Lymphocytes white blood cells multiply rapidly when

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lymphocytes (white blood cells) multiply rapidly when in contact with an antigen (foreign substance) skin, mucous linings, nonspecific first line of defense mechanisms skin - oily, acidic (3-5 pH) barrier antimicrobial proteins (lysozyme - breaks down bacteria cell walls) - in saliva, tears, other secretions cilia - line lungs gastric juice - stomach, kills most microbes symbiotic bacteria - digestive tract/vagina, outcompete organisms nonspecific second line of defense phagocytes (neutrophils, monocytes/macrophages, natural killer white blood cells) - engulf antigens complement proteins - lyse antigen cell wall interferons - inhibit viral replicaiton, activate antiviral actions inflammatory response
histamine - secreted by basophils (white blood cells/leukocytes in connective tissue) vasodilation - increase blood supply, easier movement of wbc (redness, increased temperature) immune cells - lymphocytes (T-, B-cells), MHC (major histocompatibility complex markers) distinguish self T-cells - recognize foreign antigen MHC markers and clone themselves, cell-mediated response made in bone marrow, mature in thymus helper t-cells - activate B-lymphocytes and other t-cells, bind to microphages memory t-cells - recognize prior bacteria/virus encounters cytotoxic t-cells - recognize and kill infected cells B-cells - antibody-mediated response (humoral immunity) antibody/immunoglobulin (IgA/D/E/G/M) - proteins that inactivate antigens by binding to them memory b-cells - produce plasma cells after infection -> release specific antibodies helper t/b-cells - produce interleukins (communication channels) to eliminate subsequent invasion immunity antibiotics - chemicals from bacteria/fungi, harmful to other microorganisms vaccine - stimulates production of memory cells to protein coat on virus booster - reexposure to antigen due to decreased concentration of antibodies over time passive immunity - placenta/breast milk AIDS - destroys helper t-cells, prevents immune response Homestatic mechanisms thermoregulation ectotherms ("cold blooded") - temperature varies with environment (reptiles, amphibians) endotherms ("warm blooded", homeotherms) - generate own body heat (mammals, birds) cooling by evaporation (sweating, panting) warming by metabolism (muscle contraction, shivering) surface area - vasodilation/constriction regulates temperature negative feedback system - hormonal excess signals production to stop Hormonal control in homeostasis and reproduction - maintains homeostasis by antagonistic hormones hormone characteristics - transported in blood, may be steroids (lipid soluble)/peptides/modified amino acids neurosecretory cells - link hypothalamus with pituitary gland, secrete hormones into blood posterior pituitary - stores ADH (antidiuretic hormone) and oxytocin, targets specific body tissues anterior pituitary - releasing hormones stimulate release of tropic hormones (regulate other hormones) triggering hormone (steroid) diffuses through membrane/cytoplasm -> nucleus, binds to receptor protein -> DNA hormone (peptide) binds to receptor protein on plasma membrane (receptor-mediated endocytosis)

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