3
$\begingroup$

It's always the same explanation that currents are able to "hop" along Ranvier nodes instead of passing continuously along the axon making saltatory conduction more efficient than continuous conduction.

However, if we take this down to the molecular level, I cannot understand how they are different. Conduction in unmyelinated nerve fibers are first triggered by an effective stimulus, changing the cell membrane potential and thus opening the voltage gated sodium channels, causing an explosive influx of sodium ions. The action potential is conducted along the fiber through stimulating sodium channels in nearby regions, causing rapid flow of sodium ions into the cell in membrane immediately near the segment of stimulation and this process repeats as the action potential passes unidirectionally along the axon.

Conduction in myelinated nerve fibers are usually described as hopping along the axon, but on the molecular basis, sodium channels are congregated at the site of Ranvier nodes, large numbers of sodium ions that made its way into the cell swim down the axon in the cytoplasma of the nerve fiber reaching the next ranvier node, changing the membrane potential in that specific site therefore triggering another influx of sodium ions.

So to put the question simply, the mechanism of continuous conduction is triggering voltage gated sodium channels continuously along the way, whereas the mechanism of saltatory conduction is triggering-swimming-triggering-swimming...how does this difference essentially make saltatory conduction faster?

$\endgroup$

marked as duplicate by Amory, jonsca, Mad Scientist Oct 17 '13 at 5:45

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.