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  • Created by: Jo Wells
  • Created on: 22-04-13 19:47
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  • Homeostasis
    • 'the maintenance of a CONSTANT INTERNAL ENVIRONMENT'
    • 6 things which need to be controlled
      • 4 need to be at just the right level
        • body temperature
          • enzymes in body work best at around 37 degrees C
          • if body gets too hot/cold enzymes won't work properly & some reactions could be disrupted
          • the thermoregulatory centre in the brain acts as a personal thermostat
            • contains receptors, which are sensitive to the temperature of the blood flowing through the brain
            • also receives impulses from the skin, giving info about skin temperatures
              • if getting too hot/cold, the body responds by trying to cool/warm you down/up
          • too hot
            • hairs lie flat
            • sweat is produced which evaporates from skin, removing heat
            • blood vessels supplying skin dilate so more flows close to the surface of the skin = easy for heat to be transferred from blood to environment
          • too cold
            • hairs stand up to trap an insulating layer of air
            • no sweat is produced
            • blood vessels supplying skin capillaries constrict to close off skin's blood supply
            • shiver - needs respiration, which releases some energy to warm the body
        • water content
        • ion content
          • (see kidneys)
            • water content
            • urea
        • blood sugar level
      • 2 are waste products
        • carbon dioxide
        • urea


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