Anatomy & Physiology

Anatomy & Physiology Study Guide • Physical barriers include skin, mucous membranes, hair, epithelia, and various secretions of the integumentary and digestive systems. • The two types of phagocytic cells are microphages and macrophages (cells of the monocyte– macrophage system). Microphages are neutrophils and eosinophils in circulating blood. • Phagocytes leave the bloodstream by emigration, or diapedesis (migration between adjacent endothelial cells), and exhibit chemotaxis (sensitivity and orientation to chemical stimuli). • Immunological surveillance involves constant monitoring of normal tissues by NK cells that are sensitive to abnormal antigens on the surfaces of otherwise normal cells. NK cells kill cancer cells that have tumor-specific antigens on their surfaces. • Interferons—small proteins released by cells infected with viruses—trigger the production of antiviral proteins, which interfere with viral replication inside the cell. Interferons are cytokines—chemical messengers released by tissue cells to coordinate local activities. • The complement system is made up of at least 11 complement proteins that interact with each other. Their interaction is used to target and destroy plasma membranes, stimulate inflammation, attract phagocytes, or enhance phagocytosis. The complement system can be activated by either the classical pathway or the alternative pathway. • Inflammation is a localized tissue response to injury. • A fever (body temperature greater than 37.2°C [99°F]) can inhibit pathogens and accelerate metabolic processes. Pyrogens can reset the body’s thermostat and raise the temperature. Specific defenses (immunity) respond to individual threats and are either cell-mediated or antibody- mediated: • Antibody-mediated (humoral immunity) is provided by B cells, and cell-mediated (cellular) immunity is provided by T cells. • Specific resistance or immunity involves innate immunity (genetically determined and present at birth) or acquired immunity. The two types of acquired immunity are active immunity (which appears after exposure to an antigen) and passive immunity (produced by the transfer of antibodies from another source). • The four properties of immunity are specificity, versatility, memory, and tolerance. The memory cells are used by the body to help attach against repeat antigens, and tolerance is the bodies ability to ignore some antigens (like normal body cells). • The immune response is triggered by the presence of an antigen and includes cell-mediated and antibody-mediated defenses. T cells play a role in the initiation, maintenance, and control of the immune response: • Antigen presentation occurs when an antigen–glycoprotein combination appears in a plasma membrane (typically, that of a macrophage). T cells sensitive to this antigen are activated if they contact the membrane of the antigen-presenting cell. • All body cells have membrane glycoproteins. The genes controlling their synthesis make up a chromosomal region called the major histocompatibility complex (MHC). The membrane

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