Final answer:
All living cells maintain a potential difference or voltage across their plasma membrane, key for cellular activities and communication, with typical values being a negative resting potential around -70 to -90 mV.
Step-by-step explanation:
All living cells have a potential difference or voltage across their plasma membrane, and the actual value varies according to cell type. A typical potential difference ranges from 70 to 90 mV, reflecting the separation of charges. This difference creates an electric field which, despite the membrane's thin size of about 7 to 10 nm, turns out to be quite strong. In neurons at rest, the interior of the cell has a resting potential of about -90 mV when compared to the exterior which is taken to be at 0 V. This resting potential is critical for the function of nerve and muscle cells, with a significant amount of a cell's energy dedicated to establishing and maintaining it.
When a nerve cell is stimulated, there is an influx of sodium ions (Na+) through the membrane, which changes the electric potential, and this change initiates the nerve signal. The capability to create and manipulate these electric potentials is fundamental to cellular activities, particularly in the communication within and between cells.