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Unformatted text preview: Anatomy & Physiology II Notes 3/20/07 Immune System Cont. Nonspecific defenses o Internal defenses Phagocytes WBCs involved in phagocytosis, engulf and destroy pathogens o Neutrophils 70% of WBCs, involved in phagocytosis, polymorphonuclear lymphocytes (PMNs) o Eosinohils kills parasitic worms, inactivate inflammatory agents o Basophils release histamine and other inflammatory mediators o Lymphocytes involved in specific immunity, 20-25% of WBCs o Monocytes develop into macrophages Steps of phagocytosis o Phagocyte engulfs the particle and forms a vesicle o Vesicle is fused with a lysosome o Microbe in fused vesicle is killed and digested by lysosomal enzymes, leaving a residual body o Residual material is removed by exocytosis Fever NK (natural killer) cells attack virus-infected or cancerous cells (cells that look molecularly altered), destroys cell or directs it to destroy itself (causes cell to lyse...
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