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Next Generation: HS.LS1.2 MS.LS1.3 MS.LS1.3 NGSS



This lesson will describe the function of the nervous system as well as the structure and function of a neuron and will include detail about the three types of neurons.

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Nervous System Intro: Neurons

Source: Video and Images Created by Amanda Soderlind

Video Transcription

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Welcome to this lesson on neurons. Today we will be giving a brief introduction into the structure and function of neurons, and the role they play in the nervous system. So the nervous system, first of all, is a body system that collects, interprets, and responds to information about the environment. And neurons are nerve cells. So these are the cells that allow the nervous system to collect information, interpret information, and respond to that information or stimuli from the environment.

So we actually have three different types of neurons that play important roles in our nervous system functioning. So the first type of neuron we're going to talk about are sensory neurons. So the purpose of sensory neurons or the function of a sensory neuron is to collect information. And sensory neurons are collecting information about stimuli. So any sort of information about the environment around you, they're going to be able to collect that information.

And sensory neurons can be found throughout the body. And they can sense information like temperature. They can sense information about the chemicals in your extracellular fluid, light, et cetera. So we have various different types of sensory neurons that allow us to collect information about different types of stimuli.

Interneurons are the next type of neuron in our nervous system. So interneurons are neurons found in the central nervous system, which includes the brain and also the spinal cord. So interneurons are found in the central nervous system. And basically, they receive information that was collected from sensory neurons. And then they process that information.

Motor neurons are the third type of neuron in our nervous system. So motor neurons, their function is to relay information to muscles or glands. And then these muscles and glands are going to carry out some sort of response depending on the information that they receive.

So what we're going to do here is label this diagram of a neuron. And then we're going to give you an example of how sensory neurons, interneurons, and motor neurons work together in order to help collect, interpret, and respond to information. So this right here is a drawing of a neuron. So we're going to go ahead and label the different parts of the neuron.

This part right here is called the dendrite. And this is actually the cell body of our neuron. And we have the nucleus in the middle.

So this section as a whole here is called the input zone. And the input zone is the location where information enters the neuron. So it'll enter through the dendrites and travel in towards the cell body.

And then we actually have a little location here called the trigger zone. So then the information will travel towards the trigger zone, and then towards the axon. So this long, slender part of the neuron is called the axon. So information is coming in through the dendrites, through the cell body, down to the trigger zone, and along the axon. So we call this part the conducting zone.

So information is traveling this way. So once it gets down to the axon, it travels through the axon endings. And then this part is called the output zone. So this is just showing you how information is traveling from the input zone, along the conducting zone, and then to the output zone.

Now at the end of this output zone-- let me get a different color here-- we might have another neuron here. And this neuron has its dendrites, axon, and axon endings. So then the information can then be relayed from the axon endings of this neuron to the dendrites of this neuron. And that message will be carried through this neuron to the next neuron. Or it could also be passed on to a muscle cell or to a gland cell to relay information as well.

So let's give you an example of how these different types of neurons work together in order to collect, interpret, and respond to information. So let's say that you're outside playing catch with a friend. And your friend throws the ball to you. So sensory neurons would allow you to be able to collect that information. You would be able to see that the ball is coming towards you. So sensory neurons would allow you to collect that information.

That information would then be sent to interneurons in your central nervous system. And your central nervous system would then determine what an appropriate response would be. So let's say that your central nervous system determines that an appropriate response would be to lift your arms up and to catch the ball.

That information is then sent to motor neurons, which relay that information to muscles or glands. So if the central nervous system decides that you should lift your arms to catch the ball, that information would then be sent to the muscles in your arms. You'd be able to lift your arms up and then catch the ball. So that's kind of how those three types of neurons work together to collect, interpret, and respond to stimuli.

So this lesson has been an overview on neurons.

Terms to Know

A part of a neuron that conducts signals away from the cell body and on to another cell.


A part of a neuron that receives incoming information.


A type of neuron in the central nervous system that receives incoming sensory information and relays information to motor neurons.

Motor Neuron

A type of neuron that communicates with gland or muscle cells which then carry out a response as determined by the brain.

Nervous System

A body system that collects, interprets and responds to stimuli from the environment.


A nerve cell responsible for relaying information throughout the nervous system.

Sensory Neuron

A type of neuron that collects data about stimuli in the environment and sends the information to the brain.