Final answer:
The change in membrane potential during an action potential is from -70 mV to +30 mV, representing the nervous tissue's electrical communication signal.
Step-by-step explanation:
The explosive increase in sodium permeability during the generation of an action potential results in a rapid change in the membrane potential of that region of the cell from –70 mV to +30 mV. This drastic change is the key mechanism by which nerve cells communicate electrical signals.
When the neuron is at rest, it maintains a resting membrane potential of about -70 mV. Upon excitation, voltage-gated sodium channels open, and the influx of Na+ ions causes the membrane potential to increase rapidly. This event shifts the membrane potential from -70 mV to roughly +30 mV, a 100 mV change, during the peak of the action potential. Subsequently, these sodium channels close, and potassium channels open, allowing K+ ions to exit the cell, which begins the process of repolarization, eventually returning the membrane potential to the resting state.