#action potentials

Your neuron, at its resting potential, has a charge of -70 mv. which is super tiny but whatever. And this means that there is a higher concentration of potassium (K) inside the cell than there is sodium (Na+). This is fabulous and altogether kind of boring. You have channels that let Na out and K in. (But not the other way around) You also have pumps that throw out 3Na for every 2K taken in. There are also leaky channels that are basically really shitty at doing their job and they let potassium come and go as it pleases.

I don't know why I need to know about channels and pumps and leaky thingies but whatever they're important.

So. SOMETHING HAPPENS. and your neuron gets super fucking excited. And it deppolarizes. This means that the membrane potential of this neuron gets closer to zero. It doesn't have to get much closer to zero than -60 mv and then it fires. which is thrilling as fuck.

because all the sodium channels open so Na floods the cell all FUCK YEAH BITCHES PARTY TIME!!!~~ Meanwhile potassium, because that's like the chemical of us computer-loving recluses, high tails it out of the neuron because they don't want any of these obnoxious sodium ions harshing their internet vibes.

And this continues until the membrane potential of the cell reaches like +40mv. So basically there is a freakin' rave happening in this cell and everything is really intense and -- BOOM. THE NEURON BECOMES REFRACTORY. THE BOUNCERS GET THEIR SHIT TOGETHER AND NO MORE SODIUM IS ALLOWED IN.

But the potassium doesn't get the message even though the cell is hyperpolarizing again. So you have a bunch of K ions fleeing just as the Na ions are getting bounced the hell out of dodge. And this causes the membrane potential to plummet below zero.

Then the potassium channels close and the sodium channels reset themselves. But by now the neuron is hyperpolarized and is below the resting potential of -70mv. This is the absolute refractory period. There will be no more cell boners until the extra potassium has diffused and the neuron is back at -70mv.