안녕하세요!

There are a few types of voltage-gated ion channels,

the ones that are important for understanding neuronal function are

1) Voltage-gated sodium channels

2) Voltage-gated potassium channels

3) Voltage-gated calcium channels

They are all named similarly because their mechanism of action is the same :

membrane potential changes (voltage changes) causes modification to protein structure,

which allows specific ions to flow down the concentration gradient.

I think I discussed the structure of these proteins in lecture

but think of a typical ion channel protein,

with a tube like structure, where only one type of ion can pass through the opening in the middle.

Now imagine a boulder placed at the opening of the lumen

that blocks the flow of ions.

This is the normal, or "resting state" of the protein.

When a large enough voltage passes through the membrane

the protein changes shape, where this boulder is moved to the side,

opening the lumen and allowing ions to flow freely once again.

And for a very short time, 

sodium or potassium or calcium, depending on what type of ion channel protein you are talking about,

can move freely down the concentration gradient.

Soon afterwards, the membrane is restored to the resting potential

and the protein returns to its original state, blocking the flow of ions once more.

In regards to what is happening from the dendrites :

the dendrites are picking up chemical signals via neurotransmitters released by the pre-synpatic neurons.

One neuron can receive multiple signals from multiple other neurons.

The sum of all these different signals determines whether an action potential will be triggered or not.

(This process is aptly named "summation")

If a strong enough signal is received by the neuron,

the sodium channels will open, causing an initial depolarization,

ultimately resulting in the action potential that propogates down the axon as we discussed in lecture.

neuron 단원은 어렵지만 한편으론 엄청 흥미로운 단원이기도 해요.

지금처럼 쭉 열공하시고 혹시 또 질문이 생기면 게시판에서 만나요! :D