My_Ch43_lecture(2009050122141024)

My_Ch43_lecture(2009050122141024) - Chapter 43: Immune...

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Chapter 43: Immune System Purpose—to understand how the human body defends itself against pathogens, and what happens when this system does not work normally What you MUST know in Ch 43: External defense Internal defense Antigen recognition by lymphocytes Clonal selection Humoral vs. Cell-mediated immunity Primary vs. Secondary immune response Active vs. Passive immunization Self vs. nonself Allergies Autoimmune disease HIV Here are some resources for the immune system: http://www.immunecentral.com/immune-system/iss1.cfm http://uhaweb.hartford.edu/BUGL/immune.htm http://biology.clc.uc.edu/Courses/bio105/immune.htm The function of the immune system is to defend the body against invading pathogens (disease-causing bacteria, viruses, other parasitic organisms). Your internal environment is an attractive habitat for these potential invaders. There are 3 lines of defense to protect us from pathogens: Nonspecific defense mechanisms —try to keep out everything, and do not target specific pathogens for removal or destruction. Includes: First line of defense : (external defense)
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o Skin and mucous membranes provide a physical and chemical barrier to pathogens Skin is a physical barrier, covered with protective acidic secretions (sweat glands) Lysozyme (destroys bacterial cell walls) and other antimicrobial proteins in saliva, tears, and mucous membrane secretions Cilia line respiratory passages and lungs to sweep particulate invaders out Gastric juice is acidic, kills most bacteria Symbiotic bacteria in digestive system and elsewhere out-compete pathogenic organisms (which is why over-treatment or mistreatment with antibiotics can have negative effects) Second line of defense: (= part of internal defense) o Still nonspecific, tries to remove all pathogens o Phagocytes are white blood cells (leukocytes, WBC) that remove pathogens by engulfing & then digesting them with lysosomal enzymes by phagocytosis Neutrophils engulf and destroy any and all bacteria (then self-destruct, so lifespan is a few days) Monocytes develop into large cells called macrophages which are longer-lived, and remove bacteria by phagocytosis Natural killer cells do not do phagocytosis, tumor cells , by attacking the infected or abnormal cell’s membrane and lysing (bursting o Complement is a group of about 25 anti- microbial proteins that work together to “complement” defense reactions by attracting phagocytes to foreign cells and promoting cell lysis
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o Interferons are proteins secreted by virus-infected cells, and prevent cell-to-cell spread of virus infection by inducing neighboring (uninfected) cells to inhibit viral reproduction. Interferons are not specific to a particular virus. o
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This note was uploaded on 09/29/2011 for the course BIO 020.152 taught by Professor Pearlman during the Fall '08 term at Johns Hopkins.

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My_Ch43_lecture(2009050122141024) - Chapter 43: Immune...

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