What is the difference between the white and grey matter of the brain?

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The two main differences between white matter and grey matter are biological and functional. White matter, which forms the major bulk of the brain, is responsible for transmitting instructions and information within, to, and from the rest of the body into the grey matter. White matter is composed of fibrous axons and...

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The two main differences between white matter and grey matter are biological and functional. White matter, which forms the major bulk of the brain, is responsible for transmitting instructions and information within, to, and from the rest of the body into the grey matter. White matter is composed of fibrous axons and insulated with myelin sheathing, allowing fast communication.

Grey matter, meanwhile, is responsible for processing and retrieving information; grey matter sends out instructions and processes impulses transmitted by white matter. Grey matter is not fibrous, but composed of nerve cell bodies, which are uninsulated by myelin sheathing. 

Basically, the non-myelinated grey matter processes information and issues instructions, while the myelinated white matter acts as a  communication pathway both within the brain and with the rest of the body.

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