35_Immune - XXXV Defense System(Speciifiic Response XXXV...

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0B X X X X X X X X X V V V . . . D D D e e e f f f e e e n n n s s s e e e S S S y y y s s s t t t e e e m m m ( ( ( S S S p p p e e e c c c i i i f f f i i i c c c R R R e e e s s p p p o o o n n n s s s e e e ) ) ) . 43-2 INNATE IMMUNITY Recognition of traits shared by broad ranges of pathogens, using a small set of receptors •Rapid response •Recognition of traits specific to particular pathogens, using a vast array of receptors •Slower response ACQUIRED IMMUNITY Pathogens (microorganisms and viruses) Barrier defenses: Skin Mucous membranes Secretions Internal defenses: Phagocytic cells Antimicrobial proteins Inflammatory response Natural killer cells Humoral response: Antibodies defend against infection in body fluids. Cell-mediated response: Cytotoxic lymphocytes defend against infection in body cells. Recall … Humoral (antibody-mediated) immune response B cell Plasma cells Cell-mediated immune response Key Stimulates Gives rise + + + + + + + Memory B cells Antigen (1st exposure) Engulfed by Antigen- presenting cell Memory Helper T cells Helper T cell Cytotoxic T cell Memory Cytotoxic T cells Active Cytotoxic T cells Antigen (2nd exposure) Secreted antibodies Defend against extracellular pathogens by binding to antigens, thereby neutralizing pathogens or making them better targets for phagocytes and complement proteins. Defend against intracellular pathogens and cancer by binding to and lysing th infected cells or cancer cells. + ++ 3B S p e c i f r s o n t h d l Basic characteristics of the specific response are: (i) recognition of the antigen; (ii) specificity of the mounted response (only the antigen will be attacked); (iii) memory development (even after successful destruction of the invading pathogen subsequent invasions by the same agent will meet with accelerated response. The main players in the specific secondary response are lymphocytes. 1B H H H u u u m m m o o o r r r a a a l l l R R R e e e s s s p p p o o o n n n s s s e e e ± ± ± 6B A A A n n n t t t i i i b b b o o o d d d i i i e e e s s s Antibodies are proteins produced by B-cells. They are the primary bullets of the immune response. They recognize the three-dimensional structure of the antigen and bind to it.
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Antibodies are Y-shaped molecules composed of heavy chains and light chains, which are kept together by S-S bonds. F c F ab hypervariable region complement antigen receptor binding Fig. 43-11 Antigen Top view: binding surface exposed to antigen receptors Plasma membrane of infected cell Antigen Class I MHC molecule The ends of the Y-arms are the binding sites for an antigen.
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35_Immune - XXXV Defense System(Speciifiic Response XXXV...

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