What is the Difference Between Myelinated and Unmyelinated Nerve Fibres?

Myelinated and unmyelinated nerve fibers are two types of nerve fibers that differ in their structure and function. Here are the key differences between them:

• Myelin Sheath: Myelinated nerve fibers have a myelin sheath, which is an insulating and protective layer that covers the axon and is produced by Schwann cells. Unmyelinated nerve fibers do not have this myelin sheath.
• Diameter: Myelinated nerve fibers generally have larger axons (about 0.5-20µm) compared to unmyelinated nerve fibers (about 0.5µm).
• Schwann Cells: In myelinated fibers, Schwann cells wrap tightly around and spiral along the length of the axons, while in unmyelinated fibers, Schwann cells do not wrap around the axons but are only present in the groove.
• Speed of Nerve Impulses: Myelinated nerve fibers are capable of transmitting nerve impulses much more rapidly than unmyelinated nerve fibers.
• Location: Myelinated nerve fibers are typically found in the white matter of the brain and spinal cord, while unmyelinated nerve fibers are present in the autonomic nervous system and grey matter.
• Other Structural Features: Myelinated nerve fibers have two sheaths in the axis of the cylinder, while unmyelinated nerve fibers have only one sheath in the axis of the cylinder.

Unmyelinated nerve fibers are found in certain parts of the autonomic nervous system and small axon neurons in the central nervous system. They play an important role in transmitting cutaneous and visceral peripheral signals to the central nervous system, processing sensory and autonomic information.

Comparative Table: Myelinated vs Unmyelinated Nerve Fibres

Here is a table comparing the differences between myelinated and unmyelinated nerve fibers:

Myelinated nerve fibers are found in the white matter of the nervous system, while unmyelinated nerve fibers are found in the grey matter. Myelinated nerve fibers have a myelin sheath that protects and insulates the nerve fiber, allowing for faster nerve impulse transmission. On the other hand, unmyelinated nerve fibers do not have a myelin sheath, which results in slower nerve impulse transmission.