I was reading a bit of neruo text in a book and it said: The reason why there is a gradient change on the inside and outside of the membrane is because the sodium ions have a stronger positive charge when compared with potassium ions. Please Register or Log in to view the hidden image! THAT is not true. Right? I mean, wtf?!
They probably mean that there are far more Sodium ions then Potassium ions on the outside of the membrane. The insides of cells contain large molecules that are negatively charged and can't cross the membrane. Ionpumps actively pump out Sodium ions to the outside. So there are more Sodium ions going out then there are Potassium ions coming in. There are more Sodium ions on the outside and more Potassium ions on the inside, and the inside has a net negative charge. This creates the gradient. Edit: Shouldn't this be in Biology ? Please Register or Log in to view the hidden image!
I think Enmos has nailed it. What the function of the Na-K-ATPase? To maintain the resting potential across the membrane. It pumps out 3 Na for every 2 K that enters into the cell.
Well, sodium does have a higher charge density than potassium, since they both have the same charge but sodium is smaller. Sounds like you already figured it out though.
Beat me to it again. Although let's not forget about effective nuclear charge. It's a small effect, but it's still present, and still has a measurable impact.