Question

Draw a graph showing what would happen to resting membrane potential over time, if the sodium/potassium pump were not functioning. How would this affect a neuron's ability to produce action potentials? What does this imply about the quantity of ions that normally cross the membrane during the course of an action potential?

Answer 1

Na-K pumps are very important to maintain resting membrane potential and also for generating action potential. The nerve membrane is permeable to K ions. But very poorly permeable to Na ions. So, Na ions enter with difficulty where as K ions move very easily. Na ions that enter with difficulty, can't leave the cell at all. Where as K ions that enter can leave easily. So there will be accumulation of Na ions inside and accumulation of K ions out side. K ions leave the cell to compensate for the accumulation of Na inside. So the ion concentrations are getting reversed. Because there are more Na ions inside, K ions are moving out and accumulating out side. This completely disturbs the normal nerve environment needed for the resting potential and action potential generation. If it lasts for a long time, resting potential becomes zero , membrane goes to equilibrium state of ions and action potential also can't be generated.This prevents the nerve impulse generation and flow of information across nerve.

Potential 750 zelo mundial Time (msec)

If the Na-K pump does not work for a long time, membrane potential will be zero.

During action potential, Na ions diffuse in to the cell and K ions move out of the cell. But the concentration is reversed now, So no movement of ions can happen and no action potential is generated