Hi, it's Paul, Andersen and in this video
I'm going to go over the basics of the neuron. The neuron is the basic unit in the nervous system. in a simple animal like
A nematode worm, they only have 302 neurons,
But what they allow them to do is to take information in from their surroundings and respond to that
Information. if you look at how those 302 neurons are connected it's very complex. Now humans are quite a bit bigger
And we have a hundred billion neurons in our body.
Most of those are centered in the central nervous system in the brain and the spinal Cord,
But the basic unit of our nervous system is the same: it's the neuron. If we look at the neuron
Anatomy and remove all the other neurons that the center is going to be what's called the cell body.
This is a typical cell. It's metabolizing. Cell. It's taking an energy
It's using that energy and so it's going to have a nucleus. It's going to have Golgi apparatus
Mitochondria, it's a typical cell but there are extensions of those cell bodies called the dendrites. Those dendrites are connected to other neurons
and they're taking information in in the form of neurotransmitters. In fact this whole side of the neuron is receiving information
We then have the axon the axon is where we're transmitting
Information it begins at the Axon hillock and is going to move to the terminals now remember the terminals
There's a synapse that connects us to other neurons, but the signal is going to move in this direction
We're taking in information from the dendrites the cell body, and then we can send information to the next neuron now
How do we do that is through an action potential and I have a video that
I'll put a link to where I go into the specifics of how that occurs
But certain axons in our body are really really long and for that information to travel quickly. We will wrap them in Myelin sheaths
It's a schwann Cell that's wrapped around it the way
It works is we put the voltage-gated channels in between that and it acts to insulate that nerve
It allows the information to travel more readily down that axon.
And, we generally say if you have an axon that's wrapped in Myelin sheath. We call that a nerve fiber inside our body now
We're taking in information as well
So there's going to be another neuron that's connected to both the cell body and the dendrites of that cell
But there's going to be a gap between these two and we call that a synapse
It's a connection between neurons. Again
I Have another video on the synapse if you want to dig into the specifics especially of how chemical synapses work neurons are classified in two
Ways first way is due to their structural classification, so if we take the cell body of a typical neuron
like this multipolar neuron
The way you can figure out what what type of a neuron is is?
Find the cell body and figure out how many poles are coming off of that cell body?
So if we count them, we have a number of different dendrites that are coming off of this neuron
And then we have at one axon that's coming off, and so we call that a multipolar neuron
This is the most common neuron that we have in our body if we look at the next one
We find the cell body again. How many poles do we have coming off of it?
We've got the axon coming out and the dendrite coming in and so we call this a bipolar neuron Bipolar Neurons are very rare
They transmit information from the receptors in our eye
receptors in our nose
If we look at the next one, here's the cell body you can see there's only one pole coming off of that
It's actually a fused axon and dendrite and we call that a unipolar neuron. Now in vertebrates
It's sometimes referred to as the pseudo uni-polar neuron these are going to be most of the sensory neurons in our body
They're taking information in and transmitting that back into the central nervous system
And then if we look on the next one if we look at that
You can see there's no axon on it as at all so we call that an Axonic neuron
These are found in the brain, and they're not super understood now there are a lot of other structural classifications
But these are the general ones that you're going to find in a typical anatomy class?
Now neurons can also be classified according to their functional classification those that take in information
stimulus coming in from our environment
And then the response that we have so if we kind of move that to the central nervous system
We're looking at a cross-section of the spine so we're taking information in from receptors
So these could be in the skin for example touch receptors heat receptors pain receptors
And so we have to transmit that information to the central nervous system. So those neurons that bring information in are
Sometimes refer to as sensory neurons or afferent neurons you can see this is a unipolar neuron
And it's transmitting that information into the central nervous system, and then we have information going back out
We're sending information out to effectors in our body: could be muscles, could be glands. And, we're going to call those motor neurons
They're moving away from the center
sometimes we refer to those as
afferent neurons as well now there should be connections between those neurons those aren't all the neurons we have in our body and so we
Also have these connections in the middle and those are going to be called inter neurons
And so that's the neuron
How did you do can you remember the different parts of the neuron do you remember that these are the dendrites the cell body?
Do you remember what type of a neuron this is if not go back and rewind it?
But those are neurons those are the basics, and I hope that was helpful