1. The membrane stars in its resting state, polarised, with the inside of the cell being -60mV compared to the outside
  2. Sodium ion channels open when triggered by a change in the external environment (such as pressure). As a result some sodium ions diffuse into the cell
  3. The membrane depolarises, it becomes less negative with respect to the outside and reaches the threshold value of -50mV
  4. Voltage-gated sodium ion channels open and many sodium ions flood in. As more sodium ions enter the cell becomes positively charged compared with the outside
  5. The potential difference across the membrane reaches +40mV. The inside of the cell is more positive than the outside
  6. The sodium ion channels close and potassium ion channels open
  7. Potassium ions diffuse out of the cell down a concentration difference, bringing the potential difference back to negative inside compared with the outside. This is called repolarisation.
  8. The potential difference overshoots slightly, making the cell hyperpolarised.
  9. The original potential difference is restored so that the cell returns to its resting state.
  10. C’est fini!