Response and Regelation

Just something to help learn response and regulation

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  • Created by: Owain
  • Created on: 03-01-13 18:37
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  • Response and Regulation
    • Receptor cells
      • They are a group a special cells which are sense organs
      • They respond to stimuli (changes in the enviroment)
      • Receptor cells send this information to the central nervouse system
      • The information is sent as electrical signals called Impulses
      • The impulses travel along nerve cells called neurons
    • Plant responses
      • Plant roots grow towards gravity - this is called POSITIVE GRAVITROPISM
      • Plant shoots (the parts above the ground) grow towards light - this is called POSITIVE PHOTOTROPISM
      • Plants responses are controlled by chemicals called HORMONES
    • Homeostasis - These are all the ways in which the body keeps conditions inside the body constant
      • Concentration of water
      • PH
      • Blood glucose (sugar) levels
        • If blood sugar levels get too high (e.g. after a meal containing carbohydrates)
        • The pancreas releases the hormone insulin into the blood
        • Blood glucose levels must be kept within constant range
        • The blood carries the insulin to the liver
        • The liver changes glucose to insoluble glycogen which it stores
        • Blood glucose levels decrease
        • Type 1 diabetes
          • Doctors can diagnose diabetes by testing urine for glucose
          • This is because the pancreas does not produce enough insulin
          • We can test artificial samples of urine for glucose by
            • Putting the test-tube in a beaker and boiling it
            • Adding Benedict's solution to the sample in a test-tube
            • There could be a colour change
              • Benedict's changes from blue to orange = Glucose present
              • Benedict's solution stays blue=No glucose sample
          • This is a condition where blood glucose levels may rise fatally high
      • Temperature
        • Too hot
          • Blood vessels
            • Less heat los
            • Blood vessels become narrower
            • Less blood flows through
          • Sweating
            • Sweat released to surface through sweat pore
            • Sweat evapor
            • Sweat travels up through sweat duct
            • Sweat glands produce more sweat
            • Evaporation takes heat away from skin
          • Shivering
            • No shivering
          • Hairs
            • Less air trapped
            • Hair lies flat
            • Less insulation
            • Erector muscle relaxes
            • More heat lost
        • Too cold
          • Sweating
            • Sweat glands produce less sweat
          • Hairs
            • Layer of air trapped
            • Hair pulled upright
            • Air is an insulator
            • Erector muscles contracts
            • Less heat lost
          • Shivering
            • Shivering = contraction of muscles
            • More respiration
            • More energy needed
            • More heat released
          • Blood vessels
            • Less blood through
            • Blood vessels become narrower
            • Less heat lost
    • Negative feedback - It is a process which makes sure that any changes that are made are reversed to bring the condition back within normal range


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