Question

Mention the exact location of the following: Myelin sheath

Answer 1

Hint: Myelin sheath helps in the conduction of electrical impulses also known as the action potential away from the nerve cell body. Myelin sheath is a long and thin projection of nerve cells or neurons in the vertebrates. Axons perform the transmission of information to different neurons, muscles, and glands.

Complete answer:
-In the brain and spinal cord myelin is an insulating layer that forms around the nerves. It is usually made up of protein and fatty substances.
-It helps in the transmission of electrical impulses very quickly and efficiently with the nerve cells. If there is any damage caused to the myelin, the impulses slow down. Such a condition can cause the disease- multiple sclerosis.
Location of Myelin sheath
-In both the central nervous system and peripheral nervous system myelin sheath can be found.
-The myelin sheath can be found around the axons of the neurons present in the brain, spinal cord, and optic nerve in the central nervous system.
-Here, it performs the action of separations of various axons that are packed together in the brain or spinal cord.
-In the outer grey matter of the spinal cord, the myelinated nerve fibers are found whereas in the brain its opposite, in the inner side of the brain, grey matter containing myelinated nerve fibers is found.
-The myelin sheath can be found around the axons and dendrites of the motor neurons in the peripheral nervous system.
-The central and peripheral processes of the sensory neurons are surrounded by the myelin sheath.
All the spinal nerves which are present are surrounded by a layer of the myelin sheath.

Additional Information: The histological structure as well as biochemical structure both use to study the structure of the myelin sheath. Both of these structures are explained below.
Histological structure
-The histological structure of the myelin sheath can be studied under the light microscope after proper tissue preparation. for the fixation of the nervous tissue aldehyde such as formalin is used for the light microscope
-The stained slide of the prepared tissue viewed under the light microscope. In the horizontal cut sections, myelin sheaths appear as pink rings when they take the hematoxylin stain and surround the axons in the nervous tissue. Myelin sheath appears as vertical projections in the vertical cut sections of the nervous tissue side by side with the long axons or nerve fibers
Biochemical Structure
Myelin sheath is composed of lipids, proteins, and water. The total mass of the myelin sheath is made by the water i.e around 40%.
-Around 60 to 75% of the total dry mass is made by the lipids and protein covers 15 to 30% of the total biochemical content in the myelin sheath.

Note: Myelin sheath is a layer of lipids that surround the cellular process of the neurons and provide electrical insulation from the surrounding fluid.
The function of the Myelin sheath
1) Increase the speed of conduction
2) Protection of axons
3) Provide nutrition to the nerve fibers.
4) Provide electrical insulation to the nerve fiber.