What is the fatty tissue layer that segments axons to speed neural transmission?

• A. Schwann cell
• B. Myelin sheath
• C. Node of Ranvier
• D. Cytoplasm

Answer: (B)

Insulating the axon with a fatty coating speeds how quickly signals travel. This fatty layer, called the myelin sheath, wraps around the axon and prevents current from leaking, which increases conduction speed. The sheath is formed by Schwann cells in the peripheral nervous system and by oligodendrocytes in the central nervous system. Between these myelin segments are the nodes of Ranvier, gaps where ion channels sit to refresh the electrical signal, allowing the action potential to jump from node to node in a process known as saltatory conduction. So the myelin sheath is the fatty tissue layer that segments and speeds transmission, while the other terms refer to the cells that make the myelin, the gaps between segments, or the interior of the cell.