Inside; outside an action potential involves na+ moving the cell and k+ moving the cell.

An action potential involves na+ moving Inside the cell and k+ moving outside the cell.

The concentration of natrium is higher outside the cells. When action potential triggered, the ion canals will be opened an Natrium/sodium could go inside the cells. This will cause the potential become more positive rapidly, called depolarization. After a while kalium/potassium ion will be go out of the cell and cause the membrane potential become more negative again, called repolarization.

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