Lecture_32_DulaiS09_Immunity3

Lecture_32_DulaiS09_Immunity3 - 1 Principles of physiology...

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Unformatted text preview: 1 Principles of physiology (in two multicellular taxa) IMMUNITY IMMUNITY 2 Immunity is the ability of a multicellular organism to defend itself against invasion of pathogens (e.g., viruses, bacteria, fungi) Immunity has been studied in metazoans (animals) and some land plants ( flowering plants ) but is almost unknown in other multicellular groups, such as fungi and algae Immunity in land plants and immunity in animals rely on very distinct processes : they evolved independently of one another This lecture focuses on the immune system in animals , and more specifically vertebrates 3 Hundreds of species of microbes (mainly bacteria) live on the skin or in the internal tubes (e.g., gut). ost are neutral or even beneficial as long as they remain out of the internal environment of the body Many bacteria that are very abundant in our body ( Escherichia coli in the colon) or on our body ( Staphylococcus epidermis on skin); can cause severe infections once they cross the surface barrier. Your body contains 10x as many bacterial cells as human cells possibly 10% of your body weight possibly 10% of your body weight comes from microbes comes from microbes . Various places microbes reside 4-Our immune system needs to be able to distinguish which cells are part of our -own body own body and -foreign organisms foreign organisms (bacteria, parasitic worms, viruses, etc.); -our immune system must not attack our own body- Self and non-self recognition takes place at the molecular level : olecules (proteins in the vast majority of cases) of the immune system (usually called receptors ) recognize other molecules found in foreign organisms ( antigens )-So an antigen is any molecule that the body recognizes as non-self A key concept in immunity: Self versus non-self recognition 5 Three Lines of Defense Barriers at body surfaces Innate immunity (Passive) Adaptive immunity (Active) 6 The first line of defense against pathogens: surface barriers surface barriers A pathogen causes infection when it enters the internal environment of an organism, which means that a pathogen must cross the skin or the epithelium of internal tubes (e.g., gut) in order to enter the internal environment 7 Innate and Adaptive Immunity 8 Chemical Weapons in Immunity 9 Complement System Complement System Complement is made up of plasma proteins that take part in both both specific and nonspecific immune response Activation of one triggers cascade of reactions that activate others ultimately contribute to cell cell lysis lysis of an invading microbe 10 omplement can form attack complexes on bacterial cell membranes antibody activated complement bacterial pathogen lipid bilayer of pathogen Activation Cascade Reactions Formation of Attack Complexes Lysis of Target 11 Inflammation & Fever 12 Inflammation Redness Swelling Heat Pain 13...
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Lecture_32_DulaiS09_Immunity3 - 1 Principles of physiology...

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