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Unformatted text preview: Pathology-Immunity and Immune Disorders Biology of the Immune System • Immune system= collection of mechanisms that protects against disease and their products by identifying and killing pathogens, and tumour cells and protection against microbial toxins • Immunology= science that examines the structure and function of the immune system • Pathogens: viruses, bacteria, mycobacteria, parasites and fungi • For the immune system to properly function it has to distinguish pathogens from self healthy cells • Innate immune system: natural, born with it, not specific, does not require previous exposure to Ag/stimulant; characters: exposure leads to immediate maximal response, it is non specific, it does not require a previous exposure to an offending agent (antigen) and found in nearly all forms of life • Adaptive immune system: acquired, more specific, requires previous exposure to a stimulant; characters: pathogen and antigen specific response, lag time between exposure and maximal response, cell mediated and humoral (Ab) components, cell mediated and humoral components (of inflammatory response), exposure leads to immunological memory, found only in jawed vertebrates • Antigen= antibody generator= substances that bind to specific immune receptors and elicit immune response General characteristics of innate and acquired immunity • 1. Recognition: the ability to distinguish between normal self, altered (damaged) self and non-self (foreign material) • 2. Specificity: the ability to inactivate, destroy and remove the “offending” material, without damaging normal tissues in the vicinity of the reaction; reaction must be target specific • 3. Regulation: the immune system is able to control the type, intensity and duration of the reaction and has the ability to prevent immune reaction (suppression) • 4. Amplification: the effector (attack) phase of the immune reaction is mediated through multiple pathways which act synergistically for optimal effect; each pathway has built-in amplification systems; all these systems have different triggering points and each may be triggered independently, but eventually involve the other systems • 5. Memory: the identity of the foreign material (immunogen) which led to the first (primary) immune response is remembered so that the next episode involving the same immunogen will result in an accelerated reaction (secondary immune response), which by-pass several initial steps that the primary immune response has to go through; confers long term immunity against infection Innate Immunity • Takes place when a microorganism is able to break through the normal epithelial barriers of the skin, GI and respiratory tract; phagocytes ingest microbes and secrete cytokines which stimulate the inflammatory response; cells have various receptors (PRRs) that are able to recognize components that are preserved among broad groups of micro-organisms; GPCRs are the receptors for chemokines • Phagocytes have phagocyte receptors that recognize coated organisms or components of the microbe itself or complement that activate it;...
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This note was uploaded on 02/08/2012 for the course PATHOLOGY 3245 taught by Professor X during the Spring '11 term at UWO.
- Spring '11