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Micro ch 15 nc
| Question | Answer |
|---|---|
| immunity | the resistance developed after contracting childhood ailments adaptive and acquired |
| Acquired specific immunity | third line of defense consists of a dual system of the T and B lymphocytes during development, undergo selective process that specializes them for reacting only to one specific antigen |
| Immunocompetence | the ability of the body to react with myraid foreign substances infant is born with the potential to react to millions of different immunogens |
| immunogens | means the same as antigens |
| antigens | molecules that stimulate a response by the B and T cells protein or polysaccharide molecules on or inside all cells and viruses |
| T/F our own antigens do not usually evoke a response from our own immune system | true |
| pathogen-associated molecular patterns (PAMPs) | stimulate response by phagocytic cells during an innate defense response |
| comparison of antigens and PAMPs | PAMPs stimulate a nonspecific response; antigens are highly ind and stimulate specific immunity two shared characteristics: 1. are "parts" of foreign cells (microbes) 2. provoke a defense rxn from the host |
| Two features of the third line of defense are: | specificity memory |
| Example of Specificity | antibodies produced during infection against chickenpox virus will function against only that virus and not against the measles virus |
| Memory | the rapid mobilization of lymphocytes that have been programmed to "recall" their first engagement w/invader and rush to the attack once again |
| Stages of immunologic development and interaction | 1. Lymphocyte development and differentiation 2. The presentation of antigens 3. The challenge of B and T lymphocytes by antigens 4. B lymphocytes and the production and activities of antibodies 5. T lymphocyte responses |
| dual lymphocyte system | development begins in embryonic yolk sac and shift to liver and bone marrow diverge into two distinct types: the Tcell and Bcell |
| where does each cell mature? | T-cells mature in the thymus B-cells mature in the bone marrow |
| what occurs during maturation? | process commits each cell to one specificity |
| Entrance and presentation of antigens and clonal selection | phagocytes migrate to site of infection; ingest the antigen; migrate to the nearest lymphoid organ process and present antigen to T lympohcytes pathogen drain into the lymph nodes---activates the B cells most B cells need T helper cells |
| Activation of lymphocytes and clonal expansion | multipication of a particular lymphocyte create a clone some are memory cells that will ensure future reactiveness against that antigen this is the stage where responses of the T cell and B cell depart |
| plasma cells | progeny of dividing B cell clone programmed to synthesize and secrete antibodies into tissue fluid and blood |
| what does an antigen do? | antibody attaches to an antigen, narks it for destruction and neutralization |
| Why are B cells considered humoral immunity? | humoral immunity because secreted antibody molecules circulate freely in the tissue fluids, lymph, and blood |
| Cell-mediated immunity (CMI) | How T cells respond to antigen when activated by antigen,T cell gives rise to 1 of 3 diff. progeny TH1 cells activate macrophages&help activate Tc cells TH2 cells assist B cells Tc cells lead to the destruction of infected host cells & foreign cells |
| T/F T-cells secrete antibodies. | do not produce antibodies secrete cytokines that help destroy pathogens or regulate immune response |
| Major functions of receptors | a. Attach to nonself molecules b. Binding to cell surface receptors that indicate self, such as MHC molecules c. Receiving and transmitting chemical messages to coordinate the response d. Aiding in cellular development |
| Major histocompatibility complex (MHC) | genes that code for human cell receptors found on all cells except RBCs |
| human leukocyte antigen (HLA) system | white blood cell markers plays a vital role in recognition of self by the immune system and in rejection of foreign cells |
| Three MHC classes | class MHC I, II, and III |
| class I MHC | codes for markers that display unique characteristics of self and allow regulation of immune rxns each human inherits a particular combination of genes; necessitates testing for MHC antigen when blood transfused or organs transplanted |
| class II MHC | code for immune regulatory receptors found on macrophages, dendrite cells, and B cells involved in presenting antigens to T cells during cooperative immune rxn |
