J._Defenses_blank

J._Defenses_blank - Principles of Biology II Defenses This...

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Principles of Biology II Defenses This lecture will cover Chapter 43. Read the chapter (or at least the chapter summary) quickly before coming to class. Do not let all the terminology discourage you; I will specify what to know during the lecture. You are responsible for the material under “External Defenses” on page 899. Your immune system Defenses Chapters 43 Leucocytes • White blood cells • All begin development in bone marrow – Most complete development in bone marrow – Exception: T-lymphocytes migrate to thymus and mature there • Kinds Neutrophils : phagocytic (especially bacteria) Monocytes : phagocytic • May leave blood and become macrophages in body tissues • Larger and can eat larger things Eosinophils : allergic reactions and killing parasites Basophils : release histamines during allergic reaction (as do mast cells in connective tissues) - Dilate blood vessels and constrict airways Lymphocytes (t and b cells ): immunity Natural killer cells
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Lymphoid tissues • Central/primary: where lymphocytes mature – Bone marrow and thymus – After maturation lymphocytes migrate to secondary tissues • Peripheral/secondary – Sites in body where lymphocytes may come into contact with foreign cells/substances – Lymph nodes, tonsils, digestive tract, spleen – Roles • Detect and destroy foreign cells/substances, damaged cells, cellular debris • Spleen: also removes damaged/old red blood cells Body Defenses • Against – Foreign invaders: pathogens • Viruses, bacteria, other parasites • Their chemical products (toxins) – Abnormal cells • Three “lines of defense” (figure 43.2) • Innate, inherited (nonspecific) • Do not depend on prior exposure to pathogens –Precise identity is not important • Generalized: combat whole classes of pathogens • First two lines of defense A. First line • Prevent entry into body • Add to “External Defenses” (page 899) – Coughing and sneezing
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– Vomiting and diarrhea – Acidity of vagina and urine B. Second line • Used if first line is penetrated (infection) • Respond to any pathogen without first determining its identity 1. Phagocytosis • Pathogens are engulfed by neutrophils and monocytes (macrophages) • Phagocytic cells can be found – In blood – Migrating in extracellular fluid – In peripheral lymphoid tissues 2. Natural killer cells • White blood cells • Detect virus-infected or abnormal (cancer) cells • Secrete proteins (that poke holes)
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J._Defenses_blank - Principles of Biology II Defenses This...

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