Myelin in the PNS is _.
A) released from a neuron and travels to another neuron. B) made of lipids and proteins that wrap around an axon. C) produced in response to bacterial infection. D) a chromatophilic substance that fills Oligodendrocytes.
The correct answer and explanation is:
The correct answer is B) made of lipids and proteins that wrap around an axon.
Myelin in the peripheral nervous system (PNS) is a fatty substance composed of lipids and proteins that wraps around the axons of neurons. This structure is formed by Schwann cells, a type of glial cell in the PNS. The primary function of myelin is to increase the speed of electrical signal transmission along the axon by insulating it and preventing the loss of electrical current. Myelin helps to ensure that nerve impulses travel efficiently from one part of the body to another.
In the PNS, Schwann cells wrap around the axon in a spiral manner, forming segments of myelin, each separated by nodes called the Nodes of Ranvier. These nodes allow for the process of saltatory conduction, where the electrical impulse jumps from one node to the next, significantly speeding up signal transmission compared to continuous conduction along unmyelinated axons.
Myelin is essential for the proper functioning of the nervous system. Without it, nerve impulses would travel much more slowly, impairing the coordination and communication between nerve cells. Myelination begins early in development and continues through adolescence. In some neurological diseases, such as multiple sclerosis, the myelin sheath becomes damaged, which leads to a slower or blocked transmission of nerve impulses, resulting in a range of symptoms like muscle weakness and coordination problems.
To summarize, myelin in the PNS is formed by Schwann cells and serves as an insulating layer that enhances the speed and efficiency of electrical signal conduction along axons.