why is grey matter and white matter in our nervous system reversly arranged in our brain and in spinal cord i want the reason
answer it correctly and fastly i need the correct answer
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Answers
Gray matter are cell bodies, white matter are myelinated fiber tracts.
In the brain, the gray matter is basically the cortex, the white matter lies mainly underneath it. The Cortex is the place where all the higher mental processing takes place.
The white matter in the brain connects the various parts of the cortex so that information can be transported for further processing and integrated.
Since the cortex is the 'processor', it makes sense to connect the parts subcortically (more efficient as it leads to shorter connections). However, the cortex has been expanding very late in evolution, so this 'endpoint reasoning' can be contested, because from an evolutionary perspective, more cortex was needed and hence it was expanded right where it happened to be, namely in the outer part of the brain.
In the spinal chord things are pretty much reversed; grey matter within, white matter around it.The white matter, again, is formed by various tracts (and the grey matter with parts that are processing information.
The white matter in the spinal chord constitutes the various sensory and motor pathways to and from the brain, respectively. The gray matter constitutes basic processing nuclei that form the reflex arches in the spinal chord. These reflex arches process incoming sensory information (e.g. pain) and govern motor output (e.g., pulling the hand away from the fire).
Again, the structure makes sense in terms of efficiency, as the reflex arches combine the sensory and motor tracts to govern reflexes, and therefore processing them from within saves space.