We are taught there is 2 kinds of axons: myelinated and unmyelinated ones but;
Neurocytology and anatomy tell us that the axons are ever covered by myelin compact or not.
Even the geant squi axon is covered by myelin.
Why this fact continues to be ignored?
Does that change the ionic HH model?
Thanks Thomas Fitzgibbon
But you are saying there are exceptions to the rule. I agree.
It seems these exceptions are located clearly near the receptors where the signals/information is transduced to an action potential AP)
"Unmyelinated" fibers are the most common type in peripheral nerves (> 50%). They are surrounded by Remak bundles, a Schawnn cell (see picture).
If this thick layer exists (fact), it is an obstacle to the AP propagation.
Not a single mention of it in traditional descriptionof the propagation.
https://en.wikipedia.org/wiki/Action_potential#Process_in_a_typical_neuron
https://www.ncbi.nlm.nih.gov/books/NBK21668/
How the ionic fluxes are allowed in that case?
You're right Thomas Fitzgibbon
, APs are fortunately propagated but...The ionic theory is based upon a quite invariance of concentrations of the external milieu. If this one is reduced to a very little volume (see picture, external milieu is blue-green), the constant field theory becomes less credible.
In fact, if an electric field exists, it stops any diffusion. The strength of the electric force is ever stronger than any passive/diffusive motion.
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