Question

HUIUU PUIS Cali) 1. Sodium-potassium pump helps nerve cells establish a voltage across their membranes. Explain how these ions are transported across the membrane and how this contributes to membrane potential. What is the role of ATP in this process?

Answer 1

The resting potential of neuron is -70 mV .This is due to the difference in the concentration of positively and negatively charged ions inside and outside the cell .There are sodium and potassium leak channels in the membrane that allows them to leak according to their concentration gradient. There are more number of potassium leak channels as compared to sodium leak channels . Due to this more positively charged potassium ions leave the cell making the inside of the cell more negative as compared to outside (more chloride ions remain inside) .This is opposite situation to the resting potential state wherein the concentration of negative charge outside the cell is more .

At this state the Sodium potassium pump tries to maintain the resting potential of the cell . It uses ATP energy to transport sodium and potassium ions across the cell membrane . For every three ions of sodium transported outside the cell, it transports 2 potassium ions inside the cell . Thus increasing concentration of potassium ions inside the cell and maintaining resting potential.