Nervous Tissue: The Neuron

In this video, we're going to begin our lesson on the neuron more specifically focusing in on the structure of the neuron. And so recall from our previous lesson videos that the primary cell of the nervous tissue is the neuron and it is responsible for generating and conducting electrical impulses. Now, a neuron is going to have three basic structural parts. The first is going to be the dendrites. The second is the cell body or the SOMA and the third is going to be the axon. Now the dendrites are going to be extensions that lead into the cell body and they are going to be responsible for receiving incoming electrical signals. Now, the cell body or the SOMA is going to contain the nucleus of the cell and it is also going to have most of the organelles of the cell as well. Now, last but not least here, the axon is going to be a long thin portion of the neuron that is going to conduct outgoing electrical signals. Now, I want to put some emphasis on the fact that the axons can be pretty long, several feet long in some cases. And so that's really long for a single cell. And so notice down below what we have is a short little memory tool to help you remember that the dendrites receive the incoming signals, whereas the axon is going to transmit or conduct the outgoing signals. And so the memory tool is really just that signals are going to enter via the dendrites. And so notice the emphasis on the en and enter and the en and dendrites and then the axon is going to take the signal away. And so you can think a an axon is for a and away. And so let's take a look at our example image down below where we can label the three parts of the neuron and indicate the direction of an electrical impulse traveling through the cell. And so what you'll notice is that this image right here is the neuron. And notice that towards the top up here, these extensions that are leading into the cell body as you see all around right here, these are going to be the dendrites and again, the dendrites are going to receive the incoming signal. And so you can think the signal enters via the dendrites. Now, of course, right here, you can see that this is going to be the cell body or the SOMA if you will, and the cell body or the SOMA is going to contain the nucleus of the cell and most of the organelles. And then notice that this long portion of the neuron down below right here is going to be the axon. And again, the axon is going to be this long thin portion of the neuron that's going to be conducting outgoing electrical signals. And so if we wanted to trace the path of an electrical signal, we could uh use a red color. And so again, the electrical signal is going to uh be received by the dendrites. And so the electrical signal would start in the dendrites. So we could put like AAA red circle to say it's going to start here. And then the electrical signal is going to travel, be conducted through the cell body and then it's going to move into the axon and move in this direction. And again, the axon is going to be conducting the outgoing signal. And so this is going to be the direction of the electrical impulse traveling through the cell starting in the dendrites, moving through the cell body, then going through the axon as an outgoing signal to be um transmitted to the next neighboring neuron perhaps or a muscle cell, for example. And so this year concludes our brief lesson on the neuron and we'll be able to get some practice moving forward. So I'll see you all in our next video.

Which of the following is the most likely path of an electrical signal travelling through a neuron and arriving at a muscle?

• A. Neuroglia → dendrites → a cell body → axon → muscle.
• B. Dendrites → cell body → axon → muscle.
• C. Dendrites → axon → cell body → muscle.
• D. Axon → cell body → dendrites → muscle.