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Fall 2010: Topic 3 Lecture Notes this is the information is topic 3 called "ecology of the human body and health:infectious diseases" including infectious organisms, the biology of infectious diseases, the epidemiology of infectious diseases, Internal Eco

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Health Studies
HLTH 101
Glenn Ward

Tuesday September 28 2010 Topic three The Ecology of The Human Body and Health Infectious Diseases 1 Infectious Organisms Infectious organisms can be classified in a number of ways first by size then according to their taxonomic classificationsi SUBCELLULAR ORGANISMSNot technically organism but complex microscopic agents that usually reside within living cells Two types viruses and prionsa VirusesExists as RNA or DNA molecules encased in a protein coat1500 viruses have been identified only a small number affect human healthHave simple existence outside host cellObligate intracellular parasites must enter host cell to reproduceAll cells are susceptible for viral infection even bacteria bacteriophagesViral reproduction can damage host cell offspring invades new cells and replicates damaging new cell etcViruses travel throughout body therefore low association between entry route and tissue affected Diseases caused include common cold HIVAIDS influenza HPV herpes measles b PRIONSProteinacaous infectious particlesLack DNA and RNA mainly protein like moleculesExist in all brainsSusceptible to alterations in shapeIf altered altered prions reproduce and spread to nearby cellsLeads to death or neural cells with prions Altered prions can be transmitted through foodsurgical instruments as infectious agentsDiseased caused include transmissible spongiform encephalopathy CJD CreutzfeldtJakob diseasevCJD form of CJD associated with bovine spongiform encephalopathy BSEii UNICELLULAR ORGANISMSExist as single cellsMore complex than viruses and prions still simpleHighly specialized for respective environmentsTwo types associated with infectious disease bacteria and protozoaa Bacteriaunicellular prokaryotic organismsstructurally highly adapted for survival 1 most enclosed in a capsulecapsule allows resistance to phagocytosiscapsule plays role in virulence of bacteria 2 Bacterial cell walls contain peptidoglycan except archaebacteriaProvides rigidity and resistance to lysisDetermines gram positive and gram negative status of bacterium for determining antibiotic treatment 3 Some bacteria have cytoplasmic organelles called plasmidsPlasmids have selfreplicatingnon chromosomal DNA which can be transferred to other bacteriaBacteria sometimes transfer virulence and genetic resistance to other bacterial cells 4 Some bacteria produce sporesSpores have condensed version of bacterial cell with DNA within a specialized coat to resist heat humidity harmful chemicals etc To ensure survival and generation when not inhabiting a living hostBacteria are characterized by rapid rate of reproduction binary fission When associated with illness can produce illness within hours of infecting hostMost are nonpathogenic and essential for human lifeWhen harmful actions are due to 1 Toxins produced by bacterial reproductionReleased in human body after infectionsReleased in food or water consumed by humans 2 Tissue invasion of bacteria leading to inflammationtissue deathEffects of bacteria usually associated with site of entryDiseases include cholera syphilis gonorrhoea Chlamydia botulism E Coli Lyme disease gastric ulcers H Pylori and food poisoning b ProtozoaUnicellular eukaryotic organisms Ubiquitous more than 20 000 species only a few are harmful to humansMore complication life cycleMore than one host
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