount is dangerous b/c it can be used over and over again. mostly found in Gram + but also Gram - too

    endotoxin- Gram - only!  present in the outer part of cell wall, the LPS layer, specifically lipid portion (called lipid A).  They get released when bacteria dies.  A LIPOPOLYSACCHARIDE
  20. what are the various names of different exotoxins?
    • neurotoxins- attack nerve cells
    • enterotoxins- attack GI tract
    • cytotoxins- attack a wide variety of cells
  21. What are the 3 types of exotoxins?
    1. A-B toxins-- two parts, one binds and helps "break in", the other acts similar to an enzyme and disrupts protein synthesis

    2. Membrane-disrupting toxins-- cause lysis of host cells by disrupting their plasma membranes

    3. Superantigens-- antigens that provoke very intense immune response
  22. All endotoxins produce the same signs and symptoms, (to varying degrees), which are?
    • fever, chills, weakness, general aches, and sometimes shock and/or death.  can also induce miscarriage
    • also activation of blood-clotting proteins
  23. shock refers to any life threatening decrease in what?  Septic shock is caused by?

    And what can Gram - bacteria cause?
    • Shock = decrease in blood pressure
    • septic shock= shock caused by bacteria

    Gram - can cause endotoxic shock
  24. List 4 steps to pyrogenic response (fever) caused by endotoxins (aka Gram -)
    1. Gram - bacteria ingested by phagocytes

    2. As bacteria degrade, LPS layer is released (endotoxins too).  Endotoxins cause macrophages to produce cytokines-Interleukin 1 

    3. Cytokines are carried to hypothalamus

    4. Once at hypothalamus, lipids called prostaglandins are released, which reset the thermostat at a higher temp. Result is fever
  25. What is Immunity?  What are the two types?
    immunity- resistance to infection

    innate- defenses that are present from birth, responds rapidly

    adaptive- once innate lines of defense are breached, this 3rd level adjusts to handle microbe.  It's slower to response but has a memory
  26. What are Toll-like receptors (TLRs)?
    Protein receptors that hang in the plasma membrane of defensive cells (such as macrophages).  They activate the innate system.

    Basically they are detectors on the surface of macrophages & dendritic cells, they detect incoming Gram - bacteria by LPS or endotoxin
  27. What are Cytokines?
    proteins that regulate intensity & duration of immune responses.

    basically they are chemicals that get released by WBCs & trigger different responses in diff. types of WBCs
  28. Innate Immunity has two lines of defense. What makes up the first line?
    • Physical factors:
    • -intact skin, mucous membranes, (e.g. GI, respiratory & genitourinary system), and lacrimal apparatus 

    • Chemical factors:
    • -Sebum (oily substance produced by skin), and lysozyme capable of breaking down cell wall. Lysozyme is found in  mucous, perspirationtears and urine.
  29. What is the Lacrimal Apparatus?
    system of tear ducts that protect the eye, washes over the eye and lysosyme in the tears destroys pathogens
  30. What is a physical component of Innate Immune system's 1st line of defense that's found in the respiratory tract?
    Ciliary escalator- wave like cells in lung that push out particles & pathogens trapped in mucous
  31. What makes up the second line of defense in the innate immunity system?
    -phagocytes (e.g. neutrophils, eosinophils, dendritic cells, & macrophages)

    • -inflammation
    • -fever
    • -antimicrobial substances
  32. What is another name for WBCs?
    Leukocytes
  33. What is it called when you have a HIGH white cell count?
    Leukocytosis
  34. What is it called when you have a LOW white cell count?
    Leukopenia
  35. What are the two types of Leukocytes?
    • Granulocytes- WBCs that stain grainy under light microscope
    • e.g. Neutrophils, Basophils, & Eosinophils

    • Agranulocytes - don't stain grainy under microscope
    • e.g. Monocytes, Lymphocytes, Dendritic cells
  36. What are Neutrophils commonly called?
    • polymorphonuclear leukocytes (PMNs)  
    • aka polymorphs

    highly phagocytic & motile, active in initial response of infection
  37. what is major role of the following cells?
    Neutrophil
    Basophil
    Eosinophils
    Monocytes
    Dendritic cells
    Lymphocytes
    • Neutrophil- most active/motile
    • Basophil- releases histamine

    • Eosinophils- smaller, makes toxic proteins which damage parasites
    • Monocytes- are NOT phagocytic until they leave the blood & turn into MACROPHAGES

    • Dendritic cells- derived from monocytes, initiation of adaptive immune
    • Lymphocytes- Natural Killer (NK) cells, T cells and B cells; destroy target cells by cytolysis (cell bursts from too much ECF) and apoptosis (self destruction)
  38. What is a macrophage
    a phagocytic cell, a mature monocyte
  39. what is opsonization?
    enhancement of phagocytosis by coating microorganisms with certain serum proteins (opsonins); also called immune adherence
  40. What is inflammation? and what are the 5 signs?
    2nd line of defense, natural triggered response to damage done to body

    • 1. Redness
    • 2. Pain
    • 3. Heat
    • 4. Swelling
    • 5. Loss of Function
  41. What are the major processes of inflammation?
    • 1. damage
    • 2. vasodilation & increased permeability of blood vessels
    • 3. phagocyte migration & phagocytosis by macrophages & neutrophils
    • 4. repair
  42. What are acute-phase proteins?
    proteins that are released from damaged tissue.  induce both local & systemic responses (for example cause fibrinogen for blood clotting and kinins for vasodilation)
  43. What is vasodilation?  What is an important result of it?
    dilation of blood vessels  (it increases blood flood to area and is responsible for redness & heat associated with inflammation)

    It increases permeability this allows defensive substances normally held in blood to pass thru the vessels and enter injured area  AKA Vasopermeability
  44. What is margination?  

