Question

What is it that determines the electrical potential of a cell?

How does this potential change?

What does the change of electrical potential determine?

Answer 1

Electrical potential of a cell is its membrane potential and it's ability to conduct a stimuli or action potential. The electrical potential is determined the presence of various ions inside and outside the cell. Na+ ions and K+ ions mainly contribute into it. The resting membrane potential of a cell is a -ve value. It's -95mv I skeletal muscle, -60mV to -70mV in neuron, -60mV in smooth muscle. This means there is more negative charge inside the cell compared that on outside. The Na+ present outside cell makes a positive charge there and the k+ ions are inside the cell.

This resting membrane potential change by the opening of the ion channels. During a stimuli the Na+ channels open and the Na+ ions enter the cell making the potential more positive like wise the k+ leaving out of the cell again makes it positive.

The change of this electic potential shows that the membrane potential has changed and marks the generation of an action potential. This makes the conduction of the signal through a cell.