Because there are ions moving back and forth, there's a current that flows and there's a electrical potential that's generated.

由于离子的进进出出,就产生了电流流动,并且形成了电势差

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That potential difference is generated by the movement of ions, principally sodium and potassium across the membrane.

电势差是由离子运动造成的,特别是钠和钾的跨膜运动

耶鲁公开课 - 生物医学工程探索课程节选