Difference Between Myelinated and Unmyelinated Neurons

Neurons play an inevitable function in the functioning of our bodily functions. Myelinated and unmyelinated neurons are a pair of neurons that perform the crucial function of transmitting and conducting electric signals across the body. However, they have several differences in their appearance and functioning. 

Myelinated vs Unmyelinated Neurons 

The main difference between myelinated and unmyelinated neurons is that myelinated neurons comprise a myelin sheath surrounding the axon. On the other hand, an unmyelinated neuron is devoid of any myelin sheath. Nodes and internodes are clearly visible in the myelinated neurons. On the other hand, nodes and internodes are absent in the unmyelinated neurons.

Myelinated vs Unmyelinated Neurons

Myelinated Neurons refer to a neuron wherein the axon is enclosed by a layer of Schwann cell membranes. Myelinated neurons perform the function of transmitting signals from one part of the body to another. Thus, they play a fundamental role in information transmission. Moreover, myelinated neurons mature at the age of two years in the brain. 

Unmyelinated neurons are nerve cells that have the primary potential to transmit impulses in the form of electric signals. The Schwann cells are not wrapped around axons. Instead, the cells are arranged in the shape of a groove. In addition, the unmyelinated fibres comprise both nonpeptidergic and peptidergic C-fibre axons. 

Comparison Table Between Myelinated and Unmyelinated Neurons 

Parameters of ComparisonMyelinated NeuronsUnmyelinated Neurons
DefinitionMyelinated neurons comprise a myelin sheath surrounding the axon.Unmyelinated neuron is devoid of any myelin sheath.
Conduction of Impulses There is a faster transmission and conduction of electrical signals in the case of myelinated neurons.There is a slower transmission and conduction of electrical impulses in the case of unmyelinated neurons. 
Appearance Myelinated neurons have a white appearance in a fresh state.Unmyelinated neurons have a gray appearance in the fresh state. 
Nodes and Internodes Nodes and internodes are clearly visible in the myelinated neurons.Nodes and internodes are absent in the unmyelinated neurons. 
Found inMyelinated neurons are found in the central nervous system and the cranial nervous system.Unmyelinated neurons are found in the autonomic nervous system.

What are Myelinated Neurons?

Myelinated Neurons refer to a neuron wherein the axon is enclosed by a layer of Schwann cell membranes, also known as sheath. There are several advantages of the prevalence of a myelin sheath. The most prominent advantage is the prevalence of faster conduction of action potential. Thus, messages are able to transfer at a faster pace.

The myelinated neurons are found in the peripheral nervous system and the white substances of the central nervous system. Most importantly, the sensory and motor neurons are commonplace in the peripheral nervous system and the central nervous system. The myelin sheath also provides insulation and protection to the neurons.

The formation of myelin takes place in the brain, spinal cord, and optic nerve by oligodendrocytes. Myelinated neurons perform the function of transmitting signals from one part of the body to another. Thus, they play a fundamental role in information transmission. In addition, myelinated neurons comprise approximately 80% lipids.

Myelinated neurons mature at the age of two years in the brain. The Schwann cells are responsible for producing myelinated neurons for peripheral axons. However, it is the duty of oligodendrocytes to produce myelinated neurons for central axons. To conclude, myelinated neurons have an edge over unmyelinated neurons due to the presence of the myelin sheath.

What are Unmyelinated Neurons?

Unmyelinated Neurons refers to those neurons that are devoid of a layer of myelin sheath. Due to the absence of a myelin sheath, unmyelinated neurons are relatively slower in the transmission of signals from one part of the body to another. Unmyelinated neurons are found in the gray matter of the nervous system and the peripheral nervous system.

Unmyelinated neurons are also known as Type C neurons. The unmyelinated fibres comprise both nonpeptidergic and peptidergic C-fibre axons. The location of unmyelinated neurons is usually the hairy and glabrous skin. Moreover, the axis cylinder of unmyelinated neurons consists of a singular sheath instead of multiple ones. 

The color and appearance of unmyelinated neurons is usually gray at first appearance. The Schwann cells are not wrapped around axons. Instead, the cells are arranged in the shape of a groove. In addition, unmyelinated neurons don’t have prominent nodes and internodes. The commonplace location of unmyelinated neurons is the autonomic nervous system.

Thus, unmyelinated neurons are nerve cells that have the primary potential to transmit impulses in the form of electric signals. The production of collateral fibres is absent in the case of unmyelinated nerve fibres. However, the absence of unmyelinated neurons connotes a slower transmission and conduction of impulses. 

Main Differences Between Myelinated and Unmyelinated Neurons 

  1. Myelinated neurons comprise a myelin sheath surrounding the axon. On the other hand, an unmyelinated neuron is devoid of any myelin sheath.
  2. There is a faster transmission and conduction of electrical signals in the case of myelinated neurons as compared to unmyelinated neurons. 
  3. Myelinated neurons have a white appearance in a fresh state. In contrast, unmyelinated neurons have a gray appearance in the fresh state. 
  4. Nodes and internodes are clearly visible in the myelinated neurons. On the other hand, nodes and internodes are absent in the unmyelinated neurons. 
  5. Myelinated neurons are found in the central nervous system and the cranial nervous system. In contrast, unmyelinated neurons are found in the autonomic nervous system.

Conclusion

Thus, myelinated and unmyelinated neurons vary on several grounds. There are visible differences in the appearance, function, transmission speed, and presence of myelin sheath in both myelinated and unmyelinated neurons. The formation of myelin takes place in the brain, spinal cord, and optic nerve by oligodendrocytes. 

Myelinated neurons comprise approximately 80% lipids. However, there is no such case in unmyelinated neurons. Unmyelinated neurons are found in the gray matter of the nervous system and the peripheral nervous system. To conclude, myelinated and unmyelinated neurons have considerable differences. 

References

  1. https://journals.physiology.org/doi/full/10.1152/advan.00045.2003 
  2. https://www.easybiologyclass.com/difference-between-myelinated-and-unmyelinated-neurons/ 
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