The Action Potential
Brief description and instructions (DRAFT):
The action potential is carried along the membrane and is driven by a wave of opening and closing ion channels. The initial phase of the action potential or depolarization is when the voltage at the membrane voltage goes from the resting potential of -70 mV to +30 mV and is driven by the opening of voltage dependent sodium ion channels allowing sodium to flow more freely into the neuron. This phase is immediately followed by the repolarization phase where the sodium channels close and voltage dependent potassium channels open allowing the potassium to flow out making the voltage inside the neuron to become even more negative than during the resting potential.
Using the illustration:
The membrane is drawn in orange with outside the neuron above the membrane. The voltage dependent sodium channels are green and the potassium channels are blue. As the action potential moves down the membrane it will change the color of the membrane to match its voltage with green being positive and red being negative. Press the Start button to initiate the animation. This button always restarts the animation from the beginning. The action potential will move from right to left. There is an electrode in the membrane. It registers the voltage at that point and this voltage is plotted on a graph below the electrode. The Play/Pause allows you to stop and start the animation again from the same point. During pauses there are Step Forward (+) and Step Backward (-) buttons to step the illustration along.
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