Difference Between Sensory and Motor Neurons

The study and practice of biology helps us to analyze the human body adequately. The nervous system is a critical part of our body that needs to be understood in order to lead a prosperous life. Neurons form the basic foundation for receiving sensory inputs, instructing the muscle through motor commands, and sending the signals back to the brain to initiate actions. Talking about the types of neurons on the basis of functions and structure, the central nervous system comprises two types of neurons- Sensory and Motor Neurons. We’ll be looking at the difference between sensory and motor neurons. The difference between sensory and motor neuron has been tabulated below:


Sensory Vs Motor Neurons

Bases

Sensory Neurons

Motor Neurons 

Function

When we compare motor neuron vs sensory neuron, the main function of  Sensory Neurons is to send sensory signals from sensory organs to the central nervous system.

Motor Nerves are responsible for sending motor commands from the central nervous system to the sensory organs to initiate actions.

Location

Dorsal root ganglion of the spinal nerve in the sense organs.

Ventral root ganglion of the spinal cord in muscles and glands.

Polarity

Sensory neurons are uni-polar

Motor neurons are multi-polar

Structure/Length of the Axon


Short axon

Long axon

Number of Dendrons

One long dendron 

Many dendrons 

Quantity

10 million sensory neurons

Half a million motor neurons


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We hope that it’s pretty much clear how sensory and motor neurons differ from each other. Now, we will be looking forward to our next section i.e. difference between sensory and motor neurons on the basis of their structure.  


Structural Differences: Difference Between Sensory Neuron and Motor Neuron

Although the core function of the neurons differentiate between sensory neuron and motor neuron, both the neurons also differ in structure. Let’s look into the structural difference between the sensory neuron and motor neurons and what makes them different from each other.


Sensory Vs Motor Nerves: Difference Between Sensory Neuron and Motor Neuron

To differentiate between sensory neuron and motor neuron, we will be defining the structure of both the neurons one by one.   


Sensory Nerves Vs Motor Nerves

Structure of Sensory Neurons: 

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  • Sensory neurons conduct signals from sensory organs to the CNS. Sensory Neurons arise from the dorsal root ganglion, which are specialized clusters present at the dorsal roots of the spinal cord.

  • Sensory neurons lack distinct axons and dendrites.

  • Sensory neurons possess receptors.

  • The soma of the sensory neurons possesses a nucleus and other cell organelles.

  • A synaptic junction with second-order sensory neurons is formed as the central branch extends from soma to the posterior horn of the spinal cord.

  • These neurons are also known as pseudo unipolar neurons.


Structure of Motor Neurons

To understand the difference between sensory neuron and motor neuron in a better way, let's learn the structure of Motor neurons.

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  • Motor nerves transmit the signals from the CNS to the sensory organs and thus, help in initiating actions.

  • These neurons are located at the ventral root ganglion of the spinal cord.

  • Motor neurons consist of long axon and multiple dendrons.

  • They lack receptors.

  • These neurons are also known as multipolar neurons.

These are the main differences between sensory and motor nerves. 

We hope that the functional difference between sensory nerve and motor nerve is pretty much clear. Thus, we will be moving towards our next section that is to differentiate sensory nerves and motor nerves on the basis of the functions they perform. 


Differentiate Between Sensory and Motor Neurons on the Basis of Functions

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Till now, we have just discussed the basic functions and how to differentiate between sensory neuron and motor neuron. But, the functions of sensory and motor neurons are much vast. Let's compare and contrast sensory and motor neurons on the basis of the function they perform in the human body. 

For the difference between sensory and motor neurons, let’s first look at the functions performed by sensory neurons.


Functions of Sensory Neurons

We will see the difference between sensory and motor nerves on the basis of function.

We know, sensory neurons transmit the signal from the sense organs to the CNS in the form of sensory signals. Let’s look at some of the most important functions performed by sensory neurons in the human body.


Controlling the Heartbeat and Blood Circulation

The sensory receptors in the blood vessels are responsible for registering blood pressure. Sensory neurons can be found in the aorta, carotid arteries, pulmonary artery, capillaries in the adrenal gland, and the tissues of the heart itself, from where the signals are sent to the medulla and thus, help in controlling BP and blood circulation.


Effects in Neuritis

Inflammation of sensory neurons results in the sensation of burning, tingling, or stabbing pain. These are even worse at night and are aggravated by temperature change.


Taste Buds

Taste receptor cells on our tongues form a group of 50 to 150. These cells respond to the chemicals present in the food and thus, form taste buds, which help us in differentiating among the food items of different tastes. 


Fun Fact: 

An average adult can have more than 8,000 taste buds!            

Sensory neurons and motor neurons work in coordination which each helps in the functioning of our body. So, if you are able to taste something, it’s because of the harmonized working of both the neurons.

We hope that the difference between sensory nerve and motor nerve is now clear. The topic is pretty much simple and just needs a bit of understanding. The difference between sensory and motor nerves can be well understood with the table in the first section.   

FAQ (Frequently Asked Questions)

1. Explain the Structure of Sensory Neurons.

To understand the difference between sensory nerve and motor nerve, it is important that we understand the structure of sensory neurons. Sensory neurons conduct signals from sensory organs to the CNS. Sensory Neurons arise from the dorsal root ganglion, which are specialized clusters present at the dorsal roots of the spinal cord. Sensory neurons lack distinct axons and dendrites. The soma of the sensory neurons possesses a nucleus and other cell organelles. A synaptic junction with second-order sensory neurons is formed as the central branch extends from soma to the posterior horn of the spinal cord. These neurons are also known as pseudo unipolar neurons. In the blog, we have already explained the difference between sensory and motor nerves. You can refer to the above-given sections for more information. 

2. What are the Functions of Sensory Neurons?

The following are the functions performed by sensory neurons:


Controlling the Heartbeat and Blood Circulation

The sensory receptors in the blood vessels are responsible for registering blood pressure. Sensory neurons can be found in the aorta, carotid arteries, pulmonary artery, capillaries in the adrenal gland, and the tissues of the heart itself, from where the signals are sent to the medulla and thus, help in controlling BP and blood circulation.


Effects in Neuritis

Inflammation of sensory neurons results in the sensation of burning, tingling, or stabbing pain. These are even worse at night and are aggravated by temperature change.


Taste Buds

Taste receptor cells on our tongues form a group of 50 to 150. These cells respond to the chemicals present in the food and thus, form taste buds, which help us in differentiating among the food items of different tastes.