The sodium-potassium pump does not allow the movement of sodium molecules against their concentration gradient into the cell with the use of ATP molecules.
In sodium-potassium pump, the sodium moves outside the cell whereas potassium moves inside the cell with the help of using ATP molecules. The sodium-potassium pump maintains the gradient of higher concentration of sodium extracellularly means outside the cell and a higher level of potassium intracellularly means inside the cell. This process is done only in the presence of ATP molecules that provides a force for the movement of sodium and potassium so we can conclude that no movement of sodium occur inside the cell in the sodium-potassium pump.
