Action Potentials, Part 2"},"lengthSeconds":"608","ownerProfileUrl":"http://www.youtube.com/user/susJun 17, 2021
Picking up immediately after repolarization, you will now see hyperpolarization. You can use a purple highlighter and go over that orange
part. It can be a circle and that is the purple number five. We call it hyperpolarization and the reason it happens is because the potassium channels closed slowly. allowing the cell to be momentarily more negative and at rest so now even though you are in a situation where how do you get back to square one and this is where that bomb is so important here? I'm going to use a black pen sodium-potassium remember it's three ATPase pumps from sodium to potassium that put sodium back to where it started, which is outside the cell, and put potassium back inside the cell, so it is important for it to come back to rest and then the pump maintains that resting membrane potential until the next
actionpotential is fired any kind of venom or disease that affects this sodium potassium ATPase pump or the venom of a snake will kill you if you don't reverse quickly because without the sodium and potassium ATPase pump you couldn't keep firing
potentialsbecause eventually you would lose the negativity that the cell has now we'll look at this action potential and just put a few more things in there for with a pink pen you could mark here that this is the threshold and at that point then with your green pen at that point all the sodium channels open and it seems like almost as fast you go up to the top and then at this point all the sodium channels close and then the potassium channels open so you start to see this pattern, if the sodium channels are open the cell loses.
It depolarizes. If the potassium channels are open, the cell repolarizes and even hyperpolarizes for a moment. Remember that I mentioned that the frequency of action
potentialsis how the intensity is coded. I'm going to write that again or here and let's look at this if one line represents an action potential tell me about the intensity of these two lines you can see quite easily right this is not very intense and this is intense I like to think about it like ringing the bell in my neighborhood we have a lot of little voices second grade i have a first grade toddler and they love to play together well they don't like to wait for a door to open properly so if you go to a door and ring the bell inside the house, you hear ding dong or whatever yours does.
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action potentials part 2 lengthseconds 608 ownerprofileurl http www youtube com user sus...
Well, what if the child really wants you to open the door? Does the inside of the house go ding dong? I'm about to yell at the kids and give them a little timbre etiquette lesson, so this is what's going on in my neighborhood, well that's what I mean by increasing the frequency of the action potential, the timbre, or the potential of action no. does not get stronger does nothing h Higher than plus 30 and yet the body is capable of interpreting the frequency of action potentials as a great intensity of either sensation, either with the force with the that someone has touched you or how much you want that muscle to contract and how hard you want it to contract.
So either sensory or motor increasing the frequency of action potentials is all it takes to encode the intensity ok now to show you you can only increase the frequency for sure it's like you can't have it anymore close than here, let's say true, I mean this has to end. I'm not saying this very well, look here if you have an action potential that goes up, it has to come back down before it can go back up. they go together so there's something called the absolute refractory period when no matter how intense you want the signal to be you can't fire two action potentials at the same time so there's a limit to that and then there's something called the relative refractory period where if the stimulus is strong enough it could trigger another action potential but you can only have the action potential so close, think about this with ringing, it might depend on what kind of ringing you have, but in my house, if the kid is ringing the doorbell pressing the button too many times instead of hearing a dingdong i start hearing a ding ding ding ding like this and it goes a little faster but it's not getting all the dingdong so it can just see so fast or kids push it, let's say the kid is pressing the doorbell 10 times 1 2 3 4 5 6 7 8 9 10 inside the house, you may only hear ding dong ding dong ding dong, you may that you only listen 3 times s so there is a limit to how quickly action potentials can come together ok there is one more thing I want you to put on this page and that is to get a general idea of where all of this is happening these they're dendrites here's an axon mound and then some ranvier nodes now use a different feather how about pink that would be perfect this is where the graded potentials occur that's where we colored pink they're on the dendrites and they might look like this a little light flashing like that so no up or down either, either a flash up or a flash down, but keep in mind they never quite got to the height of an action potential and then that kind of diffusion diffuses to the mound from the axon and would only use the hello there if the threshold reached ap is triggered but also back to normal and then on each of these you get propagation again ask it to happen again and that's the propagation which I could write, maybe you can write that side spread and instead of shooting, maybe it'll spawn you
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