So one of the passages in the nervous system for biology that talks about CSF has a question about role of microglia.

In the answer explanation it also describes the role of oligodendrocytes. It says that myelin sheath reduces leakage by increasing capacitance. I was wondering if this is right because on wikipedia and in the EK bio book it says myelination decrease capacitance of axon?

I’ll try my best to explain your question. when the axon is being myelinated, it’s being ‘insulated’, and the job of an insulator is to inhibit the flow of electrons from one plate to another plate (hence the membranes). This allows the accumulation of electrons on the capacitor, leading to an increased capacitance. So yeah the explanation in Uworld is correct. You might have misinterpreted it.

According to the AAMC sample test in c/p #6, the purpose of myelin is to insulate the nerve which will result in a Decrease in capacitance, Increase in conduction velocity, with a Decrease in conductance.

Myelin will increase the distance of nerve so if we refer to the equation "capacitance= ε*A/distance" we can now see how myelin may decrease capacitance...

Please comment if you have other thoughts/ input on this.

https://www.khanacademy.org/science/health-and-medicine/nervous-system-and-sensory-infor/neuron-membrane-potentials-topic/v/effects-of-axon-diameter-and-myelination

I thought this explained it quite well. Sorry if I'm not allowed to post outside content, but its free to access and a good source to supplement your learning here in UWorld. I didn't see the full question yet in my searches but based on how the question was asked and which portion of the axon it is referring to could change the question of capacitance. but either way. thank you for the info and pointing out that question/answer. I'll keep an eye out for it, and now I'll never forget the content