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36 Cards in this Set
- Front
- Back
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What is the first line of the body's immune defense?
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Skin and mucous membranes constitute the first line of defense. Their role is to prevent pathogens from entering the body. Protective membranes line all body cavities and organs exposed to the exterior.
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What kind of barrier are surface membranes? What additional defenses do they offer?
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Surface membranes provide mechanical barriers to pathogens. Some have structural modifications and produce secretions that enhance their defensive effects: The skin's acidity, lysozyme, mucus, keratin, and ciliated cells are examples.
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What is the second line of the body's immune defense?
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The innate cellular and chemical defenses provide the body's second line of defense.
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How to phagocytes contribute to body defense?
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Phagocytes (macrophages, neutrophils, and the like) engulf and destroy pathogens that breach epithelial barriers. This process is facilitated when antibodies or complement to which the phagocyte's receptors can bind attach to the pathogen's surface. Cell killing is enhanced by the respiratory burst.
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What are natural killer cells?
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Natural killer cells are large granular lymphocytes that act nonspecifically to kill virus-infected and malignant cells.
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Describe the purpose and process of the inflammatory response
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The inflammatory response prevents the spread of harmful agent, disposes of pathogens and dead tissue cells, and promotes healing. Exudate is formed; protective leukocytes enter the area; the area is walled off by fibrin; and tissue repair occurs.
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What are the signs of inflammation?
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The cardinal signs of inflammation are swelling, redness, heat, and pain. These result from vasodilation and increased permeability of blood vessels induced by inflamatory chemicals. If the inflamed area is a joint, movement may be impaired.
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What are interferons?
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Interferons are a group of related proteins synthesized by virus-infected cells and certain immune cells that prevent viruses from multiplying in other body cells.
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What processes are incurred by complement?
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When complement (a group of plasma proteins) is fixed on a foreign cell's membrane, lysis of the target cell occurs. Complement also enhances phagocytosis and the inflammatory and adaptive immune responses.
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What is the function of C-reactive protein?
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C-reactive protein indicates the level of infection or inflammation in the body. It also activates completement, facilitates phagocytosis, and targets cells for disposal.
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What is the purpose of fever, in terms of immune response?
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Fever enhances the body's fight against pathogens by increasing metabolism, which speeds up defensive actions and repair processes, and by prompting the liver and spleen to sequester iron and zinc needed for bacterial multiplication.
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Describe the third line of the body's immune defense
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The adaptive immune system recognizes something as foreign and acts to immobilize, neutralize, or remove it. The adaptive immune response is antigen-specific, systemic, and has memory. It provides the body's third line of defense.
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What are antigens?
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Antigens are substances capable of generating an immune repsonse
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What is the functional difference between complete and incomplete antigens?
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Complete antigens have both immunogenicity and reactivity. Incomplete antigens or haptens must combine with a body protein before becoming immunogenic.
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What are antigenic determinants?
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Antigenic determinants are the portions of antigen molecules that are recognized as foreign. Most antigens have many such sites.
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What are MHCs? What are the differences between class 1 and class 2 MHCs?
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Major histocompatibility complex (MHC) proteins are membrane-bound glycoproteins that mark our cells as "self" Class 1 MHC proteins are found on all body cells (except RBCs); the class II variety is found on surfaces of cells that function in the adaptive immune response.
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How are lymphocytes, T cells, and B cells educated?
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Lymphocytes arise from the hemocytoblasts of the bone marrow and are educated to develop immunocompetence and self-tolerance. T cells are educated in the thymus and confer cell-mediated immunity. B cells are educated in the bone marrow and provide humoral immunity. Immunocompetence is signaled by the appearance of antigen-specific receptors on the surface of the lymphocyte. Immunocompetent lymphocytes seed the lymphoid organs, where the antigen challenge occurs, and circulate between the blood, lymph, and lymphoid organs.
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How is antigen receptor diversity accomplished within B and T lymphocytes?
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In both B and T lymphocytes, antigen receptor diversity is generated by shuffling gene fragments.
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What are APCs? How do they interact with T cells?