| class III MHC | genes encode proteins involved with complement system among others |
| Lymphocyte receptors and specificity to antigen | B cells have receptors that bind to antigens T cells have receptors that bind processed antigens plus MHC molecules on cells that present antigens to them |
| clonal selection theory and lymphocyte development | Lymphocyte specificity is pre-programmed Each type of lymphocyte has a single specificity |
| proliferate stage | cells give rise to a line of specific lymphocytes with the same specificity known as clones |
| clonal selection and expansion | requires stimulation by an antigen antigen enters immune surveillance system, encounters specific lymphocytes ready to recoginize it |
| Tolerance to self principle | Clones that react to self are destroyed is known as clonal deletion |
| auto immunity | some diseases are thought to be by the loss of the immune tolerance through the survival of certain "forbidden clones" or failure of other systems |
| immunoglobulin molecule (Ig) | specific B-cell receptor large glycoprotein molecules that serve as the antigen receptors of B cells and antibodies |
| Ig structure | composite of four polypeptide chains pair of identical heavy (H) chains and a pair of identical light (L) chains one light is bonded to one H chain; two H are bonded to one another with disulfide bonds -- symmetrical Y-shaped arrangement |
| Antigen binding site | end of forks formed by the light and heavy chain contain pockets |
| Variable region | cause high variablilty diff amino acid compositions |
| Constant region | amino acid content is relatively same for all |
| T-cell receptors | similar to B cells--have variable and constant region and antigen biding site relatively small and never secreted (unlike Ig) |
| B-cell maturation | Bone marrow sites that harbor stromal cells circulate to spleen, lymph nodes, and GALT--here they will adhere to specific molecules |
| stromal cells | huge cell nurture the lymphocyte stem cells and provide chemical signals to initiate B-cell development |
| T-cell maturation | Directed by thymus Mature T cells express CD4 or CD8 coreceptors |
| CD4 | binds to MHC class II and is expressed on T helper cells |
| CD8 | found on cytotoxic T cells and binds to MHC class I molecules migrate to specific T cell areas of the spleen and lymph nodes |
| processing of antigens | to be percieved as an antigen, a substance must meet certain requirements in foreigness, shape, size, and accessibility |
| antigenicity | property of behaving as an antigen |
| antigens or immunogens | both refer to as substances that can elicit an immune response |
| materials that serve as antigens | Proteins and polypeptides(enzymes, cell surfaces, hormones, exotoxins) Lipoproteins(cell membrane) Glycoproteins(blood cell marker) Nucleoproteins(DNA complexed to protein) Polysaccharides(bacterial capsules) |
| effects of molecular shape and size | must be large enough to "catch the attention" of the surveillance cells |
| epiotope | portion of antigen molecule that is recognized by lymphocytes primary signal that the molecule is foreign |
| haptens | partial antigens small foreign molecules that consist only of a determinant group and are too small by themselves to elicit an immune response link to a larger molecule to develop antigenicity (many combine w/ serum proteins) |
| alloantigens | cell surface markers and molecules that occur in some members of the same species but not in others basis for ind blood groups and major histocompatibility profile responsible for incompatibilities that occur in blood transfusion or organ grafting |
| superantigens | a group of immunogens that are potent stimuli for T cells |
| allergens | antigen hat evoke allergic reactions |
| antigen-processing cells (APCs) | resen foreign antigens to T cells to be recognized as foreign |
| different cells that serve as APCs | macrophages B cells dendritic cells |
| dendritic cells | engulf the antigen and modifiy it so that it will be more immunogenic and recognizable to T lymphocytes |
| T-cell dependent antigens | require recognition steps between the APC, antigen, and lympohcytes |
| interleukin-2 | a growth factor for the T helper cells and cytotoxic T cells |
| T-cell indepedent antigens | simple molecules (carbs) with many repeating and invariable determinant groups |
| activation of B cells | requires a series of events: 1. Clonal selection and binding of antigen 2. Antigen processing and presentation 3. B-cell/T-cell recognition and cooperation 4. B-cell activation 5. Clonal expansion 6. Antibody production and secretion |
