Help for question on the nervous system.

[mzthang2260]

This was a question and the answer according to the professor is D.

When a neuron is at rest,

A. an action potential is occurring.

B. voltage-gated Na+ channels are inactivated.

C. voltage-gated K+ channels are open.

D. there are more positive charges outside the cell than inside the cell.

I know why the answer is D, but i thought during resting both VOLTAGE-GATED channels were closed? If NA+ channels are closed does this mean activated? i'm so confused.

[mzthang2260]

Anyone who took A&P 2 yet? Or is taking it now?

[Rob27, BSN, RN]

The gated-channels have three states, open, closed and inactivated. There is a difference in being closed and inactivated.

Edit:

Here is a link to a good Interactive Physiology shockwave that does a really good job about explaining things if you cannot understand it.

http://www.interactivephysiology.com/ip10/nervous1/actpot/topic1.html

Slides 7-9 I think are the ones dealing with the gates. Be sure not to just click next when it loads and you read that slide. Do as it says and click areas of the slide, and keep clicking it and it shows different things.

[microtutor]

If you have "Human Anatomy and Physiology" by Marieb, there's a good summary of this on pp. 400-401 (8th Ed.) If you have another edition it is called "Focus - Action Potential". The graph shows that while the action potential is occuring, either depolarization (Na+ flowing into the cell) is occuring, or repolarization (K+ flowing out of the cell) is occuring. As K+ continues to leave the cell, hyperpolarization occurs. The "resting state" - shown before the action potential and after hyperpolarization shows no ions moving through voltage-gated channels.

I hope that helps you