Movement of Substances

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  • Created by: Lotto65
  • Created on: 21-12-15 14:02
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  • Movement of Substances in the Body
    • Diffusion
      • In fluids
        • Liquids
        • Gases
        • Because they move randomly due to their energy
      • Movement of particles from high to low concentration (net movement)
        • Depends on concentration each side of membrane (difference in concentration between two areas)
          • Concentration gradient
          • Larger difference in concentration, greater the rate of diffusion
      • Spreading out of particles in a gas or in a solution
      • With or without a cell membrane
      • Examples
        • Oxygen from the lungs into the blood stream and into cells
        • Carbon dioxide from cells into blood and lungs
        • Carbon dioxide into actively photosynthesising plant cells
        • Simple sugars and amino acids from gut into cell membranes
    • Osmosis
      • ONLY with water molecules
        • Move randomly
      • Movement of water across partially permeable membrane
      • From high(dilute) to low(concentrated) solutions (net movement)
      • Types of solution
        • Isotonic
          • Equal concentration of water and solutes on either side of the membrane so no water moves by osmosis
        • Hypertonic
          • More concentrated (solutes) and little water content
          • You go hyper if you have had lots of sugar
          • Plasmolysis
            • Plants
            • Water leaves cells so vacuole and cytoplasm shrink.  Cell membrane pulls away from cell wall
        • Hypotonic
          • High water content( dilute) and low concentration of solutes
        • Usually refers to solution outside cell
    • Active Transport
      • Obtain substances in short supply
        • Against concentration gradient
        • Across partially permeable membrane
      • Low to high concentration (net movement)
        • Because it is against the concentration gradient
      • Examples
        • Glucose reabsorbed into kidney tubules
        • Absorption of mineral ions from dilute solutions in the soil


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