In this video, we're going to begin our lesson on the neuron, more specifically focusing on the structure of the neuron. 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. A neuron has three basic structural parts. The first is the dendrites. The second is the cell body or the soma. The third is the axon. The dendrites are extensions that lead into the cell body and are responsible for receiving incoming electrical signals. The cell body or the soma contains the nucleus of the cell and most of the organelles of the cell as well. Lastly, the axon is a long thin portion of the neuron that conducts outgoing electrical signals. I want to emphasize that axons can be pretty long, up to several feet in some cases, which is really long for a single cell.
Notice the short memory tool below to help you remember that dendrites receive the incoming signals, whereas the axon transmits or conducts the outgoing signals. The signals enter via the dendrites, emphasizing the 'en' in enter and dendrites. The axon takes the signal away, relating 'a' in axon to 'a' in away. Let's take a look at our example image below where we can label the three parts of the neuron and indicate the direction of an electrical impulse traveling through the cell.
This image here shows the neuron, with extensions leading into the cell body, known as dendrites. The dendrites receive the incoming signal. You can think the signal enters via the dendrites. Here, you can see the cell body or the soma, which contains the nucleus of the cell and most of the organelles. Notice the long portion of the neuron below here is the axon. The axon is this long thin portion of the neuron that conducts outgoing electrical signals. If we wanted to trace the path of an electrical signal, we could use a red color. The electrical signal is received by the dendrites, starting at the dendrites. Then the electrical signal travels through the cell body and moves into the axon, going in this direction. The axon conducts the outgoing signal. This is 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 transmitted to the next neighboring neuron or a muscle cell, for example.
This concludes our brief lesson on the neuron, and we will be able to get some practice moving forward. I'll see you all in our next video.