What substance is produced by Schwann cells in the peripheral nervous system?

• A. Neurotransmitters
• B. Myelin sheath
• C. Dendritic extensions
• D. Axon terminals

Answer: (B)

Schwann cells are specialized glial cells in the peripheral nervous system that are primarily responsible for the formation of the myelin sheath. This sheath is a fatty layer that envelops nerve fibers, facilitating the rapid transmission of electrical impulses along the axon. The myelin sheath not only increases the speed of signal conduction but also provides insulation, protecting the axon from interference by other electrical signals.

By producing myelin, Schwann cells significantly enhance the efficiency of neural communication. This is particularly important in the peripheral nervous system, where long distances between neurons require quick and efficient signal propagation. Without myelin produced by Schwann cells, nerve impulses would travel much more slowly, leading to impaired neuronal function.

Other substances listed, such as neurotransmitters, dendritic extensions, and axon terminals, serve different roles in neural communication and structure but are not directly produced by Schwann cells. Neurotransmitters are typically released by neurons at synapses, while dendritic extensions and axon terminals are parts of the neuron itself, involved in receiving and transmitting signals, respectively. Thus, the production of the myelin sheath by Schwann cells is essential for the proper functioning of the peripheral nervous system.