Question

During this step, the pump releases Na+ into the extracellular fluid. Na+ has now been transported from the cytoplasm to the extracellular fluid. Which of the following best describes why Na+ isn’t also transported in the opposite direction—from the extracellular fluid to the cytoplasm?

Answer 1

It is described the Na+/K+ pump and the Na+ does not return to the cell because the channels are closed.

Step-by-step explanation:

During certain stimulus, as the nerve impulse, the Na+ channels are opened and the Na+ enter to the cytoplasm.

In order to recover the membrane potential and the electrochemical balance, the cell use the Na+/K+ pump, wich transport 3 Na+ outside the cell and enter 2 K+, using 1 ATP as energy.