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Chapter_32-_Immune_System - Chapter 32 BIO 1002 Chapter 32...

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Chapter 32 BIO 1002 4/1/2008 Chapter 32: Defense Against Disease: The Immune System Three lines of defense against microbial (viruses, bacteria, fungi, and protists) attack: - Nonspecific (reacts to all things the same way, a very general way to protect against infection) I. Nonspecific External Barriers : (skin and mucous membranes that are the lining for all internal organs, eyes, etc.) a. Skin : a physical barrier to microbial entry - Inhospitable (harsh) environment for growth; dry, dead cells at surface. Sweat/sebaceous glands secreting acids and natural antibiotics like lactic acid. - Prevent entry and growth of microbes b. Mucous membranes : of respiratory and digestive tracts are well defined. - Secretions have antibacterial enzymes - Example: Figure 32-2: the protective function of mucus c. Stomach : if microbes swallowed, acids and protein-digesting enzymes destroy them II. Nonspecific Internal Defense: a. Phagocytic cells : white blood cells (WBC) in extracellular fluid, amoeboid shape, destroy microbes by phagocytosis (engulf and directly destroy microbes) - Example from text book b. Natural killer cells : white blood cells that destroy body cells infected by viruses and cancerous cells by punching HOLES in them, shooting holes in them, much easier to kill the entire cells rather than rid only the infection c. Inflammatory response : caused by large-scale microbial invasion through a wound; histamine released by damaged cells (*Figure 32-4): 1) Tissue damage carries bacteria into the wound 2) Wounded cells release chemicals that stimulate mast cells 3) Mast cells release histamine 4) Histamine increases capillary blood flow and permeability 5) Phagocytes leaves capillaries and ingest bacteria and dead cells 1
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Chapter 32 BIO 1002 4/1/2008 - Histamine
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