Causes of Disease

Biology AQA new AS level: pathogens, data and disease

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Microorganisms - are single celled organisms including bacteria, viruses and fungi. Some are beneficial and some are pathogens.

Disease - is a change in the body or mind with adverse effects on health. Has physical, mental and social aspects.

Infection - when a disease leads to symptoms.

  • For a microorganism to be a pathogen it must:
    • Gain entry.
    • Colonise tissues.
    • Resist defences.
    • Damage tissues.
  • They gain entry by:
    • Penetrating an interface with the environment e.g cut, gas exchange system (thin, moist) or digestive system (food carries them in).
  • They cause disease by damaging host tissue or producing toxins.
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Data and Disease.

Correlation - occurs when a change in 1 or 2 variables is reflected by a change in another variable, i.e. the realtionship between 2 variables.

Causal link - change in 1 variable results from or is caused by a change in another.

Looking Critically at Data

  • Right factor measured.
  • Correct questions asked and any unanswered.
  • How data was gathered, with reliable method and right apparatus.
  • If researcher had vested interets.
  • Repeated by others.
  • Sample size and age of data.
  • Any other factors to explain causal link.
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Lifestyle and Health.

Lifestyle - way of life including patterns of behaviour and personal choices affecting health risk.

Risk - a measure of probability damage to health will occur as a result of a given hazard. It has 2 elements: probability that the hazardous event will occur and consequences of that event.

  • Health risks need a timescale.
  • Statistics can be misleading.
  • Risk is often relative - risk measured by comparing likelihood of harm occurring in those exposed to a hazard compared to those who aren't.
  • Risk factors and cancer:
  • Carcinogenic factors risk contracting cancer e.g. smoking, diet, obesity, exercise and sunlight.
  • Risk factors and CHD:
  • Some factors beyond control e.g. genes and age.
  • Lifestyle factors e.g. smoking, high blood pressure, cholesterol, BMI higher than 25, salt and fatty acids in diet and lack of exercise.
  • Reduce risk by having less alcohol and more antioxidants.
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the info is really good, but the bottom gets cut off when you try to print them

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