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Sophrosyne
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- TL;DR Summary
- Why doesn't the saltatory nerve conduction signal diffuse to other adjacent nerve fibers?
Saltatory nerve conduction occurs because of myelination of nerve fibers. This is done by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. From what I understand, it happens because depolarization of the membrane at an unmyelinated area of the fiber (node of Ranvier), causes the potassium concentration to increase in the extracellular environment and sodium concentration to decrease, depolarizing the fiber. This chemical concentration gradient is then transmitted across the myelinated area to the next node, so that the message gets relayed faster and more efficiently. The energy intensive Na+/K+ pump doesn't have to actively work to propogate the signal every step of the way along the fiber.
But looking at a place where there is a whole lot of close and dense intermixing of nerve fibers, like the white matter of the brain, it seems like this would be a recipe for disaster. A concentration change by a Na+/K+ pump at one node could potentially cause a discharge of nerve fibers all around it, creating all sorts of mixed messages.
Am I misunderstanding how this works?
But looking at a place where there is a whole lot of close and dense intermixing of nerve fibers, like the white matter of the brain, it seems like this would be a recipe for disaster. A concentration change by a Na+/K+ pump at one node could potentially cause a discharge of nerve fibers all around it, creating all sorts of mixed messages.
Am I misunderstanding how this works?