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Nonspecific body defenses: A. surface protection (1st line of defense) 1. Skin Prevents entry Acidic pH prevents bacterial growth 2. Mucous membranes Ex: Mucous, gastric juice, cilia, nasal hair, lining of vagina, tears, saliva B. Internal defense 1. antimicrobial proteins: a. interferons – released by virus-infected cells and prevent viral replication in neighboring cells b. transferrins – iron-binding proteins reduce growth of some bacteria 2. Phagocytes and natural killer cells Cellular defense a. phagocytes Neutrophils & macrophages (enlarged monocytes) Engulfs a foreign particle/microbe Cytoplasm pulls it into vacuole. Binds with lysosome b. Natural killer cells Lymphocytes Releases chemicals onto target’s cell membrane to destroy it. Doesn’t destroy microbes 3. Fever temperature of hypothalamus reset by pyrogens (chemicals secreted by WBCs exposed to foreign substance) + increases speed of repair, inhibit microbe growth, helps interferons - denature enzymes of the body if too high 4. Inflammatory response kill microbe/prevent spread/tissue repair Vasodilation Increased permeability of capillaries 4 cardinal signs of inflammation: Redness, heat, swelling, pain 4. Inflammatory response kill microbe/prevent spread/tissue repair Vasodilation red, heat Brings nutrients in blood to injured site Increased permeability of capillaries swell 4 cardinal signs of inflammation: Redness, heat, swelling, pain Steps of inflammatory response: Chemical alarm causes: Involved blood vessels to dilate (vasodilation)and capillaries to become leaky (increased permeability). Vasodilation increases nutrients to area (causes redness and heat. Heat increases metabolism of tissue cells) Permeability of capillaries allows plasma to leak (causing clotting proteins to “wall off” damaged area and edema – swelling – which activates pain receptors) Activation of pain receptors Possibly to cause immobilization and therefore rest Attract phagocytes and WBCs to area For clean-up: disposes of cell debris and pathogens