1.1 Pathogens

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  • Created by: maddie
  • Created on: 27-11-12 18:00
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  • 1.1 Pathogens
    • Microoragnism - unicellular organism too small to be seen by naked eye. Many live inside our bodiescausing no harm and soem benefit us. But some causes disease - pathogens
    • Disease - description of certain symptons either physical or mental, or both whish suggests a malfunction on the body or mind which has mental, physical or social aspects.
    • For a microorganism to be classed a pathogen it must...
      • gain entry to host
      • colonise and damage hosts tissues resulting in infection
        • disease occurs when infections leads to recognisable symptons
      • resist hosts defences
    • pathogens normally enter body by penetrating organisms interface(surface or boundary linking 2 systems) i.e. skin
      • skin effective barrie, invasion normally occurs when skin is broken. Someinterfaces of body - eveolved to allow exchange between 2 enviroments so thin, moist, large SA and many blood vessels.
        • feautres allow easy access to pathogens. Interfaces are common pooints of entry including...
          • gas-exchange system, e.g. brochitis and TB
          • Digestive system - food and water carry pathogens into stomach and inestine i.e. cholera
    • transmission - pathogen trasfered from one individual to another
    • defences to help prevent entry of pathogens...
      • enzymes to break down pahtogens
      • stomach acid to kill microorganisms
      • mucus layer covering exchagne surface - thick sticky barrier diffcutl to penetrate
    • pathogens causes disease in 2 mains ways...
      • damaging host tissues - sometimes the sheer number of pathogens causes damage. Viruses inhibit sythesis of DNA, RNA and proteins. Many pathogens break down membranes
      • producing toxins - most bacterial pathogens produce toxins
    • Some diseses have single cuases but other have several. Pathogens, lifestyle and genetic factors can cause disease.
    • how quickly pathogen causes damage, realted to how quickly it divides. Slower it divides, longer it takes to damage


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