Study Guide BIO205 Ch#16

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Study Guide BIO205 Ch#16
2013-04-30 19:56:37
Study Guide BIO205 16

Study Guide BIO205 Ch#16
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  1. Naturally acquired active immunity?
    • Body responds to pathogens, other antigens by mounting a specific immune response
    • Get sick with the disease
    • Body is naturally & actively responding
  2. Naturally acquired passive immunity?
    • Embryos and newborns acquire preformed antibodies from their mother
    • Across the placenta – IgG
    • In mother’s milk – IgA
    • Child not actively producing own antibodies
  3. Artificially acquired active immunity?
    • Vaccines – live attenuated or heat-killed Ag
    • Patient’s own body responds against antigen
    • Basis of immunization
  4. Artificially acquired passive immunity?
    • Antibodies harvested from animals/humans, given to protect patients immediately
    • Active immunity takes days to weeks to fully protect – delay may prove detrimental or fatal if protection not given immediately
    • Rabies, hepatitis A
    • May give antisera or antitoxins
  5. What are the 5 attributes of adaptive immunity?
    • Specificity
    • Inducibility
    • Clonality
    • Unresponsiveness to self
    • Memory
  6. Specificity?
    • Response to only 1 molecular shape
    • (antigen, target is specific)
  7. Inducibility?
    • Immune cells activated only in response
    • to specific pathogens
  8. Clonality?
    • Once induced, cells of adaptive immunity
    • proliferate to form clones
  9. Unresponsiveness to self?
    • No reaction against normal body
    • cells
  10. Memory?
    • Remembers specific pathogens and
    • responds faster and more effectively in subsequent encounter
  11. What are the general roles of B cells and T
    cells in adaptive immunity?
    • B lymphocytes (B cells) attack extracellular pathogens in humoral immune responses, using antibodies.
    • T lymphocytes (T cells) carry out cell mediated immunity against intracellular pathogens
  12. What are the primary lymphoid organs, and
    secondary lymphoid organs?
    • Primary:red bone marrow and thymus
    • Secondary:lymph nodes – filter lymph
    • spleen – filters blood
    • Less organized mucosa-associated lymphatic tissue (MALT): tonsils, appendix, Peyer’s patches, ymphoid tissue in respiratory tract, vagina, bladder, mammary glands
  13. Where do lymphocytes originate, and where do
    they mature?
    • all originate in red bone marrow
    • •B cells mature in bone marrow
    • •T cells mature in thymus
    • •B and T cells migrate to 2o lymphoid organs
  14. Where are lymph nodes found, and what is their function?
    • in neck, groin, armpit, abdomen
    • Lymph nodes facilitate interactions between immune cells and pathogens
  15. Describe the flow of lymphatic fluid.
    • Leaks out of blood stream into tissues
    • Collected from tissues by lymphatic vessels and carried to lymph nodes
    • Lymph nodes filter the lymph
    • Empties back into blood stream
  16. What are antigens?
    Substances that trigger specific immune responses.
  17. What are epitopes?
    (or antigenic determinant) is the three-dimensional shape of a region of an antigen that is recognized by the immune system
  18. Exogenous antigens?
    On microorganisms that multiply outside cells of body
  19. Autoantigens?
    • Body should not attack antigens on surface of its own normal cells
    • This is “self tolerance”
  20. Endogenous Antigens?
    Protozoa, fungi, bacteria, and viruses that reproduce inside body’s cells
  21. Describe properties and types of antigens?
    • Larger molecules better antigens than smaller ones
    • Have more epitopes
    • Proteins and glycoproteins are good antigens
    • Carbohydrates and lipids less antigenic
    • Small molecules, called haptens, (like penicillin) make poor antigens
    • If bind to a large carrier molecule, can become antigenic
  22. Describe B cells?
    • B cells make immunoglobulins (Ig),= antibodies
    • B cells have receptors for antigens
    • Surface of B cell covered with many identical copies of B cell receptor
    • Variable regions of heavy and light chains form antigen-binding site
  23. what happens when B cells are activated?
    When activated by a specific antigen (usually occurs in lymph node), B cell reproduces and make lots of clones; some become plasma cells, and some become memory cells for quick responses later when same antigen is encountered again
  24. Describe Antibodies?
    • Complement Activation- FC region binds to complement protein
    • Neutralization - blocks action of toxin or attachment of pathogen
    • Opsonization - makes phagocytosis easier
    • Direct killing by oxidation
    • Agglutination
    • Antibody-dependent cellular cytotoxicity  Antibodies bind to pathogen’s epitopes
    • Fc region binds to natural killer cells, which lyse pathogen (apoptosis) with proteins called perforin and granzyme
  25. Antibodies?
    Antibodies are complementary to epitopes and consist of 2 light chains and 2 heavy chains, y-shaped molecules
