the difference between an action potential and a resting potential
The potential that is recorded when a living cell is impaled with a microelectrode is called the resting potential, and varies from cell to cell. Here it is shown to be -60 mV, but can range between -80 mV and -40 mV, depending on the particular type of nerve cell. In the absence of any stimulation, the resting potential is generally constant. It is also possible to record and study the action potential. Figure 1.3 illustrates an example in which a neuron has already been impaled with one microelectrode (the recording electrode), which is connected to a voltmeter. The electrode records a resting potential of -60 mV.
Action potentials are generated by special types of voltage-gated ion channels embedded in a cell's plasma membrane. These channels are shut when the membrane potential is near the resting potential of the cell, but they rapidly begin to open if the membrane potential increases to a precisely defined threshold value.