Re: Myelin like a wound capacitor.
Yes, the membrane does have substantial capacitance and the myelin
sheath has an exceptionally large surface area, providing potentially
an enormous capacitance per unit length along the axon.
However, a real capacitor made of wound foil has a very highly
conducting metal layer connecting the pieces, whereas the sheath
has a very high resistance thin layer of electolyte connecting the
concentric layers. In essence, these layers are capacitors in series,
making the total capacitance very small, not very large. Since
the membrane also has an extremely low conductance (and also consists
of many layers in series) the result IS a very effective insulator.
Of course all this is in all classical intro neurobiology texts, but
then the main expositors on this thread do not believe in the
The main point has already been raised -- show me some experimental
evidence where classical ideas have gone astray. There are already
enough "non-traditional" mechanisms in neurobiology -- cells without
action potentials, bidirectional synapses, NO as a transmitter. I am
quite sure the neurobiology community can handle some more without
falling apart. As long as there is an experimental basis!