| Clonal selection and binding of antigen | precommitted B cell of a particular clonal specificity binds the antigen on its Ig receptors |
| Antigen processing and presentation | antigen is engulfed by the B cell and degraded into small peptide determinants antigen is then bound to MHC II receptors on the surface of the B cell |
| B-cell/T-cell recognition and cooperation | MHC/Ag receptor is recognized and bound by a T helper cell B cellrecieves chemical signals from macrophages and T cells |
| B-cell activation | chemical signals triggers B cell activation activated B cell undergoes an inc in DNA synthesis, organelle bulk, and overall size in preperation for entering cell cycle and dividing |
| Clonal expansion | B cell multiples through mitotic division; produces a large population of identical daughter cells memory cells-not fully differentiated expansion of clone size;accounts for increased memory response plasma cells are the most numerous progeny |
| Antibody production and secretion | primary action of plasma cells is to secrete into the surrounding tissues copious amounts of antibodies with the same specificity as the original receptor plasma cells deteriorate after they have synthesized antibodies |
| structure of immunoglobulins | contains four polypeptide chains connected by disulfide bonds |
| Most common class is Ig | IgG |
| Antigen-binding fragment | two "arms" that bind the antigen abbreviated FAb fragment the amino-terminal end folds into a groove that will accommodate one epitope |
| Crystallizable fragment | remaining portion of the fragment called because it was first to be crystallized in pure form abbreviated as Fc fragment also involved in binding to various cells and molecules of the immune system |
| site of attachment between the two fragments | allows swiveling of the FAb fragments; can change their angle to accommodate nearby antigen sites that vary slightly in distance and position |
| function of the FAb | Opsonization by opsonin Agglutination by antibodies Neutralizing antibodies Antitoxins |
| Opsonization by opsonin | a process in which microorganisms and other particles are coated with specific antibodies so that they will become more readily recognized by phagocytes (dispose of them) |
| Agglutination by antibodies | particles into large clumps render microbes immobile and enhances their phagocytosis |
| Neutralizing antibodies | antibodies fill the surface receptors on a virus or the active site on a microbial enzyme to prevent it from attaching normally |
| Antitoxins | a special type of antibody that neutralizes bacterial exotoxins |
| Functions of the Fc fragment | function depends on the role that fragment plays in opsonization, fragment is exposed for phagocytes can also release cytokines size and amino acid composition also determne antibody's permability, it distribution in the body, and its class |
| Isotypes | structural and functional classes of immunoglobulins primarily due to Fc fragments |
| IgG | most prevalent class monomer produced by plasma cells in primary response and by memory cells in secondary response neutralizes toxins, opsonizes, and fixes complement only antibody capable of crossing placenta |
| IgA | two forms: moomer that circulates in small amounts in the blood and dimer that role in mucous and serous secretions found in blood, serum and mucous secretions including saliva, tears, etc. |
| IgM | a pentamer molecule; 10 binding sites gives it a tremendous capacity for binding antigen |
| IgE | involved in allergic reactions and parasitic worms; basophils and mast cell activation--stimulate inflammation causes anaphylaxis, asthma reactions |
| antiserum | serum containing specific antibodies |
| gamma globulin | composed primarily of IgG |
| beta and alpha-2 globulins | mixture of IgG, IgA, IgM |
| cell-mediated immunity | the type of immune response brought about by t cells, such as cytotoxic and helper effects |
| function of T cells | make other T cells, B cells, and phagocytoes |
| T helper cell | CD4 is receptor regulates immune reactions to antigens activates macrophages secrete interleukin-2 most prevalent type of Tcell in the blood and lymphoid organs |
| how TH cells activate macrophages? | directly by receptor contact indirectly by relasing cytokines |
| cytotoxic T cells | CD8 is receptor cells that kill other cells |
| cytotoxicity | the capacity of certain T cells to kill a specific target cell |
| how is a killer T cell activated? | it must recognize a foreign peptide complexed with self MHC-I |
| how does killer Tcell kill target cell? | secretes perforins and granzymes |
