There are 4 classes of potassium membrane channels

Who would have thought that I owe wikipedia for today's 'Wow!' moment that there are 4 major classes of potassium membrane channels.

Significance?

This is such a wonderful finding because my learning about resting and action membrane potentials makes much more sense. More specifically, I know that two different classes of potassium channels are responsible for the resting and for the action membrane potential, which is something I suspected and now have in writing :)

So the resting membrane potential of a typical neuron is negative (close to -60mV) because the membrane is more permeable to potassium ions at rest via the tandem pore domain potassium channels. Therefore, at rest, the positive potassium ions leave the neurons down the electrochemical gradient making the inside of the neurons more negative.
Of note, if the membrane of the resting neuron was more permeable to sodium ions than to potassium ions, the resting membrane potential would be much more positive (e.g. +40mV) because the positive sodium ions would enter the neuron down their electrochemical gradient.

On the other hand, when an action potential arrives, the membrane becomes relatively more permeable to sodium than to potassium ions via opening of voltage-gated sodium channels. As then the positive sodium ions enter the neurons, making the membrane potential more positive (e.g. +40mV).

When the membrane (action) potential reaches a treshold voltage (e.g. +40mV), the membrane again becomes relatively more permeable to potassium ions and less to sodium ions. Now the voltage-gated potassium channels open and allow the positive potassium ions out of the neuron making the membrane potential more negative again.

In the refractory period the membrane is more permeable to potassium ions and the ion concentrations inside and outside of the cell normalise back to the baseline of the resting membrane potential.

Well, I am stil learning so I suspect the above is still too basic at best and plain wrong at worst.