    And what is the process called that allows WBCs to pass through blood vessels?
    the process by which phagocytes stick to the lining of blood vessels (endothelium)

    Diapedesis- WBCs gather up and squeeze through to reach injured site
  45. What is the complement system?
    system of proteins that assist in destroying microbes.  Not adaptable, but sometimes is recruited and brought into action by adaptive immune system
  46. How does the complement system destroy microbes?
    1. cytolysis (pokes holes in membrane, ECF flows in and cell bursts)

    2. inflammation (vasodilation, margination of phagocytes, diapedesis)

    3. phagocytosis (via opsonization)

    *note complement proteins also prevent excessive damage to tissues
  47. How many complement proteins are there? How are they named?
    9

    designated with upper case C (C1-C9)
  48. How do complement proteins generally work?
    they are inactive until split into fragments (products).  They act in a cascade.  various C proteins will cause opsonization, cytolysis, & inflammation

    This cascade is called complement activation & may occur three ways
  49. What is the classical pathway?  What are the steps?
    1 of the 3 ways complement activation occurs.

    1. antibodies attach to antigens, forming complexes.  This complex bind & activate C1

    2. C1 in turn activates C2 & C4 (by splitting them).  They get split into C2a / C2b; C4a / C4b

    3. C2a and C4b combine and activate C3 by splitting it into C3a / C3b.  This fragments then initiate cytolysis, inflammation, and opsonization
  50. What are the 3 types of lymphocytes?
    • B cells
    • T cells
    • NK [natural killer] cells
  51. What is humoral immunity?
    immunity produced by antibodies dissolved in body fluids, mediated by B cells

    B lymphocytes making antibody
  52. What is cell mediated immunity?
    immunity from T lymphocytes
  53. What type of adaptive immunity do T lymphocytes make up?
    Cell mediated
  54. What type of adaptive immunity do B lymphocytes make up?
    Humoral
  55. What is an antigen?
    anything that provokes the immune response, usually a protein or polysaccharides

    Name is short for "antibody generators"
  56. What is an antibody?
    An antibody (Ab), also known as an immunoglobulin (Ig), is a large Y-shape protein produced by plasma cells.  

    It is used to identify and neutralize foreign objects such as bacteria and viruses.
  57. What are the 5 classes of Ig?
    • IgG
    • IgM
    • IgA
    • IgD
    • IgE
  58. Which class of Ig is the most prominent antibody?  (it's a monomer and majority of our protection comes from it).  it's long-lived.

    Accounts for how much % of all antibodies in serum
    IgG

    80%
  59. Which class of Ig is the FIRST to be produced in response to initial infection?  (it's a pentamer)

    Accounts for how much % of all antibodies in serum?
    IgM  (from macro, to reflect large size)

    • 5-10%
    • due to large size they generally stay in the blood cells, they are short lived
  60. Which class of Ig is generally found in secretions, mucous, mother's milk, or colostrums?  It is a dimer

    Accounts for how much % of all antibodies in serum?
    IgA

    10-15%

    IgG is most abundant in serum, while IgA is most abundant in the whole body
  61. Which class of Ig is associated with allergy or asthmatic response?

    Accounts for how much % of all antibodies in serum?
    IgE

    .002%
  62. What are plasma cells?
    a cell that an activated  B cell differentates into; plasma cells manufacture specific antibodies
  63. What are memory cells?
    a small set of B cells that stays with us for life & will secrete the antibody we have previously made against a known pathogen
  64. What are T helper cells?
    CD4+

    works with macrophage & B cells to help produce antibody

    APC encounters antigen, it gets broken down inside APC (eg dendritic cell) and these fragments combine with MHC complex which puts a signal at cell's surface.  This signal "calls" and binds to T helper cell which releases cytokines to stimulate immune systems
  65. What are antigen-presenting cells?
    they process antigens so that T cells may recognize them.  T cells then become activated and release Interleukin 1 and B cells become primed to make antibody
  66. What are T killer cells?
    • CD8+
    • subset of T cells that kill already infected cells
  67. Adaptive Immunity has two methods of function, Naturally acquired & Artificially acquired.

    What are examples of the passive and active forms for the Naturally acquired routes?
    Active in NATURALLY ACQUIRED: antigens enter body naturally, body responds

    Passive in NATURALLY ACQUIRED: antibodies pass from mom to baby (via placenta or moms milk)
  68. Adaptive Immunity has two methods of function, Naturally acquired & Artificially acquired.

    What are examples of passive and active forms for the Artificially acquired routes?
    Active in ARTIFICIALLY ACQUIRED: antigens are introduced via vaccines, body responds

    Passive in ARTIFICIALLY ACQUIRED: premade antibodies in serum get injected
  69. What are attenuated vaccines?
    whole agent vaccines where pathogen has been weakened so it's not strong enuff to cause a rapid/quick infection.  This gives body time to respond and make antibodies.   We keep these antibodies as protection in case we encounter the pathogen in nature
  70. What are inactivated vaccines?
    similar to attenuated vaccines, except instead of a weakened pathogen, it's KILLED and only the shell remains to prime the immune system into response.
  71. what are conjugated vaccines?
    when a polysaccharide vaccine is joined to a protein to make it more potent.

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