  26. What are the five classes of antibodies?
    • nIgM
    • IgG
    • IgA
    • IgE
    • IgD
  27. Antibodies
    • Plasma cells first make 
    • 5 basic units linked together in a circle by a joining chain
  28. Antibodies
    • IgG is usually made next
    • Most common, longest-lasting Ab
    • Single unit
    • Plays many roles in the body
    • Can easily leave blood vessels to enter extracellular spaces, where invaders often are located
    • The only antibody to cross placenta
  29. Antibodies
    • Associated w/ secretions– tears, breast milk
    • Some are single units (monomers)
    • Circulate in the blood
    • Some are dimers - secretory IgA
    • Tear ducts, mammary glands, and mucous membranes
    • Protects body from infections in GI, respiratory, urinary, and reproductive tracts
    • Nursing newborns get IgA from mother’s milk
  30. Antibodies
    • Monomer
    • Attach to receptors on eosinophil
    • trigger release of cell-damaging molecules onto the surface of parasites (particularly worms)
    • Also, trigger mast cells and basophils to release histamine
    • Therefore, it is the antibody of allergies
  31. Antibodies
    • Membrane-bound antigen receptors on B cells
    • Like BCRs
    • Exact function or importance is unknown
  32. Describe the general function of cells and the TCR
    • T cells are very specific (like B cells)
    • Have T cell receptors (TCR) on their membranes for antigens
    • 109 types of T cells
    • T cells mature in the thymus, and react to foreign antigens presented by our own cells
  33. Cytotoxic T cells?
    • (Tc or CD8 cells)
    • directly kill infected or abnormal body cells
    • Virus-infected, bacteria-infected, protozoan infected, fungus-infected, some cancer cells and foreign cells from transplantation
  34. Helper T cells?
    • (TH or CD4 cells)
    • Type 1 helper T cells (Th1 cells) Signal cytotoxic T cells and macrophages
    • Type 2 helper T cells (Th2 cells) Communicate with B cells to activate them
    • Helper T cells secret cytokines that regulate entire immune system, adaptive & innate
  35. Regulatory T cells?
    • Also called suppressor T cells
    • Repress adaptive responses 
    • Prevent autoimmune diseases
  36. What is clonal deletion?
    • As we mentioned, both B and T cells randomly generate the shapes of their receptors on their surfaces (by rearranging certain genes to give us such variety)
    • So, every population of maturing lymphocytes includes cells with receptors that match up with normal body cells-autoantigens
    • Important that immune response not be directed against normal body cells
    • Or result is an autoimmune disease
    • 1.Body eliminates self-reactive
    • lymphocytes via clonal deletion 
    • 2.In thymus - T cells, in bone marrow - B cells
    • 3.Thymus cells express all of the body’s normal proteins, even hemoglobin, lysozyme, and muscle cell proteins, but they must be in association with MHC protein
    • 4.If T cell responds to autoantigen, it’s destroyed
    • 5.Results in self tolerance – if impaired causes?
    • 6.T cells (unlike B cells) don’t recognize epitopes unless “presented” on MHC molecules
  37. What is the function of MHC molecules?
    • The body’s cells have unique polypeptides on cell surface so can distinguish self from nonself
    • Discovered when trying to graft tissues, kept having rejection
    • Named Major Histocompatibility Complex (MHC) because of this role in tissue compatibility
    • The real role is to hold and position epitopes for “presentation” to T cells
  38. Explain the difference between Class I MHCs and Class II MHCs.
    • Class I MHCs on all cells except RBCs
    • Class II MHCs on special antigen-presenting cells – like B cells, macrophages, and dendritic cells
  39. What are cytokines?
    • Soluble regulatory proteins that act as intercellular signals to direct activities in immune responses
    • E.g., cytotoxic T cells do not respond to antigens unless they are first signaled to by cytokines
    • Cytokines are secreted by various leukocytes and affect diverse cells
  40. Cytokines
    ILs signal among leukocytes – about 35
  41. Cytokines
    Antiviral proteins that may also activate phagocytes
  42. Cytokines
    Growth factors?
    Proteins that stimulate leukocyte stem cells to divide
  43. Cytokines
    Tumor necrosis factor?
    Made by macrophages and T cells to kill tumor cells and regulate immune responses and inflammation
  44. Cytokines
    Chemotactic cytokines – signal leukocytes to move to site of inflammation or infection
  45. Describe antigen processing and presentation
    • Processing exogenous antigens
    • An APC, usually a dendritic cell, internalizes a pathogen and catabolizes its molecules, producing epitopes in a phagolysosome
    • A vesicle with MHC II molecules fuses with the phagolysosome, each epitope fuses with the antigen-binding groove of the MHC molecules
    • Vesicle then inserts these MHC-epitope complexes into the cytoplasmic membrane so that epitopes point outside