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Flashcards in ch 8 - The Immune System Deck (59)
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1

Innate immunity

composed of defenses that are always active against infection but lack ability to target specific invaders over others; also called nonspecific immunity. antimicrobial molecules and various phagocytes - some destroy and some trigger more immune cell response

2

adaptive immunity

defenses that target a specific pathogen; also called specific immunity; slower to act but can mount a quicker attack in subsequent infections of same pathogen; T-cells which help activate B-cells or other T-cells or directly attack infected cells, and B-cells which secrete antibody molecules that bind to antigens. Both spawn memory cells that kill quicker next time

3

B-cells

cell produced in bone marrow, stored and activated in spleen (and lymph nodes). Turn into plasma cells to produce antibodies - adaptive immunity

4

humoral immunity

division of adaptive immunity; antibodies dissolve and act in blood rather than within cells

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T-cells

adaptive immune cell produced in bone marrow and matured in thymus; kill virally infected cells

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cell-mediated immunity

T-cells are agents of this because they coordinate the immune system and directly kill virally infected cells

7

lymph nodes

major component of the lymphatic system that provides a place for immune cells to communicate and mount an attack; also a site of B-cell activation

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gut-associated lymphoid tissue (GALT)

immune tissue found close to digestive system; includes tonsils, adenoids in head; Peyer's patches in small intestines; and lymphoid aggregates in the appendix

9

integument

skin

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defensins

antibacterial enzymes found in skin

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complement system

consists of proteins in the blood that act as a nonspecific (even though it is associated with antibodies) defense against bacteria by punching holes in them and making them more osmotically unstable

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classical pathway

means of activating complement (system) that requires the binding of an antibody to a pathogen

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alternative pathway

means of activating complement (system) that does not require antibodies

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interferons

proteins produced by cells that have been infected with viruses that prevent viral replication and dispersion; cause nearby cells to decrease production of viral and cellular proteins and decrease permeability of these cells making viral infection more difficult; upregulate MHC (major histocompatibility complex) class I and II molecules resulting in increased antigen presentation and better detection of infected cells by the immune system

15

macrophages

type of agranulocyte which resides in tissues; derive from blood-borne monocytes and can beome a resident population in a tissue (more permanent); phagocytizes invader through endocytosis, digests using enzymes and presents pieces to other cells using MHC

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MHC (major histocompatibility complex)

used by macrophages, bind to a pathogenic peptide (antigen) and carries it to the cell surface where it can be recognized by adaptive immune system; come in two main classes (I and II)

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cytokines

chemical substances released by macrophages that stimulate inflammation and recruit additional immune cells to the area

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MHC class I

displayed by all nucleated cells in the body; any protein in cell can be loaded onto it and presented on the surface of the cell which allows immune system to monitor the health of these cells and to detect if the cells have been infected. Infected cells would be expected to display a nonself (unfamiliar) protein; called endogenous pathway

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MHC class II

displayed only by professional antigen-presenting cells (dendritic cells in skin, macrophages, some B-cells, certain activated epithelial cells)

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antigen

substance - usually pathogenic protein - that can be targeted by an antibody

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exogenous pathway

pathway originating outside the cell such as antigens

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pattern recognition receptors

special receptors on macrophages and dendrite cells able to recognize the category of invader (bacterium, virus, fungus, parasite) which allows production of appropriate cytokines to recruit immune cells which target particular groups of pathogens

23

Natural killer (NK) cells

type of nonspecific lymphocyte able to detect downregulation of MHC and induce apoptosis in virally infected cells; also protect against growth of cancer as cancer also downregulates MHC

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Neutrophils

ganulocytes; most populous leukocyte in blood, very short-lived; phagocytic and target bacteria; follow bacteria using chemotaxis (sensing of certain products given off by bacteria) and follow back to bacterium and detect bacteria once they are opsonized (marked with an antibody from a B-cell). dead neutrophils form pus

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Eosinophils

granulocytes containing bright red-orange granules and are involved in allergic rxns and invasive parasitic infections. release large amounts of histamine (inflammatory mediator) which results in vasodilation and increased leakiness of blood vessels allowing additional immune cells to move out of the bloodstream and into the tissue.

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basophils

granulocytes containing large purple granules; involved in allergic responses. least populous leukocyte in bloodstream under norm conditions; closely related to mast cells but with smaller granules; exist in tissues, mucosa and epithelium

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Humoral immunity

form of adaptive immunity; primarily B-cells; involves production of antibodies specific to antigens of the invading microbe; may take up to a week to become fully effective

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immunoglobulins [Ig]

another term for antibodies; can float freely in blood, chyle (lymph) or air or be present on surface of cell

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possible functions of antibodies secreted into body fluids

1. bind to specific antigen, attract other leukocytes and phagocitze antigens immediately (osponization), 2. cause pathogens to clump together (agglutinate) forming large insoluble complexes to be phagocytized. 3. block the ability of a pathogen to invade tissues neutralizing it.

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function of cell-surface antibodies

binding of antigen to a B-cell causes activation of that cell. on surface of mast cell binding causes degranulation (exocytosis of granule contents), allowing release of histamine and causing an inflammatory allergic rxn