Up to Midterm #1

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Up to Midterm #1
2011-01-26 14:31:39
Medical Microbiology

practise practise
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  1. 2 types of host-resistance that work together
    • non-specific host resistance
    • specific host resistance
  2. Antigen-presenting cell (APC):
    • cells that take on protein antigens, process them, and present antigen fragments to other cells, activating them.
    • Macrophages, B cells, and dendritic cells can act as APC’s.
  3. Describe the mechanism by which clonal selection provides immune memory via both B-cell and T-cell dependent mechanisms.
    • A anitgen will be specific to a B cell.
    • a certain antigen will activate a specific B cell
    • That activated B cell migrates, and proliferates to produce 2 kinds of cells: a plasma cell to act on the antigen, and a memory cell. The memory cell will recognize the antigen in the next encounter and react much quicker, much stronger.
    • T cells must be activated by specific MHC-antigen peptide combinations, once activated the T cells proliferate to form effector cells, as well as memory cells
  4. Describe how non-specific defense mechanisms work with specific defense mechanisms to fight infection.
    Cellular immunity is based on the action of T cells. T cells are an important component of the specific immune system. The systems work in collaboration with nonspecific immune systems when T cells release special chemicals known as cytokines. Cytokines enhance specific immunity and nonspecific immunity defenses such as phagocytosis and inflammation.
  5. Naturally aquired immunity
    • is when an organism aquires antigens from another organism through natural transfer
    • ex. a mothers blood transfers antigens across the placenta to her fetus
  6. Artificially Acquired immunity
    • when an organism acquires immunity (antigens) from a preperation to induce the formation of antibodies and activated lymphocytes
    • ex. Vaccination is a prepared vaccine administered to an organism
  7. Active immunity
    • immunity that has been prepared and is active
    • ex. a vaccine can can provide activated immunity because it is prepared with a killed or attenuated organism to induces the organism to produce antibodies for the anitgen - gives memory for the real attack
  8. Passive immunity
    • immunity that has been acquired to the transfer of antigens that have been produced by another organism
    • ex. a human suffering botulism food poisoning is administered botulinum antitoxin produced by a horse
  9. Responds to nonself with:
    Effector response - Eliminates or
    renders foreign material harmless

    Memory response - (2nd infection has more
    intense response)
    the specific immune system
  10. this immune system has Humoral immunity:
    antibody-mediated immunity (proteins secreted by B cells)
    innate immune system
  11. this immune system has Cellular immunity: based on action of specific kinds of T cells
    the specific immune system
  12. MHCII is found on all cells?
    Falses only presented on antigen-presenting cells.
  13. The following examples belong to which immune system?
    Skin, WBC, macrophages,
    stomach acid, chemicals in the bloodstream
    non-specific immune system
  14. define Bacteriocins
    are proteinaceous toxins which kill bacterial cells of the same or similar species that lack certain bacteriocin factors. Source of bacteriocin is genes carried on a transposon or plasmid. An example of how they work, they form channels in cell membrane that allow potassium ions and protons to leak out. Narrow spectrum of antimicrobial activity,
  15. define Cationic Peptides
    evolutionarily conserved component of the innate immune response and are found among all classes of life. Fundamental differences exist between prokaryotic and eukaryotic cells that may represent targets for antimicrobial peptides. have broad spectrum of antimicrobial activity including activity against bacteria, eukaryotic parasites, viruses, and fungi. Vary considerably in sequence and structure, with few common features. Are amphipathic meaning they possess both a hydrophobic region that interacts with lips and + charged hydrophillic region that interacts with water or - charged residues. affects both Gram +, Gram -, works well against antibacterial bacteria. negative charged regions can bind to membrane lipids and fold into membrane-bound structures leading to: cell lysis,channel formation, attacks internal targets, breakdown of membrane integrity