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Anatomy Chapter 12.docx

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Biological Sciences
Connie Soros

Chapter 12 Body Defenses • External Defenses (first line of defense) - Skin (integument) 1. physical barrier a. keratinocytes form barrier, also influence immune cells 2. skin-associated lymphoid tissue (SALT) a. contain specialized immune cells 3. chemical barrier a. secretions of sweat and oil (sebaceous) glands are toxic to bacteria - Mucous membranes and associated structures (line cavities open to outside of body) 1. digestive tract a. salivary enzymes kill bacteria b. acid in stomach kills bacteria c. secretions contain antibodies d. normal intestinal bacteria outcompete pathogens (disease causing organisms) e. gut-associated lymphoid tissue (GALT) a.k.a. Peyer's patches contain immune cells f. appendix contains immune cells 2. genitourinary tract a. acidic urine b. acidic vaginal secretions c. sticky mucus in genitourinary tract traps pathogens & has antibodies (1) swept out as organ empties (2) engulfed by phagocytes 3. respiratory tract a. large particles filtered by hairs in nasal passages b. tonsils and adenoids contain immune cells c. sticky mucus traps pathogens in airways (1) cilia sweeps mucus upward (swallowed, or coughing, sneezing or expectorating removes it from body) (2) antibodies secreted in mucus d. alveolar (air sac) macrophages engulf pathogens • Defense Cells - WBCs 1. neutrophils: highly mobile phagocytes 2. eosinophils: secrete chemicals that kill parasitic worms, involved in allergic reactions 3. basophils: release histamine and heparin (inflammatory response) involved in allergic reactions 4. lymphocytes: can reproduce outside bone marrow (in lymphoid tissues like lymph nodes) a. B lymphocytes: secrete antibodies (1) probably mature in bone marrow b. T lymphocytes: destroy virus infected and cancer cells (1) mature in thymus 5. monocytes: become macrophages - large phagocytes in tissues - most in tissues, some circulate in blood 1. lymphocytes (and some others) found in lymphoid tissues a. store, produce or process lymphocytes b. lymph nodes, spleen, thymus, tonsils, adenoids, appendix, SALT, GALT c. located to catch invaders and decrease their spread • Nonspecific defenses (general defenses or innate immunity) - responses that defend against any invader or abnormal material - Inflammation (Inflammatory Response) 1. designed to bring phagocytes and plasma proteins to injured area a. destroy/inactivate invaders b. clean up debris c. prepare for healing d. characteristics include redness, heat, swelling and pain 2. resident macrophages begin phagocytosis 3. histamine released from mast cells (similar to basophils, present in connective tissues) causes... a. vasodilation  increased blood flow (redness, heat) b. increased capillary permeability  plasma proteins flow out,  edema (swelling, pain) 4. "walling off" of area due to fibrin forming interstitial fluid clots (inhibits spread of invader) 5. neutrophils and monocytes migrate to area a. margination - CAMs on capillary cells cause leukocytes to stick to capillary walls b. move to tissues by diapedesis c. leukocytes follow chemical trail to damaged tissue (chemotaxis) d. phagocytosis occurs to recognized substances (1) rough surfaces of damaged cells (2) opsonins - chemical placed on foreign cell by immune system, links it to phagocyte (antibodies, complement) e. phagocyte secretions (cytokines) enhance response (1) nitric oxide (toxic to bacteria) (2) lactoferrin (binds iron so bacteria can't use it to reproduce) (3) histamine (4) clotting triggers (5) enzymes that trigger kinin production (stimulate complement, reinforce histamine effects, activate pain receptors, act as chemotaxins) (6) endogenous
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