The action potential moves along the neurone.
- When an action potential happens, some of the sodium ions that enter the neurone diffuse sideways.
- This causes sodium ion channels in the next region of the neurone to open and sodium ions diffuse into that part.
- This causes a wave of depolarisation to travel along the neurone.
- The wave moves away from the parts of the membrane in the refractory period because these parts can’t fire an action potential.
The refractory period produces discrete impulses
- During the refractory period, ion channels are recovering and can’t be opened.
- So the refractory period acts as a time delay between one action potential and the next. This makes sure that action potentials don’t overlap but pass along as discrete (separate) impulses.
- The refractory period also makes sure action potentials are unidirectional (they travel in one direction).
Action potentials have an All – or Nothing Nature
Once the threshold is reached, an action potential will always fire with the same change in voltage, no…