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Welcome to BioVid Episode 2.
My name is Leslie Samuel
and in this video I am going to give you
an introduction to neurons.
Inside this video, I’m first going to talk about the definition of a neuron,
then I’m gonna talk about about the four main parts of a neuron,
and, lastly, I’m gonna talk about the different types of neurons.
However, before we go into the definition of a neuron,
I want you to imagine a situation with me.
Let’s say you’re at home and you’re getting ready to cook a nice meal.
You turn on the stove but then you get a call from someone you haven't heard from in a long time.
You get on the phone with that person,
you start talking about life and it totally slips your mind that you had the stove on.
A little later, you walk into the kitchen and,
not thinking about it,
you take your hand and you rest it down on the hot burner.
Now, you can imagine with me that you will not be smiling like this lady in this picture.
As a matter of fact, you’ll probably look a little more like this lady.
But let’s think about what’s happening right now.
There’s intense stimulation sending signals to your spinal cord and to your brain.
There are signals sent back to the muscles in your arm to tell your muscles to contract
so that you can pull away from that intense stimulation and not feel the pain anymore.
There are signals being interpreted by your brain as intense pain.
So there are a lot of signals that are travelling throughout your nervous system.
Now that we have that situation in mind,
let’s talk about the definition of a neuron.
A neuron is a very specialized cell that forms the basis of the entire nervous system.
It is also referred to as a nerve cell.
These cells are specialized in that they send signals
throughout the whole body and they can do that really rapidly.
This animation gives you an idea of how these cells can send signals
from one to another in a very rapid way and, actually, it happens significantly faster
than what is depicted here.
Let’s talk about the four main parts of a neuron.
First we have the dendrites and
these are points where this cell receives input from other cells.
Then, we have the soma, or the cell body.
This is the part of the neuron that is the most like any other cell.
This is also the place where the neuron receives input and
also a place where a lot of processing is happening.
You can find the nucleus of the cell inside the cell body.
Then we have the axon
which is where the signal actually originates so that it can be sent
all the way down to the axon terminals.
And the axon terminals are the points where it connects with other neurons and
sends signals to other neurons by releasing chemicals called neurotransmitters.
And we’re gonna get into that in a later tutorial.
There are three main types of neurons.
First we have sensory neurons and
these are neurons that send signals to the central nervous system (CNS).
And if you remember from the last tutorial,
the CNS is made up of the brain and spinal cord.
Then, we have motor neurons that send signals away from the CNS and
to organs and muscles and tissues and glands and so on.
Lastly, we have interneurons, and
these are neurons that are contained fully within the CNS,
that is, within the brain, within the spinal cord, and this is where a lot of the processing happens.
To illustrate this, let’s image you are being touched by someone, or,
as in the first example, you touch a hot stove.
Signals are going to be sent to the CNS and
this happens via sensory neurons.
Then, let’s imagine you’re out on the field playing football and
you’re getting ready to kick the ball.
Well, the CNS is sending signals to the muscles in your legs
and it does that via motor neurons that tell the muscles in the leg to contract
in a certain way so you can kick the ball.
And of course there are interneurons in the brain and spinal cord
doing a lot of processing and also serving as a connection between sensory input and motor output.
To recap what we discussed in this video:
First, the definition of a neuron,
secondly, I spoke about the four main parts of the neuron,
and lastly, I spoke about the three types of neurons.