Action Potential

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Do curso por The University of Chicago

Compreendendo o Cérebro: Neurobiologia da Vida Cotidiana

671 classificações

The University of Chicago

Compreendendo o Cérebro: Neurobiologia da Vida Cotidiana

671 classificações

Learn how the nervous system produces behavior, how we use our brain every day, and how neuroscience can explain the common problems afflicting people today. We will study functional human neuroanatomy and neuronal communication, and then use this information to understand how we perceive the outside world, move our bodies voluntarily, stay alive, and play well with others.

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Neural Communication + Embodied Emotion

Neurons are the cells of the nervous system responsible for communicating, relaying, and integrating information. Neurons "talk" to other neurons through a special type of language that involves electrical signaling within individual neurons, and the use of chemical compounds known as neurotransmitters to communicate between neurons. In this module, you will learn more about how a neuron functions at rest, how information is relayed within a neuron, and how neurons relay information to other neurons or target tissues. In the second half of this module, you will be learning about how the body and emotions work together to produce our everyday emotional experiences. We will look at the enteric nervous system and learn how to discern whether the sympathetic or parasympathetic system is impacting our current emotional state.

Electrical Language7:36

Electricity Review4:25

Action Potential5:13

Conheça os instrutores

Peggy Mason
Professor
Neurobiology

[MUSIC]

So what we talked about in the last segment was how neurons sit at, at

a resting membrane potential of about negative 65 millivolts.

And through mechanisms that we're going to come to.

That resting membrane potential is just sort of the

it's the potential around which the neuron oscillates.

So, at, at one point it might get an input that.

If this is 0, that brings it closer to

0 or takes it farther away from 0, et cetera.

And these small little potential differences, which are on the

order of less than one millivolt up to, say, five millivolts.

These small, little potential differences, can travel, along the neuron.

If this is, if these are the dendrites and, and here's an axon.

They might travel, but they're going to peter out pretty quickly.

So, it's not a a useful it's not going to

work to simply rely on these small potential changes.

Now if we have to go long distances.

Now, one of the things that is so different about a neuron than

any other cell type in the body is that we are, that these neurons.

We [LAUGH] meet a neuron.

Neurons are very long.

Okay.

So think about a heart cell.

A heart cell is so big, it's contained in

the heart, it ain't going anywhere, besides the heart.

A pancreatic cell is sitting in the pancreas, it's in the pancreas.

It's pretty small.

A lung cell, et cetera.

Now, let's think about the longest neuron that we posses.

The longest neuron that we possess is a cell that has a cell body right here.

And it sends one process all the way down to the toe, and it

sends another process all the way up to the medulla.

So, depending on how tall this person is.

In me, that's a, one and a half meters, say, so five feet or something like that.

But in a very tall person, or even in

a very short person, that's still a lot of feet.

That's feet long.

So, a small potential like one millivolt or five millivolts is not going to travel.

If that's what we had to rely on, just moving from here

to here, the message, any message that started here would end there.

It just wouldn't get there.

It wouldn't get to where it needs to go.

It needs to go here.

And so, in order to, to communicate within neurons,

because neurons are so long, we use something called the Action Potential.

And the Action Potential, in contrast to being this, this kind of small thing, is.

It goes really far up and comes back down, so it's

about 100 millivolts in, in height.

So from the resting memory potential to the top of the

Action Potential, which happens at around plus say, 20 millivolts or so.

It's, we're talking about roughly 100 millivolts of, of difference.

And that can get communicated all the way up.

That's not going to get lost.

And what carries that Action Potential, is that.

Remember that we, we, we looked at potassium being very

high in a cell and much lower outside a cell.

Well, the reverse is true for sodium.

And so, the sodium comes flooding in, and because it's positively charged,

that's what takes the, the cell up to this very high memory potential.

Now the the ability for, for a neuron to communicate from

here to here using an Action Potential is, it can do that.

But that'll be a slow process unless we add

one more thing, and that is a, an insulator,

essentially a very nice insulator called myelin.

[MUSIC]

[MUSIC]

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