Lecture 12

Lecture 12 - The Immune System Lecture 12 Infectious attack...

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The Immune System – Lecture 12 Infectious attack Body is constantly under attack Must distinguish foreign from native molecules Must communicate/coordinate between elements of immune system Protect three main access routes to the body o Respiratory tract o Digestive tract o Skin lesions All passages are protected in multiple ways Epithelium All three passages have an epithelial tissue lining o Tightly packed cells; impenetrable barrier o Produce lysozymes to break bacterial cell walls o Secrete mucus to trap invading organisms Sweat glands on skin/stomach acid o Embedded within the epithelium are many important immune cells Innate and adaptive immunity Successful invasion past the epithelial defenses meets two other levels of defense: o Nonspecific (innate) immune system Acts very rapidly against infectious attack Detects broad classes of molecules o Specific (adaptive) immune system Slower to respond Detects specific patterns seen on classes of molecules Innate and adaptive immunity are highly interconnected Antigens Every cell can be identified by the molecules on its surface All immune system responses rely on recognizing foreign vs. native molecules An antigen is a molecule that provokes an immune response o Innate and adaptive A specific part or sequence of an antigen is an antigenic determinant or epitope o Each epitope can elicit a different response Figure 51.5 Immune detection Innate immunity detects broad classes of foreign antigens o Foreign = not “self-made” o Double stranded RNA, lipopolysaccharide, mannose-rich carbohydrates Adaptive immunity detects specific epitopes o Is “educated” to avoid self-made patterns o A specific sequence of amino acids o A specific shape of part of a surface protein
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Both use many signaling molecules to integrate/coordinate the attack Cytokines Primary signaling molecules in immunity o Protein/peptide based; are pleiotropic Can have different affects Produced in response to damage or infection Are alarm molecules-alert other cells o Induced resistance of noninfected cells
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Lecture 12 - The Immune System Lecture 12 Infectious attack...

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