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Key Terms Chapter 21: The Lymphatic and Immune System

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    active immunity
    immunity developed from an individual’s own immune system
    acute inflammation
    inflammation occurring for a limited time period; rapidly developing
    adaptive immune response
    relatively slow but very specific and effective immune response controlled by lymphocytes
    afferent lymphatic vessels
    lead into a lymph node
    antigen-specific protein secreted by plasma cells; immunoglobulin
    molecule recognized by the receptors of B and T lymphocytes
    antigen presentation
    binding of processed antigen to the protein-binding cleft of a major histocompatibility complex molecule
    antigen processing
    internalization and digestion of antigen in an antigen-presenting cell
    antigen receptor
    two-chain receptor by which lymphocytes recognize antigen
    antigenic determinant
    (also, epitope) one of the chemical groups recognized by a single type of lymphocyte antigen receptor
    B cells
    lymphocytes that act by differentiating into an antibody-secreting plasma cell
    barrier defenses
    antipathogen defenses deriving from a barrier that physically prevents pathogens from entering the body to establish an infection
    bone marrow
    tissue found inside bones; the site of all blood cell differentiation and maturation of B lymphocytes
    bronchus-associated lymphoid tissue (BALT)
    lymphoid nodule associated with the respiratory tract
    central tolerance
    B cell tolerance induced in immature B cells of the bone marrow
    soluble, long-range, cell-to-cell communication molecule
    chronic inflammation
    inflammation occurring for long periods of time
    lipid-rich lymph inside the lymphatic capillaries of the small intestine
    cisterna chyli
    bag-like vessel that forms the beginning of the thoracic duct
    class switching
    ability of B cells to change the class of antibody they produce without altering the specificity for antigen
    clonal anergy
    process whereby B cells that react to soluble antigens in bone marrow are made nonfunctional
    clonal deletion
    removal of self-reactive B cells by inducing apoptosis
    clonal expansion
    growth of a clone of selected lymphocytes
    clonal selection
    stimulating growth of lymphocytes that have specific receptors
    group of lymphocytes sharing the same antigen receptor
    enzymatic cascade of constitutive blood proteins that have antipathogen effects, including the direct killing of bacteria
    constant region domain
    part of a lymphocyte antigen receptor that does not vary much between different receptor types
    soluble, short-range, cell-to-cell communication molecule
    cytotoxic T cells (Tc)
    T lymphocytes with the ability to induce apoptosis in target cells
    delayed hypersensitivity
    (type IV) T cell-mediated immune response against pathogens infiltrating interstitial tissues, causing cellular infiltrate
    early induced immune response
    includes antimicrobial proteins stimulated during the first several days of an infection
    effector T cells
    immune cells with a direct, adverse effect on a pathogen
    efferent lymphatic vessels
    lead out of a lymph node
    erythroblastosis fetalis
    disease of Rh factor-positive newborns in Rh-negative mothers with multiple Rh-positive children; resulting from the action of maternal antibodies against fetal blood
    fas ligand
    molecule expressed on cytotoxic T cells and NK cells that binds to the fas molecule on a target cell and induces it do undergo apoptosis
    Fc region
    in an antibody molecule, the site where the two termini of the heavy chains come together; many cells have receptors for this portion of the antibody, adding functionality to these molecules
    germinal centers
    clusters of rapidly proliferating B cells found in secondary lymphoid tissues
    graft-versus-host disease
    in bone marrow transplants; occurs when the transplanted cells mount an immune response against the recipient
    apoptosis-inducing substance contained in granules of NK cells and cytotoxic T cells
    heavy chain
    larger protein chain of an antibody
    helper T cells (Th)
    T cells that secrete cytokines to enhance other immune responses, involved in activation of both B and T cell lymphocytes
    high endothelial venules
    vessels containing unique endothelial cells specialized to allow migration of lymphocytes from the blood to the lymph node
    vasoactive mediator in granules of mast cells and is the primary cause of allergies and anaphylactic shock
    antibody whose dimer is secreted by exocrine glands, is especially effective against digestive and respiratory pathogens, and can pass immunity to an infant through breastfeeding
    class of antibody whose only known function is as a receptor on naive B cells; important in B cell activation
    antibody that binds to mast cells and causes antigen-specific degranulation during an allergic response
    main blood antibody of late primary and early secondary responses; passed from mother to unborn child via placenta
    antibody whose monomer is a surface receptor of naive B cells; the pentamer is the first antibody made blood plasma during primary responses
    immediate hypersensitivity
    (type I) IgE-mediated mast cell degranulation caused by crosslinking of surface IgE by antigen
    immune system
    series of barriers, cells, and soluble mediators that combine to response to infections of the body with pathogenic organisms
    protein antibody; occurs as one of five main classes
    immunological memory
    ability of the adaptive immune response to mount a stronger and faster immune response upon re-exposure to a pathogen
    basic innate immune response characterized by heat, redness, pain, and swelling
    innate immune response
    rapid but relatively nonspecific immune response
    early induced proteins made in virally infected cells that cause nearby cells to make antiviral proteins
    light chain
    small protein chain of an antibody
    fluid contained within the lymphatic system
    lymph node
    one of the bean-shaped organs found associated with the lymphatic vessels
    lymphatic capillaries
    smallest of the lymphatic vessels and the origin of lymph flow
    lymphatic system
    network of lymphatic vessels, lymph nodes, and ducts that carries lymph from the tissues and back to the bloodstream.