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Antigen-presenting cells (APCs) include dendritic cells, macrophages, and B lymphocytes. They internalize antigens and present antigenic determinants on their surfaces for recognition by T cells.
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What is the primary adaptive response of B cells?
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Clonal selection and differentiation of B cells occur when antigens bind to their receptors, causing them to proliferate. Most of the clone members become plasma cells, which secrete antibodies. This is the primary adaptive immune response.
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How do memory B cells function?
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Other clone members become memory B cells, capable of mounting a rapid attack against the same antigen in subsequent encounters (secondary immune response). The memory cells provide humoral immunological memory.
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What are the differences between active and passive humoral immunity?
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Active humoral immunity is acquired during an infection or via vaccination and provides immunological memory. Passive immunity is conferred when a donor's antibodies are injected into the bloodstream, or when the mother's antibodies cross the placenta. Its protection is short-lived, immunological memory is not established.
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Describe the antibody monomer
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The antibody monomer consists of four polypeptide chains, two heavy and two light, connected by disulfide bonds. Each chain has both a constant and a variable region. Constant regions determine antibody function and class. Variable regions enable the antibody to recognize its appropriate antigen.
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What are the classes of antibodies?
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Five classes of antibodies exist: IgM, IgA, IgD, IgC, and IgE. They differ structurally and functionally.
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What are the functions of antibodies?
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Antibody functions include complement fixation and antigen neutralization, precipitation, and agglutination.
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What are monoclonal antibodies?
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Monoclonal antibodies are pure preparations of a single antibody type useful in diagnostic tests and in treatment for some typeso f cancer. They are prepared by fusing B cells with tumor cells to produce hybridomas
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How are Immunocompetent helper and cytotoxic T cells activated?
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Immunocompetent helper (Th) and cytotoxic (Tc) T cells are activated by binding to an antigen-containing MHC protein displayed on the surface of an APC. A costimulatory signal is also essential. Clonal selection occurs and the clone members differentiate into the appropriate effector T cells that mount the primary immune response. Some clone members become memory T cells.
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What are the funcitons of helper T cells?
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Helper T cells are required for full activation of most B and T cells, activate macrophages, and release essential cytokines. Cytotoxic T cells directly attack and kill infected cells and cancer cells. Regulartory (Treg) T cells help to maintain tolerance in the periphery. Ty8 cells, found in the intestinal mucosae, recognize damaged cells and pathogens in a number of novel ways
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How is the immune response enhanced?
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The immune response is enhanced by cytokines such as interleukin 1 released by macrophages, and interleukin 2, gamma interferon, and others released by activated T cells.
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What immune issues are experienced during grafts or foreign organ transplants?
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Grafts or foreign organ transplants are rejected by cell-mediated responses unless the patient is immuno-suppressed. Infections are major complications in such patients.
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What are the two common forms of immune disease? Why are they often fatal?
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Immunodeficiency diseases include severe combined immunodeficiency (SCID) syndromes and acquired immune deficiency syndrome (AIDS). Overwhelming infections are fatal because the immune system is unable to combat them.
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What is an autoimmune disease? What are examples?
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Autoimmune disease occurs when the body regards its own tissues as foreign and mounts an immune attack against them. Examples include rheumatoid arthritis and multiple sclerosis.
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What are the formal names for allergies?
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Hypersensitivity is an abnormally intense reaction to an otherwise harmless antigen. Immediate hypersensitivities (allergies) are mounted by IgE antibodies. Subacute hypersensitivities, involving both antibodies and complement, include antibody-mediated cytotoxic and immune-complex hypersensitivities. Cell-mediated hypersensitivity is called delayed hypersensitivity.
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When does the immune response develop?
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Development of the immune response occurs around the time of birth. The ability of the immune system to recognize foreign substances is genetically determined.
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How does the nervous system affect immune response?
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The nervous system plays an important roles in regulating immune responses, possibly through common mediators. Depression impairs immune function.
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How does aging affect the immune system?
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With aging, the immune system becomes less responsive. The elderly more often suffer from immune deficiency, autoimmune diseases, and cancer.
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