Intro | Inside Electrode at Rest | Outside Electrode at Rest | Inside Electrode with Action Potential | Outside Electrode with Action Potential
Part 1: Image-Mapped Tutorial
Part 2: Matching Self-Test
Part 3: Multiple-Choice Self-Test
When a neuron is stimulated sufficiently by another neuron or by a sensory event, an action potential occurs. There is a brief change in the polarity of the electrical charge across the cell membrane. Specifically, the membrane changes its permeability to the charged ions, and the charge across the cell membrane becomes less negative or more positive for just an instant. The action potential is visualized as a brief spike of +40 mV when measured by an oscilloscope. When an action potential occurs, the positively charged sodium ions flow rapidly into the neuron. The charge inside the neuron reverses polarity to become positive.