Action potential (2)
Action potential 2
The slight depolarisation of the membrane to the point of the threshold causes the voltage dependent sodium channel to open rapidly. This is the initiation of the action potential.
The sodium ions rush inside the cell. This results in a depolarisation of the membrane potential towards +10mV, as there are relatively more positive ions inside the cell than there are outside the cell.
If the resting membrane potential is -70mV and the threshold is -55mV, a membrane potential of -60mV will:
Extra info: A membrane potential of -60mV is a depolarisation of the membrane that is not strong enough to create an action potential. However, the small depolarisation makes it easier to produce an action potential, because the potential is almost at the level of the threshold.
Action potentials are restricted to areas of excitable membranes that contain voltage-dependent channels.
Extra info: An action potential cannot be generated in a membrane without voltage dependent channels.