Chapter 9
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Transcript of Chapter 9
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Chapter 9Innate Immunity: Nonspecific
Defenses of the Host
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Nonspecific Defenses of the Host
• Susceptibility: Lack of resistance to a disease.• Immunity: Ability to ward off disease.• Innate immunity: Defenses against any
pathogen.• Adaptive immunity: Immunity, resistance to a
specific pathogen.
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Host Defenses
Figure 16.1
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Physical Factors
• Skin• Epidermis consists of tightly packed cells with
– Keratin, a protective protein
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Physical Factors• Mucous membranes
• Ciliary escalator:
Microbes trapped in mucus
are transported away from
the lungs.
• Lacrimal apparatus:
Washes eye.
• Saliva: Washes microbes off.
• Urine: Flows out.
• Vaginal secretions: Flow out.Figure 16.4a
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Chemical Factors• Fungistatic fatty acid in sebum.• Low pH (3-5) of skin.• Lysozyme in perspiration, tears, saliva, and tissue
fluids.• Low pH (1.2-3.0) of gastric juice.• Transferrins in blood find iron.• NO inhibits ATP production.
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Normal Microbiota
• Microbial antagonism/competitive exclusion: Normal microbiota compete with pathogens.
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Formed Elements in Blood
Table 16.1 (1 of 2)
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Table 16.1 (2 of 2)
Formed Elements in Blood
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Neutrophils 60-70%Basophils 0.5-1%
Eosinophils 2-4%
Monocytes 3-8%
Lymphocytes 20-25%
Differential White Cell Count
• Percentage of each type of white cell in a sample of 100 white blood cells.
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White Blood Cells
• Neutrophils: Phagocytic• Basophils: Produce histamine• Eosinophils: Toxic to parasites and some phagocytosis• Dendritic cells: Initiate adaptive immune response• Monocytes: Phagocytic as mature macrophages
– Fixed macrophages in lungs, liver, and bronchi– Wandering macrophages roam tissues.
• Lymphocytes: Involved in specific immunity.
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Phagocytosis• Phago: from Greek,
meaning eat• Cyte: from Greek,
meaning cell• Ingestion of microbes
or particles by a cell, performed by phagocytes.
Figure 16.6
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Phagocytosis
Figure 16.7
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Inhibit adherence: M protein, capsules
Streptococcus pyogenes, S. pneumoniae
Kill phagocytes: Leukocidins Staphylococcus aureus
Lyse phagocytes: Membrane attack complex
Listeriamonocytogenes
Escape phagosome Shigella
Prevent phagosome-lysosome fusion
HIV
Survive in phagolysosome Coxiella burnetti
Microbial Evasion of Phagocytosis
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Inflammation• Redness
• Pain
• Heat
• Swelling (edema)
• Acute-phase proteins activated (complement, cytokine, and
kinins)
• Vasodilation (histamine, kinins, prostaglandins, and leukotrienes)
• Margination and emigration of WBCs
• Tissue repair