Science Olympiad Anatomy And Physiology Practice Test

The Schwann cell is the primary cell responsible for producing myelin in the peripheral nervous system (PNS). Myelin is a fatty substance that forms a protective sheath around the axons of neurons, which enhances the speed of electrical signal conduction along the nerve fibers. Schwann cells wrap around the axons, creating segments of myelin sheaths separated by nodes of Ranvier, where the axonal membrane is exposed. This arrangement facilitates rapid signal transmission through a process known as saltatory conduction. In contrast, neurons are the specialized cells that transmit impulses and do not have the ability to produce myelin. Astral cells could be referring to astrocytes, which are a type of glial cell in the central nervous system and are involved in supporting neurons, but they do not produce myelin. Overall, while glial cells encompass a variety of support cells in both the central and peripheral nervous systems, Schwann cells specifically are recognized for their role in myelination within the PNS.