Change in Membrane Potential - Video Tutorials & Practice Problems
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concept
Change in Membrane Potential
Video duration:
3m
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Video transcript
So this video is going to be about change in membrane potential. Now, you guys all know about resting membrane potential, right, But neurons can't stay resting forever. Eventually, that membrane potential has to change. And when that happens, we can get 2 types of signals. The first is called a graded potential. And the second type, you've already heard of this I bet, is called an action potential. Now we're gonna have quite a few detailed videos talking about each of those moving forward, but first, we're gonna cover some important terminology that's gonna help you understand when we're talking about neural communication. So our first term that we have here is polarized, as in the neuron is polarized. And what this means is that the inside of the membrane is negative. I'm gonna put a little negative sign right there and you can see this is not just any old negative. This is negative 70 millivolts, which we know is resting potential. Right? So a neuron that is polarized is a neuron that is at rest. So I'm actually gonna draw a little graph for us really quick just to help us visualize this. So I'm gonna put negative 70 down here. We'll put a little dotted line and I'll put something positive up here. I'll do positive 20. Alright. So if we are polarized we are just hanging out right here at negative 70 and we're resting. Now sometimes our neuron will depolarize or will have a depolarization. What that means is that the inside of our membrane is becoming more positive. So we're going to give him a positive sign right there and this would look literally just like this. So we are spiking and we're getting more and more positive in our membrane. Now this is sometimes called a temporary decrease in membrane potential. So I always remember that we depolarize to decrease decrease membrane potential. Okay? Now once we're up here our neuron doesn't want to stay up here forever. Neurons like to be negative where they can rest. Right? So eventually we're gonna have a repolarization and that is when the inside of our membrane becomes more negative. So he's getting a negative sign right there and that would look just like that. So here, well, how I like to remember this is that we repolarize to return to rest. So we're going back down down down toward a negative 70 millivolts. Now, sometimes neurons when they're trying to repolarize they get a little too excited and they kind of overshoot that and so they they kinda dip below negative 70 and that is called a hyperpolarization. So a hyperpolarization is when the inside of our membrane becomes more negative than resting potential. You can think of this as, like, hyper kind of means too much of something. Right? And in this case, it's too much negativity. So we're gonna give him double negative signs. He is too negative and this is sometimes called a temporary increase in membrane potential. Okay? So that's kind of us swooping a little bit too too low there. Now I would highly encourage you to take your time with these terms. Make sure that you understand them because moving forward understanding neural communication will be much easier if you can hear one of these words and immediately know what is happening to that membrane potential. So study these, take your time with them, and when you're ready, I'll see you in our next video. Bye bye.
2
example
Change in Membrane Potential Example 1
Video duration:
1m
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Video transcript
Okay, so in this example we have this nice graph here and along the x axis we have our membrane potential plotted, and along the y axis we have time. And you can see this change in membrane potential has been plotted in the graph and so what we're going to do is fill out the vocabulary term that corresponds to each of those changes in the membrane potential. So let's dive right in and we're going to start down here sitting pretty at negative 70 millivolts which we know is resting potential and a neuron at rest is a neuron that is polarized. Right? So we're going to start with our neuron polarized. Now here along this blue line we can see we're getting more and more positive and the only term here that describes our membrane getting more positive is depolarization. Right? So this is the depolarization that we're looking at here and then, whoop, here we go. We're getting back down toward those negatives, which must be our repolarization. Right? We repolarize to return to rest. We're trying to get back down here to negative 70 and then whoops right there looks like we overshot that and we got 2 negative. So that is our hyperpolarization. Remember, hyper is like too much of something, so we actually got 2 negative and that's what that looks like dipping down below negative 70. So there you have it. We start off polarized at resting potential. Here we have the depolarization phase, our neurons getting more and more positive. Here is our repolarization phase, we're getting back down into those negatives, and we overshot that a little bit and ended up hyperpolarizing very briefly. So there you go, and I will see you guys in our next video. Bye bye.
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Problem
Problem
A neuron's membrane potential goes from -90 mV to -10 mV. Which of the following terms describes this change?
A
Hyperpolarization.
B
Polarization.
C
Depolarization.
D
Repolarization.
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