Action Potentials

Ionic Movements

An action potential consists of a set of ionic movements. The ions move across the cell membrane when the correct channels are opened.

An actional potential consists of the following stages:

1. The membraine starts in its resting state - polarised with the inside of the cell being -60mV compared to the outside.

2. Sodium ion channels open and 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…