B4

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  • Created by: A.Delle21
  • Created on: 06-01-17 17:37
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  • B4
    • Homeostasis
      • Maintaining a constant internal environment
        • Maintain core body temperature at 37 degrees C.
          • Negative feedback ensures that in control systems that changes are reversed and returned to the set level.
            • Controls body temperature, blood oxygen levels and salt levels
          • Feet and hands feel cold first because body works to maintain constant core temperature
        • Receptors > Processing Centre > Effectors
          • Receptors detect change
          • Processing centre receives information and coordinates a response
          • Effectors produce the response
      • Strenuous exercise and living in hot/cold environment effects body temp and water content
    • Urine
      • Temporarily stored in the bladder
      • Made up of urea, some water and some salts
      • Concentration changes depending on external temperature, exercise levels and intakes of fluids and salts
    • Thermoregulatory centre is in the brain
    • Glucose
      • Body cells get their constant supply of energy from glucose
      • Pancreas creates insulin  which causes glucose to move from the blood into the cells
        • When the blood glucose is too high more insulin is released
        • Diabetics can't control their blood glucose levels
          • When the blood glucose is too high more insulin is released
    • Diffusion
      • Takes place in the lungs: oxygen diffuses across the alveolar walls into the blood
        • When particles move from a region of high concentration to a region of low concentration
          • Diffusion
            • Takes place in the lungs: oxygen diffuses across the alveolar walls into the blood
              • When particles move from a region of high concentration to a region of low concentration
              • In a plant leaf CO2 moves from the air spaces between the mesophyll cells to the chloroplast
              • Osmosis is a special type of diffusion. It involves water
              • Equilibrium
                • When the  concentrationis the same on both sides
        • In a plant leaf CO2 moves from the air spaces between the mesophyll cells to the chloroplast
        • Osmosis is a special type of diffusion. It involves water
        • Equilibrium
          • When the  concentrationis the same on both sides
      • Enzymes
        • Enzymes speed up chemical reactions that keep cells alive and make them do their job
        • If the temperature gets too high the enzymes are denatures and stop working
        • A specific molecule binds to the enzyme in the active site and a reaction occurs
      • Active transport
        • Dissolved molecules move across cell membrane from lower concentrationto higher concentration
          • Particles move against concentrationgradienj which requires input of energy from cell
            • Takes place in humans during digestion of food in small intestine
      • Hypothalamus
        • Processing centre in brain that controls body temperature
        • Nerve impulses sent by it to skin which increases/decreases heat loss from body's surface
          • Vasodialation and Vasoconstriction
            • Blood vessels supplying blood to the skin swell/dialate
            • Controlled by signals along nerves from the hypothalamus

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