12 Difference Between Myelinated And Unmyelinated Neurons (Nerve Fiber) With Examples

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Neurons are electrically excitable cells in the human bodies that communicate with other cells through specialized connection referred to as Synapses. Each neuron has a cell body with many minute branched short protoplasmic extensions referred to as dendrites and an elongated unbranched protoplasmic extension referred to as Axon.

What Are Myelinated Nerve Fibers?

Myelinated Nerve Fibers are nerve fibers that are insulated by a myelin sheath. The myelin sheath is a protective covering that surrounds fibres called axons, the long thin projections that extend from the main body of a nerve cell or neuron. This sheath is composed of protein and lipids (fatty substance), that insulates the nerve cell axons so as to increase the speed at which information travels from one nerve cell body to another for example from a nerve cell body to a muscle.

Majority of neurons in the central and peripheral nervous system are Myelinated. In the central nervous system, myelin is produced by oligodendroglia, whereas in the peripheral nervous system, it is produced by Schwann cells.

Majority of neurons in the central and peripheral nervous system are Myelinated. In the central nervous system, myelin is produced by oligodendroglia, whereas in the peripheral nervous system, it is produced by Schwann cells.

The main function of myelin is to protect and insulate these axons and enhance their transmission of electrical impulses. A neuron with Myelinated axons can conduct the impulse at a faster speed since myelin sheath acts as the insulator that help to propagate the electrical signal faster. If myelin is damaged, the transmission of these impulses is slowed down, which is seen in severe neurological conditions such as multiple sclerosis.

Facts About Myelinated Nerve Fibers (Neuron)

  • Myelinated Nerve Fibers are nerve fibers that are insulated by a myelin sheath.
  • The nerve fibers with long axons are myelinated.
  • The axis cylinder of the myelinated nerve fibres has two sheaths.
  • Myelinated fibres show nodes and internodes.
  • The myelinated nerve fibers appear white in color.
  • The myelinated nerve fibers have nodes of Ranvier.
  • The Schwann cells wrap tightly around the nerve axon and form the myelin sheath.
  • Due to presence of nodes of Ranvier on myelinated nerve fibers, the speed of transmission of nerve impulses is high in myelinated nerve fibers. 
  • Most neurons in the central and peripheral nervous system are myelinated because they require fast conduction speed such as neuron involved in spinal reflexes.
  • Due to presence of myelin sheath, myelinated nerves do not lose the impulse during conduction.
  • In myelinated fibers electrical impulses (action potentials) travel as continuous waves.
  • Myelinated nerve fibres may give off collateral nerve fibres.

Also Read: Difference Between Sensory And Motor Neurons

What Are Unmyelinated Nerve Fibers?

Unmyelinated nerve fibers are nerve fibers that do not have a myelin sheath. Unmyelinated nerve fibers conduct impulses at low velocities. They represent the majority of peripheral sensory and autonomic fibers. They are also found in the spinal cord and brain. In Unmyelinated fibers electrical impulses (action potentials) ”hop” or propagate by saltatory conduction and can lose the nerve impulse during conduction.

Unmyelinated nerve fibers do not have nodes of Ranvier. Nodes of Ranvier are the spaces between the myelin coatings on the neuron’s axon. The nodes of Ranvier serve to facilitate the rapid conduction of nerve impulses.

Facts About Unmyelinated Nerve Fibers (Neuron)

  • Unmyelinated nerve fibers are nerve fibers that do not have a myelin sheath.
  • The short axon nerve fibers are unmyelinated.
  • The axis cylinder of unmyelinated nerve fibres has only one sheath.
  • Unmyelinated nerve fibres do not show notes and internodes.
  • The nerve fibers appear gray in color.
  • Schwann cells are not wound around the axons but simply form a groove.
  • They do not have nodes of Ranvier.
  • They do not have myelin insulations, and therefore, the speed of the transmission of the nerve impulses is low.
  • Unmyelinated neurons can be found in both the peripheral and central nervous system in the group c nerve fibers, responsible for transmission of secondary pain or itch.
  • Unmyelinated nerve fibers can lose the nerve impulse during conduction.
  • In Unmyelinated fibers electrical impulses (action potentials) ”hop” or propagate by saltatory conduction.
  • collateral fibres are not produced in Unmyelinated nerves.

Also Read: Difference Between Action Potential And Resting Potential

Difference Between Myelinated And Unmyelinated Neurons (Nerve Fiber) In Tabular Form

BASIS OF COMPARISON MYELINATED NERVE FIBER   UNMYELINATED NERVE FIBER
Description Myelinated Nerve Fibers are nerve fibers that are insulated by a myelin sheath. Unmyelinated Nerve fibers are nerve fibers that do not have a myelin sheath. 
Color The myelinated nerve fibers are white in color.   The unmyelinated nerve fibers are gray in color.  
Nodes of Ranvier The myelinated nerve fibers have nodes of Ranvier.   Unmyelinated nerve fibers do not have nodes of Ranvier.
Speed of Transmission Due to presence of nodes of Ranvier on myelinated nerve fibers, the speed of transmission of nerve impulses is high in myelinated nerve fibers.  Unmyelinated nerve fibers do not have myelin insulations, and therefore, the speed of the transmission of the nerve impulses is low.  
Location Most neurons in the central and peripheral nervous system are myelinated because they require fast conduction speed such as neuron involved in spinal reflexes. Unmyelinated neurons can be found in both the peripheral and central nervous system in the group c nerve fibers, responsible for transmission of secondary pain or itch.  
Impulse Conduction Due to presence of myelin sheath, myelinated nerves do not lose the impulse during conduction Unmyelinated nerve fibers can lose the nerve impulse during conduction.  
Axons The nerve fibers with long axons are myelinated. The short axon nerve fibers are unmyelinated.  

Also Read: Difference Between Axon And Dendrites

What is the main difference between Myelinated and Unmyelinated Nerve fiber?

Myelinated Nerve Fibers are nerve fibers that are insulated by a myelin sheath whereas Unmyelinated Nerve fibers are nerve fibers that do not have a myelin sheath.