<s>[INST] However, Fry himself notes that when the cell is depleted so that its membrane potential drops below 0.6 V , the channel opens allowing the sodium ions to flood in. The sodium rushes into the cell rapidly depolarizing it, and changing the membrane potential from - 0.8 V to - 0.4 V , completely disrupting the semi - permeable nature of the cell membrane . A rapid series of action potentials, or electrical impulses, are generated at a frequency dependent on the intensity of the stimulus , as a result of this rapid change in the membrane potential .[/INST]