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18 Cards in this Set
- Front
- Back
Differences between innate and acquired immunity?
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a. Innate
-Physicial and chemical barriers -Phagocytic cells (neutrophils/macrophages), large granular lymphocytes -Cells in blood/tissues -NOT affected by prior exposure b. Acquired immunity -last line of defense -we react to foreign substance (antigen; molecular epitopes are small peptides) |
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List 3 major characteristics of an immune response (acquired immunity)
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i. Specific: response against inciting antigen only
ii. Adaptive: no response until antigen encountered iii. Memory: after 1st encounter with antigen, organism is immune (later responses occur faster and stronger, specificity maintained) |
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Describe basic antibody structure
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-Large glycoprotein: 2 heavy chains, 2 light chains
-2 antigen-binding domains: include 1 heavy, 1 light chain -Fc region: 2 heavy chains (binds to cells with Fc receptors, eg: neutrophils, macrophages) |
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Describe unique functional feature of IgA antibodies and IgE antibodies
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a. IgA: prevents invasion of mucosal surfaces
b. IgE: Cause degranulation of mast cells |
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2 Characteristics of naive lymphocytes
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a. Small
b. Immunocompetent *specificity of cellular response determined by rxn with 1 antigen. |
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Describe major types of T lymphocytes
*cell-mediated immunity |
1. Cytotoxic T cells: kill target directly when receptor bound (imp for virus-infected cells)
2. Helper T cells: secrete cytokines (paracrine mech), recruit/activate other cells a. Th1: Promote Cytotoxic t cell activation., recruit macrophage ect to generate inflammation (eg. Inflammatory T cell) b. Th2: promote B cell activation, development of humoral immunity 3. Regulatory T cells (Treg): known as suppressor T cells (Ts), produce cytokines that inhibit immune responses |
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Define 3 phases of an immune response
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I. Cognitive phase
-B cells: receptor is antibody, all on one cell have same specificity -T cells: receptor is not antibody, but all on one cell have same specificity (recognizes antigen by its binding pattern) II. Activation phase: effectors produced in lymphoid organs. Clonality. III. Effector phase: Antibodies and activated Tc and Th1 cells clear antigen. In periphery. Specific antigen recognition. |
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Define concept of clonality
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Expansion by proliferation of clone with single specificity
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Compare antigen binding by B cells and T cells
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a. T-cells: Antigen-presenting cells (APC; dendritic cells, related to macrophages,family members present in connective tissue of most organs/stratified epithelia-Langerhans cells, migrate to lymphoid tissues via lymphatic drainage) present antigen to naitive T cells
b. B cells: occurs w/o APC, B cell receptor is antibody. |
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Compare requirements for activation of B and T cells
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a. T cells: APC, TH1 cell/cytokines
b. B cells: activated Th2 cell/its cytokines, differentiate into plasma cells. |
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Two primary/central
Four secondary/peripheral lymphoid organs (antigen response generated) |
a. Thymus (naive T cells) and bone marrow (naive B cells)
b. Lymph node, spleen, mucosal lymphoid tissue (adenoid, tonsil, appendix, Peyer's patches) **objectives specify four organs, more in syllabus |
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Define/why necessary?
a. Lymphocyte specificity b. lymphocyte recirculation |
a. Lymphocyte reactive to 1 antigen
-Problems: few lymphocytes reactive to given antigen, antigens can enter at many sites. b. Naive lymphocytes randomly circulate among secondary organs to encounter antigen -to address problems above |
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3 components of secondary lymphoid organs necessary to develop immune response (leading to antibody production)
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1. High [] APCs
2. Antigen accumulate here 3. Filtration pattern/lymphocyte recirculation (spleen filters blood, lymph nodes filter lymph, material taken across mucosal surfaces) |
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Compare two regions lymph node cortex (structure/function)
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A. Outer cortex: B cells accumulate/activated here.
*Round follicles (some T cells) *Secondary follicles (pale germinal central). B cell activation here. B. Deep cortex/Parafollicular area *APC's activate T cells. |
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Compare primary location/function in lymph node
a. Macrophage b. Dendritic cell |
a. Medullary cords (filtration of lymph)
b. Parafollicular region of cortex (antigen presentation to naive T cells) |
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2 ways lymphocytes can enter a lymph node?
How do antigens enter lymph node? |
1. Through postcapillary venules in the deep cortex by receptor-mediated movement
2. Via afferent lymphatics from peripheral tissue. Antigens: 1. Enter via lymph flow through afferents or from dendritic cells that have captured antigens and settle in cortical tissue |
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Lymph flow pattern lymph node vs. blood flow
*compartments are entirely separate |
Lymph flow: afferent lymphatic, subscapular sinus, intermediate sinus (cortex, then medullary cord), medullary sinus, efferent lymphatic (at hilum)
Blood flow: Artery, arterioles, capillaries (in cortex), high endothelial venules, small vein, vein (enter/exit at hilum) |
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Compare structure
a. Lymph node b. Mucosal-associated lymphoid tissues (tonsils/Peyer's patches) |
a. Stroma: Capsule and trabeculae (type I collagen/fibroblasts), remainder (except blood vessels) laced with reticular fibers (Type III collagen)
Regions: outer cortex, inner medulla b. Peyer's patch: follicles and non-follicular area, NO medulla. *efferent, but NO afferent lymphatics *Uptake: -M cells (intestinal epi): transport antigens to lymphoid compartments -Dendritic cells (lamina propria): send extensions to epithlium. |