Why are dendrites unmylined

Difference between myelinated and non-myelinated axons

Key difference - myelinated and non-myelinated axons

The nervous system is responsible for receiving and distributing sensory signals throughout the body. Neurons are the building blocks or basic cells of the nervous system. Neurons are responsible for transmitting the correct information or commands to the correct position of the body. A neuron has three main components: cell bodies, dendrites, and an axon. Dendrites receive an electrical signal and pass it on to the axon. Axon transmits the signal to the next neuron. Axons are insulated with a layer of electrical insulation called the myelin sheath. The myelin sheath is made up of a fatty material called myelin. The myelin sheath is made by special cells in the peripheral nervous system called Schwann cells. Myelin is produced by Schwann cells, and the myelin sheath is formed in a spiral around the axon. The myelin sheath increases the speed of signal transmission, but not all axons are myelinated. There are two types of neurons based on the presence and absence of the myelin sheath around the axon. They are myelinated neurons and non-myelinated neurons. Myelinated neurons have myelinated axons and non-myelinated neurons have non-myelinated axons. The main difference between myelinated and non-myelinated axons is that Myelinated axons have a myelin sheath, while non-myelinated axons do not have a myelin sheath.

1. Overview and main difference
2. What are myelinated axons?
3. What are non-myelinated axons?
4. Side by Side Comparison - Tabular Myelinated and Unmyelinated Axons
5. Summary

What are myelinated axons?

An axon is a long, thin projection of a nerve cell (neuron). It conducts electrical impulses from the neuron cell body to the chemical synapse. Axons are also known as nerve fibers. Nerve impulses are continuously transmitted along the axons without changing their path. Cells of the peripheral nervous system support the transmission of nerve impulses via neurons.

Schwann cells are a type of special glial cell that form myelin sheaths around the axons. The myelin sheath is an electrical insulating layer made up of myelin protein and lipids, including cholesterol, glycolipids, and phospholipids. Neurons whose axons are covered with myelin sheaths are called myelinated neurons. Axons that are protected with myelin sheaths are called myelinated axons. In general, larger axons are covered with myelin sheaths and are known as myelinated fibers or medullated fibers. Thicker axons have a thicker myelin layer and longer internodes. When axons are myelinated, they look white.

The myelin sheath comes from Schwann cells, and Schwann cells hold gaps as they wrap around the axon. These gaps are not myelinated. Hence, these gaps disrupt the myelin sheath and they are called the Ranvier knots. When axons are myelinated, the conduction of nerve impulses along the neurons is faster and the loss of impulses during conduction is avoided.

What are non-myelinated axons?

When axons are not protected with myelin sheaths, they are known as non-myelinated axons. Typically, thinner axons less than a micron in diameter do not have myelin sheaths. These axons or nerve fibers are also known as non-myelinated or non-medullated fibers. The conduction of the nerve impulse through non-myelinated axons is slower than with myelinated axons. There is also the possibility of losing the pulse while on the line.

What is the difference between myelinated and non-myelinated axons?

Myelinated vs non-myelinated axons

Myelinated axons are the neuron axons that are covered with myelin sheaths.Non-myelinated axons are the axons that are not covered with myelin sheaths.
Speed ​​of nerve impulses
The conduction of nerve impulses is faster in myelinated axons.The transmission of nerve impulses is slower in non-myelinated axons.
Loss of momentum
Loss of momentum is avoided with myelinated axons.There is a greater chance of losing momentum.
thickness
Myelinated axons are thicker than non-myelinated axons.Non-myelinated axons are thinner than myelinated axons.

Summary - Myelinated vs non-myelinated axons

Axon is a thread-like extension of a neuron. It extends from the soma of the neuron. Axons carry electrical signals away from the neuron. In some neurons, axons are wrapped in special glial cells called Schwann cells. Schwann cells form an electrical insulating layer around the axon known as the myelin sheath and increase the speed of signal transmission. Some axons do not have myelin sheaths. They are known as non-myelinated axons. The axons that are covered with a myelin sheath are called myelinated axons. This is the difference between myelinated and non-myelinated axons.

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References:

1. "Myelin. Wikipedia. Wikimedia Foundation, July 13, 2017. Web. Available here. July 19, 2017.
2. Morell, Pierre. "The myelin sheath." Basic Neurochemistry: Molecular, Cellular, and Medical Aspects. 6th edition. US National Library of Medicine, January 1, 1999. Web. Available here. 18th July 2017.

Image courtesy:

1. "Complete neuron cell diagram de" by LadyofHats - own work. Image renamed from Image: Complete Neuron Cell Diagram.svg (Public Domain) via Commons Wikimedia
2. "Myelinated Unmylinated Neurons" By Nick Gorton - (CC BY-SA 3.0) via Commons Wikimedia