Intro | Depolarization | Hyperpolarization | Action Potential | Threshold of Excitation
Part 1: Image-Mapped Tutorial
Part 2: Matching Self-Test
Part 3: Multiple-Choice Self-Test
In general, stimulation of an axon membrane acts to decrease the negativity of charge inside the membrane, by the opening of sodium channels. When the sodium channels are opened, sodium ions (which are at greater concentration outside the neuron at rest) flow into the neuron with the concentration gradient and electrostatic pressure. If, however, the stimulation exceeds 5 to 15 mV and reaches a depolarized state of -65 to -55 mV, or the Threshold of Excitation, an all-or-none response will occur. This response has consistent characteristics regardless of the intensity of the initiating stimulus, as long as threshold is reached.