Question

Why is the resting potential of a cell -70mV and not 70mV?

Sorry if this is more of a biology question (or even physics) but could anyone explain this using a diagram?

Thank you in advance!

Answer 1

Resting potential of a cell is potential across the cell membrane in resting condition of cell i.e. when there is no action potential.

Resting membrane potential is negative on the inside (-70mV) compared to the outside.

Inside of the cell remains negative compared to outside because of two reasons:

• Na K ion pump continuously operates across living cell membrane: three sodium ions are pumped out of the cell, in exchange of every two potassium ions that return inside the cell.

So number of positive ions inside the cell is less than the number of positive ions present on the outside.

• In presence of positively charged potassium ions in cytoplasm, the zwitterionic amino acids trapped in cytoplasm behave as negative ions.