Psych: Action Potential

• Key Terms


  • Action Potential
  • Electrical impulse
  • By depolarisation
  • Resting Membrane Potential
  • Electrical potential difference between neuron and cell membrane
  • Indicating readiness for polarisation
  • Neuron's Membrane
  • 0.00001mm thick, -70mV resting potential
  • Slightly negative charge inside (compared to outside)
  • Cell Membrane
  • Electrically polarised
  • Negative charge due to chloride and protein molecules
  • Positive out due to sodium and potassium ions
  • Electrostatic forces (electric gradient)
  • Opposites attract
  • Positive ions attract negative
  • Affected by concentration gradient
• Action potential

  • Selective permeable
  • Na+ in, K+ out (no charge or polar change)
  • Electrostatic force + conc. gradient
  • Sodium-potassium pump
  • Stop Na+ influx alter polarisation/charge
  • Na+ in faster than pump removes (+ charge rise; depolarisation)
  • Reach -55mV: impulse down axon
  • Return resting:
  • Conc. gradient push Na+ out
  • No electrostatic (same charge)
  • Lots K+ in (- charge)
  • S-P P restore balance
  • Chemical message stimulates either
  • Excitatory
  • Ion flow in
  • Depolarisation + AP
  • Hyperpolarisation inc charge + polarisation
  • Inhibitory
  • AP less likely
  • Inc threshold