# What is the mechanism by which myelination reduces the capacitance of the axon membrane?

There are two mechanisms that have been proposed to me.

1) Layering of Schwann cell membrane with conducting fluid between the layers is analogous to several capacitors in series. Since capacitance in series add by the reciprocal rule (as resistors do in parallel), this reduces the total capacitance.

2) The myelin increases the distance between the 'plates' of the capacitor. For parallel plate capacitors $C = \epsilon A/d$ where d = distance between the plates. Thus increasing the distance reduces the capacitance.

Which of these explanations best applies to myelin, or is it in fact a mixture of both?

• Isn't the 2 events behind reduced capacitance, is depending same mechanism? you adding capacitors at series that means you increase acting distance between 2 most-terminal plates. Isn't that? – Always Confused Nov 1 '16 at 5:38
• Adding more capacitors in series does move the terminal plates on either side further away, but I wasn't sure this applied to the equation involving d because adding another capacitor means the charge stored on each plate is reduced also. – D.J. Lawson Nov 1 '16 at 11:05