BIOLOGY 220 LECTURE #21 - Animal defenses 3 - Immune System - 11-17-07

BIOLOGY 220 LECTURE #21 - Animal defenses 3 - Immune System - 11-17-07

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BIOLOGY 220 – LECTURE #21 – ANIMAL DEFENSES 3: IMMUNE SYSTEM INTERACTIONS UNIT – 2 IMMUNE SYSTEM – HUMAN BODY! IMMUNE SYSTEM – 3 2 Divisions of the Immune System: o Nonspecific immunity: General barriers and defenses not specific to the pathogen A general keep out layer that is intended for all pathogens o Specific Immunity: Where we can identify the pathogen and destroy pathogen Long-term “memory” storage system – we can remember pathogens and particles like the identified particles NONSPECIFIC IMMUNITY - 4 Skin The skin is an outer layer of dead cells that completely covers the body These skin cells contain a protein called keratin Makes skin tough and structure Has a low pH on surface to inhibit the growth of certain bacteria (about 5.5) Normal skin bacteria exist on our skin at this low pH and out-compete any foreign bacteria Lysozymes in sweat and tears can digest bacterial cell walls and kills bacteria by osmotic lysis. o Lysozymes don’t last very long in the open environment We constantly are regenerating skin cells
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NONSPECIFIC IMMUNITY - 5 Skin doesn’t cover everything Mucus membranes – o Specialized linings on internal surfaces of the body o They secrete this mucus – traps unwanted particles o The digestive/reproductive tracts are used to destroy foreign elements Stomach acid, antibacterial saliva, push foreign entities out of the body as waste Coughing and sneezing remove pathogens from the body in place of manually digesting these particles NONSPECIFIC IMMUNITY – 6 Leukocytes – White blood cells – involved in non-specific response o 3 Types of white blood cells that do this: 1.) Macrophage – Amoeboid in structure – found in capillaries In the event of an infection, these diffuse out of the capillaries into the cell layers out into the extrastitial fluid surrounding tissues – they ingest pathogens through phagocytosis. Phagocytosis – surrounds a bacterium with membrane, pulls it into the body, it becomes a vesicle with bacterium in it – this phagosome fuses with a lysosome (which is full of digestive enzymes) – the lysosome digests the bacterium and uses the leftovers for respiration or other structures. Phagocytosis is the cellular process of engulfing solid particles by the cell membrane to form an internal phagosome, or "food vacuole." NONSPECIFIC IMMUNITY – 7 Leukocytes – White blood cells – involved in non-specific response o 3 Types of white blood cells that do this: 2.) Neutrophil – First responders to infection Come from capillaries as well Work just like macrophages – they ingest particles that are foreign o The difference between macrophages and neutrophils is: Structural (not as amoeboid) Additional chemicals in cell body to help digest pathogens Phagocytosis is the same mode of action to destroy foreign entities.
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NONSPECIFIC IMMUNITY – 8 Leukocytes
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BIOLOGY 220 LECTURE #21 - Animal defenses 3 - Immune System - 11-17-07

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