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Flashcards in Adaptive immunity Deck (35):
1

adaptive (acquired, specific) immune response

-acts against a specific intruder
-acquired when a pathogen is encountered for the first time
-has memory:
*responds more vigorously the second time a particular pathogen is encountered

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adaptive is divided into two branches

-humoral (antibody mediated) immunity
-cellular (cell mediated) immunity

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antibodies are also called (Ab)

immunoglobulins (Ig)

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glycoproteins are composed of 4 subunits

-2 identical heavy chains
-2 identical light chains

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each antibody has..

-2 identical antigen binding sites (Fab)
-one Fc site- can interact with other components o the immune system

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5 classes of antibodies

-IgG
-IgM
-IgA
-IgD
-IgE

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Immunoglobulin G (IgG)

-monomer
-most abundant antibody in blood and tissues
-most important for combating a pathogen

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IgM

-a pentamer
-first antibody made when a new antigen is encountered
-excellent at agglutination
-does not leave blood and enter tissues

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IgA

-a dimer
-secreted into saliva, tears, mucous
-helps to protect mucosal surfaces

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IgD

-monomer
-found on the surface of B cells
-plays a role in activating B cells to respond against an antigen
-diamond antigens instead of triangle

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IgE

-monomer
-found on the surface of mast cells and basophils
-causes them to release granules of histamine
-trigers allergic response
-extra long light chains

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five major functions of antibodies

1. neutralization
2.opsonization
3.agglutination
4.antibody mediated cytotoxicity
5.complement activation

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neutralization

-Ab stick to antigens on a foreign particle and block attachment sites
-stops bacteria, viruses and toxins from entering host cells

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Opsonization

-Ab stick to a pathogen's surface and flag down phagocytes
-phagocyte interacts with the Fc region and engulfs the pathogen
-greatly increases rate of phagocytosis

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Agglutination

-Ab can stick to two identical antigens
-bridges particles together in clumps
-can be phagocytized more easily

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antibody mediated cytotoxicity

-Ab binds to antigen on the surface of a parasite
-Fc can interact with eosinophils
-eosinophils release enzymes and reactive oxygen intermediates to attack the parasite

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Complement activation

-Ab found to a bacterial cell can activate complement
-A set of proteins in the blood that assist other components of the immune system
-classical pathways of complement activation
-results in the membrane attack complex (MAC)
-insert into bacterial membranes
-forms a pore
-cell leaks and dies

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adaptive response properties

-acquired
-specific
-memory
-tolerance

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acquired

-a pathogen must be encountered before the adaptive immune response is mounted

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specific

can mount a directed attack against a specific pathogen
-immunity to one pathogen does not confer immunity to another

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memory

once a specific pathogen has ben encountered immune system cells multiply and produces long living memory cells
-if the pathogen is encountered again, the memory cells will mount a faster, stronger response

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tolerance

-inability to mount an adaptive immune response against self antigens
-immune system cells that recognize self-antigens are destroyed during development

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primary response

-the first time a new pathogen is encountered, the adaptive immune response is weak
-the major result is the production of immunologic memory

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secondary respond

the next time that pathogen is encountered memory cells are ready to respond
-response can be so quick that the pathogen is unable to cause disease
ie. immunity

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immunogen

any foreign particle that can induce an adaptive immune response
-normally large molecules- proteins, polysaccharides, some lipids

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antigen

any substance that can react with antibodies or receptors on adaptive immune system cells

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antibody

protein made by the immune system that can bind to, and inactivate foreign antigens

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epitiope

(or antigenic determinant)
-the actual part of the antigen that can bind to an antibody
-the more epitopes on an antigen, the more immunogenic it will be
-and the more diverse population of antibodies can be generated against it

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hapten

low molecular weight compound too small to be immunogenic on its own, but can be highly antigenic

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hapten example

penicillin is small and non-immunogenic on tis own
-can bind to proteins in the blood forming a strong immunogen
-antibodies are formed against it-leading to an allergic response

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cells of the adaptive immune system

-b lymphocytes (B cells)
-T lymphocytes (T cells)

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B cells

-antibody producing cells
-involved in the humoral immune response

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T cells

-T-cytotoxic cells (Tc cells)
-T-helper cells (Th cells)

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Tc cells

-destroy abnormal body cells (ex. cells infected by viruses)
-involved in cel mediated response

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Th cells

Help B and Tc cells prepare for an immune response
-humoral and cell mediated