    lymphatic trunks
    large lymphatics that collect lymph from smaller lymphatic vessels and empties into the blood via lymphatic ducts
    white blood cells characterized by a large nucleus and small rim of cytoplasm
    lymphoid nodules
    unencapsulated patches of lymphoid tissue found throughout the body
    ameboid phagocyte found in several tissues throughout the body
    macrophage oxidative metabolism
    metabolism turned on in macrophages by T cell signals that help destroy intracellular bacteria
    major histocompatibility complex (MHC)
    gene cluster whose proteins present antigens to T cells
    mast cell
    cell found in the skin and the lining of body cells that contains cytoplasmic granules with vasoactive mediators such as histamine
    memory T cells
    long-lived immune cell reserved for future exposure to a pathogen
    MHC class I
    found on most cells of the body, it binds to the CD8 molecule on T cells
    MHC class II
    found on macrophages, dendritic cells, and B cells, it binds to CD4 molecules on T cells
    MHC polygeny
    multiple MHC genes and their proteins found in body cells
    MHC polymorphism
    multiple alleles for each individual MHC locus
    precursor to macrophages and dendritic cells seen in the blood
    mucosa-associated lymphoid tissue (MALT)
    lymphoid nodule associated with the mucosa
    naïve lymphocyte
    mature B or T cell that has not yet encountered antigen for the first time
    natural killer cell (NK)
    cytotoxic lymphocyte of innate immune response
    negative selection
    selection against thymocytes in the thymus that react with self-antigen
    inactivation of a virus by the binding of specific antibody
    phagocytic white blood cell recruited from the bloodstream to the site of infection via the bloodstream
    enhancement of phagocytosis by the binding of antibody or antimicrobial protein
    passive immunity
    transfer of immunity to a pathogen to an individual that lacks immunity to this pathogen usually by the injection of antibodies
    pattern recognition receptor (PRR)
    leukocyte receptor that binds to specific cell wall components of different bacterial species
    molecule in NK cell and cytotoxic T cell granules that form pores in the membrane of a target cell
    peripheral tolerance
    mature B cell made tolerant by lack of T cell help
    movement of material from the outside to the inside of the cells via vesicles made from invaginations of the plasma membrane
    plasma cell
    differentiated B cell that is actively secreting antibody
    polyclonal response
    response by multiple clones to a complex antigen with many determinants
    positive selection
    selection of thymocytes within the thymus that interact with self, but not non-self, MHC molecules
    primary adaptive response
    immune system’s response to the first exposure to a pathogen
    primary lymphoid organ
    site where lymphocytes mature and proliferate; red bone marrow and thymus gland
    study of the connections between the immune, nervous, and endocrine systems
    regulatory T cells (Treg)
    (also, suppressor T cells) class of CD4 T cells that regulates other T cell responses
    right lymphatic duct
    drains lymph fluid from the upper right side of body into the right subclavian vein
    secondary adaptive response
    immune response observed upon re-exposure to a pathogen, which is stronger and faster than a primary response
    secondary lymphoid organs
    sites where lymphocytes mount adaptive immune responses; examples include lymph nodes and spleen
    first exposure to an antigen
    clearance of pathogen in the serum and the simultaneous rise of serum antibody
    severe combined immunodeficiency disease (SCID)
    genetic mutation that affects both T cell and B cell arms of the immune response
    secondary lymphoid organ that filters pathogens from the blood (white pulp) and removes degenerating or damaged blood cells (red pulp)
    T cell
    lymphocyte that acts by secreting molecules that regulate the immune system or by causing the destruction of foreign cells, viruses, and cancer cells
    T cell tolerance
    process during T cell differentiation where most T cells that recognize antigens from one’s own body are destroyed
    T cell-dependent antigen
    antigen that binds to B cells, which requires signals from T cells to make antibody
    T cell-independent antigen
    binds to B cells, which do not require signals from T cells to make antibody
    Th1 cells
    cells that secrete cytokines that enhance the activity of macrophages and other cells
    Th2 cells
    cells that secrete cytokines that induce B cells to differentiate into antibody-secreting plasma cells
    thoracic duct
    large duct that drains lymph from the lower limbs, left thorax, left upper limb, and the left side of the head
    immature T cell found in the thymus
    primary lymphoid organ; where T lymphocytes proliferate and mature
    tissue typing
    typing of MHC molecules between a recipient and donor for use in a potential transplantation procedure
    lymphoid nodules associated with the nasopharynx
    type I hypersensitivity
    immediate response mediated by mast cell degranulation caused by the crosslinking of the antigen-specific IgE molecules on the mast cell surface
    type II hypersensitivity
    cell damage caused by the binding of antibody and the activation of complement, usually against red blood cells
    type III hypersensitivity
    damage to tissues caused by the deposition of antibody-antigen (immune) complexes followed by the activation of complement
    variable region domain
    part of a lymphocyte antigen receptor that varies considerably between different receptor types
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