Library · Physiology
Potassium balance
Make it clearer
Most of the body's potassium sits where you cannot see it: inside the cells. It is the most abundant cation in there, meaning the most plentiful positively charged particle inside the cell.
It does not stay there by chance. It is held in place by the sodium-potassium pump, a membrane protein that moves three sodium ions out and two potassium ions in for every unit of energy it spends. It works against the current, because both ions would tend to move the other way.
On top of that, several systems keep watch over it: the kidneys, the digestive tract and hormones. Insulin and aldosterone drive it into the cells.
Think of a pump running nonstop to fill a tank that leaks. That is why the potassium measured in the blood is not a reliable indication of how much potassium the whole body holds.
In brief
Potassium is a mostly intracellular electrolyte, the most abundant cation inside the cell.
The sodium-potassium pump keeps it there, moving three sodium ions out and two potassium ions in against the gradient for every ATP.
A pump running nonstop to fill a tank that leaks.
The kidneys, the digestive tract and hormones regulate it: insulin and aldosterone drive it into cells.
So the plasma level is not a reliable measure of how much potassium the body holds.
Sources (2)
- National Center for Biotechnology Information, StatPearls PublishingHypokalemia, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Sodium Potassium Pump, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated