BY4.7 Nerve Impulses

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Nerve Impulses

  • electrical charge associated with an impulse is very small: 50mv
  • impulses can eb recorded and measured
  • impuses are picked up from the nerves through a pair of microelectrodes and are fed into a cathode ray oscilloscope
  • measures the magnitude and speed of transmission of an impulse
  • can analyse patterns of impulses generated in different parts of the nervous system

Transmission of nerve impulses:

  • neurones transmit electrical impulses along cell surface membrane surrounding the axon
  • inside of the membrane had a more negative elctrical charge comapred to the outside

resting potential: the potential difference between the inside and outside of the membrane when a nerve impulse is not being conducted

- usually a minus value

Action potential:

  • the membrane is at resting potential of -70mv
  • voltage gated sodium and potassium channels are closed, the sodium potassium pump is open
  • potassium flows in and sodium flows out by active transport, the potential difference is negative inside the membrane
  • stimulus is appplied at the threshold (-50mv) is reached and action potential occurs
  • voltage gated sodium channels open quicker than the voltage gated potassium ones so sodium rushes in along an electrochemical gradient and concentration gradient
  • inside potential difference becomes more…


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