| perforins | proteins that can punch holes in the membranes of target cells cause ions to leak out of the target cells and create a passageway for granzymes to enter |
| granzymes | enzymes tat attack protein of target cells |
| apoptosis | target cell death |
| target cells that Tc cells can destroy | virally infected cells cancer cells cells from other animals and humans |
| natural killer cells | type of lymphocyte related to T cells that lack specificity for antigens circulate spleen,blood, and lungs first cells to attack cancer and virus-infected cells |
| T/F NK cells are part of the specific cell-mediated immunity. | false |
| categories of acquired immunity | natural:active and passive artificial:active and passive |
| natural immunity | acquired through the normal life experiences of a human and is not induced through medical means |
| artificial immunity | produced purposefully through medical procedures--also called immunization |
| active immunity | the consequence of a person developing the own immune response to a microbe |
| passive immunity | the consequence of one person recieving preformed immunity made by another person |
| active immunity characteristics | 1. an essential attribute of immunocompetent ind 2. it creates a memory that renders the person ready for quick action upon reexposure to that same antigen 3. requires several days to develop 4. it lasts for a relaively long time, sometimes for life |
| passive immunity characteristics | 1. lack of memory for the original antigen 2. lack of production of new antibodies against that disease 3. immediate onset of protection 4. short-term effectiveness |
| Natural active immunity | Getting the infection after infection, person has a period of resistance against reinfection time of period varies according to the disease childhood viral infections: measles,mumps, rubella are akmost lifetime |
| Natural passive immunity | Mother to child prenatal or postnatal fetal life,IgG antibodies can cross the placenta;antibodies for tetanus,diptheria, pertussis,other viruses only protect first few months outside womb milk-borne antibodies provide special intestinal protection |
| immunization | artificial immunity any clinical process that produces immunity in a subjects also called immunoprophylaxis bc used to give advance protection against infection |
| active immunization | a person is administered antigen vaccination |
| passive immunization | a person is given antibodies a type of immune therapy |
| vaccination | exposes a person to a specially prepared microbial (antigenic) stimulus, which then triggers the immune system to produce antibodies and lymphocytes to protect the person upon future exposure to the microbe |
| artificial passive immunization | patient at risk for acquiring a particular infection is administered a preperation that contains specific antibodies agaisnt that infectious agent horse serum donated human blood |
| purpose of vaccination | exposes to antigen but not pathogen basic principle to stimulate primary and secondary response that primes the immune system for future exposure to a virus |
| vaccine preparation | 1. kill whole cells or inactivated viruses 2. live, attenuated cells or viruses 3. antigenic molecules derived from bacterial cells or viruses 4. genetically engineered or microbial antigens |
| qualities of an effective vaccine | have little adverse effects;cause no harm protect against exposure of pathogen stimulate both Bcell(antibody)&Tcell(cell-mediated)response have long-term effects(memory) not require many doses or boosters inexpensive,long shelf life,easily administer |
| killed or inactive vaccines | cultivating desired strain(s) of bacterium/virus & treating with formalin,radiation,heat,or other agent that doesnt destroy antigenicity ex polio&influenza bc microbe doesnt multiply,killed vaccines require larger dose and more boosters to be effective |
| attenuation | any process that substantially lessens or negates the virulence or viruses or bacteria achieved by modifying the growth conditions in a way that eliminates virulence factors ex TB, measles, mumps rubella |
| advantage for live preperations | viable microorganisms can multiply and produce infection like the natural organism; they confer long-lasting protection; require fewer doses and boosters; particularly effective at inducing cell-mediated immunity |
| disadvantage for live preparations | they require special storage facilities, can be transmitted to other people, and can conceivably mutate back to a virulent strain |
Created by:
marosado10
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