Question

1. Imagine a cell with a resting membrane potential of -70mV and equilibrium potentials for Na+ of +55mV and K+ of -90mV. When Na+ channels open, how will the membrane potential change and why?

2. Imagine a cell with a resting membrane potential of -70mV and equilibrium potentials for Na+ of +55mV and K+ of -90mV. When K+ channels open, how will the membrane potential change and why?

Answer 1

1. The resting membrane potential of a cell is -70mV means the inside the cell the potential is 70mV less than outside the cell. seems that there is more poaitive charge outside the cell making the membrane potential -ve. As Na+ channels open more Na+ reach the cell and the membrane potential becomes more positive. We know that the equilibrium potential of Na+ is +55mV. So when channel opens this postive charged Na+ moves inside the cell. So the +be charge inside the cell lowers and move more to the positive side.

2. We know that the resting membrane potential is a negative value. More K+ is seen inside the cell. So if the K+ channel open more K+ move outside so the charge inside the cell lowers and the resting membrane potential drops down from -70mV and become more negative.