A.P

• Resting potential of neurone

  
  

  .3Na+ out, 2K+ in

  .Via sodium-potassium pump

  .K+ diffuse out via potassium ion channel

  
• Neurone resting potential

  -70mV
• A.P (de/repolarisation)

  Depolarisation:

  • If stimulus is great enough to reach threshold potential
  • At -50mV
  • All Na+ channels open & Na+ floods the neurone
  • Pd increases a bunch to +40mV (depolarisation)

  Repolarisation:

  • At +40mV
  • Voltage gated Na+ channels close
  • Voltage gated K+ channels open
  • K+ leave neurone
  • Pd drops to -70mV
  • K+ slow to close
  • So pd drops below -70mV (hyperpolarisation)
  • Goes back to -70mV - RP
  • Refractory period -
  • Na+ & K+ channels recovering, preventing backward stimulation