Can someone explain the steps of voltage-gated ion channels in action potential?

Answer 1

Ok, some kind of stimulus generates a local potential in a neuron. Something that may initiate a local potential is a neurotransmitter from a different neuron synapsing to this neuron. Or lets say for a "touch" neuron, receptors can sense mechanical pressure, and that causes some initial gate to open allowing some sodium ions to enter the cell.

So given that we are starting with a certain resting membrane potential (created ONLY by the concentration gradient and charge gradient caused by POTASSIUM LEAK CHANNELS), some kind of stimulus, as explained above, will allow an influx of Na+ ions, which will make the membrane potential more POSITIVE. If the membrane potential reaches a certain value called the threshold potential (meaning if the stimulus is enough to open Na+ voltage gated channels), a full action potential will be fired all the way along the axon.

How does this happen? The change in the membrane potential from the original resting potential, to the threshold potential causes some confortmational change in VOLTAGE GATED Na+ channels. At threshold potential, these Na+ voltage gated channels open, and Na+ RUSHES into the cell. When this happens, this voltage change stimulates the next set of Na+ channels to open along the axon, and that stimulates the next set, etc. all the way along the axon.

But as this happens, the voltage changes created by sodium rushing in also stimulates the opening of K+ channels, and K+ wants to rush OUT of the cell, since the inside of the cell has become more positive due to the entry of positively charged sodium ions, and also the concentration of K+ is greater inside than it is out.

So the influx of sodium ions drives the membrane potential positive, and K+ eflux drives the membrane potential more neagtively, back toward the original resting membrane potential, and this fluctuation in membrane potential is sent along the axon. This is just the same thing as sending a message along a wire in the form of a current.

Answer 2

lol your right sci and this eric guy goes and puts im a science teacher i have 10 years experience on all his answers and half of them are wrong what a donk!!