resting potential

    Cards (4)

    • intro
      • neurones transmit electrical impulses, they travel along the neurone cell surface membrane
      • impulse=momentary reversal in electrical potential difference across the neurone membrane
      • electrical potential difference=voltage/difference in charge
    • resting potential overview
      • -70mV
      • inside of axon has a negative electrical potential compared to outside
      • difference in charge is due to different number of ions on each side of neurone cell surface membrane
      • difference in charge across membrane=polarised
      • inside of axon has electrical potential 70mV lower than outside
    • maintaining resting potential
      1)active transport of sodium and potassium ions
      • carrier proteins(sodium-potassium pumps)are present in cell surface membrane of neurones
      • they use ATP to actively transport NA+ out of the axon and K+ into axon
      • pumped at an unequal rate: for every 3 NA+ pumped out, 2K+ are pumped in
      • this creates a concentration gradient across the membrane
    • maintaining resting potential
      2)difference in membrane permeability to sodium and potassium ions
      • concentration gradient created by pump-both NA+ and K+ will diffuse back across membrane
      • the cell membrane of axons have sodium and potassium channels that allow movement via facillitated diffusion
      • the neurone membrane is less permeable to NA+, so K+ can diffuse out at a faster rate than NA+ can diffuse back in
      =more positive ions on outside of neurone than inside
      =resting membrane potential is -70mV