Why entry of Na into the cell and exit of K increase when K ions are removed from the surrounding RBC?

Question

when potassium ions are removed from the medium surrounding red blood cells, entry of sodium into the cells and exit of potassium increases dramatically. explain.

Answer 1

1. It's the gradient that matters for the sodium/potassium pump.  That is, you want to have an uneven distribution of the ions so that the tendency toward equilibrium for each ion will drive the pump.

2. The cell must maintain a constant electrochemical gradient.  To counteract the outflow of positive ions (K), the cell must import more positive ions (Na).