Myelin is formed by Schwann cells in the peripheral nervous system (PNS) and oligodendrocytes in the central nervous system (CNS). Each Schwann cell forms a single myelin sheath around an axon. Myelin itself forms by the spiral wrapping around an axon of an enormously expanded glial plasma membrane that then compacts.
Similarly, you may ask, how does myelin production in the CNS differ from that in the PNS?
CNS myelin is produced by special cells called oligodendrocytes. PNS myelin is produced by Schwann cells. The two types of myelin are chemically different, but they both perform the same function to promote efficient transmission of a nerve impulse along the axon.
Also, what is the main component of myelin? Myelin is composed of about 40% water and the dry mass is composed of about 80% lipids and 20% protein. The mainly lipid composition of the myelin gives it a white hue, hence the reference to the brain’s “white matter.” The main lipid found in myelin is a glycolipid called galactocerebroside.
Keeping this in consideration, how are nerve cells Ensheathed with myelin in the CNS?
In the PNS, cells called Schwann cells produce and maintain the myelin whereas, in the CNS, glial cells called oligodendrocytes produce and maintain the myelin. In Multiple Sclerosis, the myelin is destructively removed from around the axon which slows down nerve impulses in a process known as demyelination.
Does myelin produce cerebrospinal fluid?
Ependymal cells produce cerebrospinal fluid that cushions the neurons. Glial cells of the (b) peripheral nervous system include Schwann cells, which form the myelin sheath, and satellite cells, which provide nutrients and structural support to neurons.
19 Related Question Answers Found
What is the role of myelin?
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. The main function of myelin is to protect and insulate these axons and enhance their transmission of electrical impulses.
How is myelin produced?
Myelin is made by two different types of support cells. In the central nervous system (CNS) — the brain and spinal cord — cells called oligodendrocytes wrap their branch-like extensions around axons to create a myelin sheath. In the nerves outside of the spinal cord, Schwann cells produce myelin.
What glial cells produce myelin?
The glial cells that produce myelin in the central nervous system are called oligodendrocytes. In the peripheral nervous system, the myelin producing cells are called Schwann cells. Each oligodendrocyte can supply myelin for the axons of several nerve cells and each axon can be supplied by several oligodendrocytes.
What produces myelin in the PNS?
Myelin is present in the central nervous system (CNS) and peripheral nervous system (PNS); however only the central nervous system is affected by MS. CNS myelin is produced by special cells called oligodendrocytes. PNS myelin is produced by Schwann cells.
What are glial cells?
Medical Definition of Glial cell The glial cells surround neurons and provide support for and insulation between them. Glial cells are the most abundant cell types in the central nervous system. Types of glial cells include oligodendrocytes, astrocytes, ependymal cells, Schwann cells, microglia, and satellite cells.
Do Schwann cells Myelinate axons in the CNS?
Myelin is formed by Schwann cells in the peripheral nervous system (PNS) and oligodendrocytes in the central nervous system (CNS). Each Schwann cell forms a single myelin sheath around an axon. In contrast, each oligodendrocyte forms multiple sheaths (up to 30 or more) around different axons (Figure 1).
Is myelin made of glial cells?
Myelin is composed of multiple concentric layers of glial plasma membrane (oligodendrocytes in the CNS, Schwann cells in the PNS) wrapped around axons. The purpose of myelination is to increase axonal conduction velocity.
What is the impact of myelin on the human nervous system?
Much like the insulation around the wires in electrical systems, glial cells form a membraneous sheath surrounding axons called myelin, thereby insulating the axon. This myelination, as it is called, can greatly increase the speed of signals transmitted between neurons (known as action potentials).
What happens if myelin sheath is damaged?
When the myelin sheath is damaged, nerves do not conduct electrical impulses normally. However, if the sheath is severely damaged, the underlying nerve fiber can die. Nerve fibers in the central nervous system (brain and spinal cord) cannot fully regenerate themselves. Thus, these nerve cells are permanently damaged.
How does myelin speed up transmission?
Most nerve fibres are surrounded by an insulating, fatty sheath called myelin, which acts to speed up impulses. The myelin sheath contains periodic breaks called nodes of Ranvier. By jumping from node to node, the impulse can travel much more quickly than if it had to travel along the entire length of the nerve fibre.
What causes damage to myelin sheath?
Multiple sclerosis (MS) is the most common demyelinating disease of the central nervous system. In this disorder, your immune system attacks the myelin sheath or the cells that produce and maintain it. This causes inflammation and injury to the sheath and ultimately to the nerve fibers that it surrounds.
Why Saltatory conduction is faster?
Myelin greatly speeds up action potential conduction because of exactly that reason: myelin acts as an electrical insulator! Myelin sheath reduces membrane capacitance and increases membrane resistance in the inter-node intervals, thus allowing a fast, saltatory movement of action potentials from node to node.
What is the difference between oligodendrocytes and Schwann cells?
Schwann cells myelinate axons in the peripheral nervous system, while Oligodendrocytes myelinate axons in the central nervous system. Another interesting difference is that when Schwann cells myelinate, their cell body’s actually wrap around the axon. Oligodendrocytes secrete the myelin sheaths around the axons.
Why are Unmyelinated axons slower?
This means that unmyelinated axons are slower in the conduction of electric signals, and therefore information, than myelinated axons. This is important because there is a disease whereupon the body’s own immune system attacks the myelin sheath around the axons in the central nervous system.
What are the support cells of the nervous system?
Nervous tissue, one of the four main tissue types, is composed of neurons and supporting cells called neuroglia. Neuroglia are also called “glial cells.”
How many axons does a nerve have?
Axon. Axon, also called nerve fibre, portion of a nerve cell (neuron) that carries nerve impulses away from the cell body. A neuron typically has one axon that connects it with other neurons or with muscle or gland cells. Some axons may be quite long, reaching, for example, from the spinal cord down to a toe.
What color is white matter?
White matter is the tissue through which messages pass between different areas of gray matter within the central nervous system. The white matter is white because of the fatty substance (myelin) that surrounds the nerve fibers (axons).
How much myelin is in the brain?
With the growing complexity of the nervous system, there is a relative increase in the white matter of vertebrates. In humans, around 40% of the brain contains white matter comprising densely packed fibres, of which myelin is a main component (50–60% dry weight of the white matter) (Morell and Norton, 1980).
What are the components of the myelin sheath?
The myelin sheath is a greatly extended and modified plasma membrane wrapped around the nerve axon in a spiral fashion [1]. The myelin membranes originate from and are a part of the Schwann cells in the peripheral nervous system (PNS) and the oligodendroglial cells in the central nervous system (CNS) (see Chap. 1).