ireland3e_immune_ch09_fall11

ireland3e_immune_ch09_fall11 - Chapter 9 Immunity and the...

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11/2/2011 1 Chapter 9 Immunity and the Lymphatic System Defenses Our immune system has three lines of defense innate immunity, or non-specific immunity first line of defense the cutaneous membrane (skin) and mucous membranes second line of defense antimicrobial proteins (interferon), fever, inflammation, and phagocytes specific immunity third line of defense includes the interactions of white blood cells, antibodies, and macrophages
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11/2/2011 2 Innate Defenses Skin Skin is the primary physical barrier Skin is the largest organ of the human body it encases the body, protecting it from desiccation (drying out) and preventing the entry of disease-causing microbes The skin maintains homeostasis regulates water content regulates temperature It produces vitamin D, necessary for bone growth and development
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11/2/2011 3 Skin The skin is composed of a superficial epidermis and a deeper dermis the epidermis is composed of stratified squamous epithelium the epithelium has no blood supply The top layer of the epidermis is composed of dead cells joined by strong cell- to-cell junctions which are filled with keratin this layer of dead keratinocytes provides the skin's nonspecific defense against invasive pathogens few pathogens are attracted to dead cells keratin repels waterborne pathogens along with water Mucous Membranes Mucous membranes provide nonspecific immunity they line any cavity open to the exterior mouth digestive tract respiratory tract urinary tract reproductive tract Mucus retards pathogens it is secreted by the epithelial cells of the membrane
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11/2/2011 4 Innate Chemical Barriers When the physical innate barriers (i.e., skin and mucous membranes) fail to stop a pathogen, chemical barriers aid in the first line of defense Chemical barriers include sebum forms a protective acidic film over the skin surface that is hostile to many bacteria perspiration, tears, and saliva contain an enzyme called lysozyme, which is a natural antibacterial chemical gastric juices extremely low pH of the acid produced by the stomach lining (approximately pH 2) creates an unfriendly environment for many pathogens bacteria help create a hostile environment for other microbes Antimicrobial Proteins The complement system a series of chemical reactions brings together a group of proteins that are usually floating freely in the plasma these proteins are stacked in a specific order to create a “complement” of proteins that function like an antibacterial missile when a bacterial invasion is encountered, the complement complex assembles, attaches to the bacterial walls, and impales the cell with the protein complex with the bacterial wall breached, osmotic pressure forces water into the bacterium, destroying its chemistry and killing it The complement system is effective against bacteria but not viruses
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11/2/2011 5 The Complement System
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This note was uploaded on 12/26/2011 for the course BSC 2023 taught by Professor Staff during the Fall '08 term at FIU.

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ireland3e_immune_ch09_fall11 - Chapter 9 Immunity and the...

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