What is the fatty insulating layer around the axon called?

• A. Myelin Sheath
• B. Node of Ranvier
• C. Dendrite
• D. Synapse

Answer: (A)

The fatty insulating layer around the axon is the myelin sheath. It wraps around many axons in both the central and peripheral nervous systems, made of lipid-rich material that reduces leakage of electrical current and lowers the membrane’s capacitance. This insulation speeds up signal transmission through saltatory conduction, as the action potential effectively hops from one gap in the myelin (the Node of Ranvier) to the next, so the neuron can fire more quickly. Myelin is produced by oligodendrocytes in the brain and spinal cord and by Schwann cells in the peripheral nerves. Dendrites are the neuronal structures that receive signals, and synapses are the junctions between neurons; the Node of Ranvier is a gap in the myelin sheath, not the insulating layer itself.