Britannica
Sources used in this answer
How are gray matter and white matter different in the central nervous system?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
nervous system
In a myelinated axon, the myelin sheath prevents the local current (small black arrows) from flowing across the membrane. This forces the current to travel down the nerve fibre to the unmyelinated nodes of Ranvier, which have a high concentration of ion channels. Upon stimulation, these ion channels propagate the action potential (large green arrows) to the next node. Thus, the action potential jumps along the fibre as it is regenerated at each node, a process called saltatory conduction. In an unmyelinated axon, the action potential is propagated along the entire membrane, fading as it diffuses back through the membrane to the original depolarized region.
In the central nervous system, gray matter and white matter are distinguished primarily by their cellular composition and functional roles.1
- Gray Matter: This tissue is composed of large concentrations of neurons, including cell bodies, dendrites, and synapses. It serves as the processing center where information is received and coordinated. In the spinal cord, for example, gray matter is organized into distinct cellular layers called laminae that handle specific sensory and motor functions.12
- White Matter: This tissue consists mainly of myelinated axons bundled into tracts. Its whitish appearance is due to the myelin sheath surrounding these fibers. Functionally, white matter acts as the communication network, relaying signals between different areas of the brain and the rest of the central nervous system.31
Together, these two types of tissue, supported by glia, form the interconnected networks necessary for the nervous system to process information and regulate bodily functions.1