Anyone interested to share your knowledge on myelin and capacitance?

This reply is months late, but I have just joined UWorld. So, if you're still following this post, here is my knowledge:

Myelin acts as an insulator for neuronal conductance. What does that mean? It means it keeps charged species localized around the length of an axon so that the ion gradients are maintained when an electric impulse is propagated. Basically, capacitance is when the neuron is "charged", meaning the positive and negative ions line up on the intra and extracellullar sides of the neuron (inside is negative, outside is positive). Capacitance in a neuron means that there is a positive and a negative side. With the Na/K pump, the ion gradient is created, throwing the equilibrium of the charges off, causing a depolarization and Na+ to rush into the cell, where there is significantly less + charged species.