Question

The electrical difference in charges across a neuron cell membrane is:

a) Positive on the inside
b) The resting membrane potential
c) Approximately 170 mV
d) None of the above

Answer 1

The resting membrane potential of a neuron is approximately -70 mV, which means the inside of the cell is 70 millivolts more negative than the outside. This potential difference is maintained by the selective permeability of the cell membrane and the activity of sodium-potassium pumps.

Step-by-step explanation:

A neuron at rest is negatively charged: the inside of a cell is approximately 70 millivolts more negative than the outside (-70 mV). This voltage is called the resting membrane potential; it is caused by differences in the concentrations of ions inside and outside the cell and the selective permeability created by ion channels. Sodium-potassium pumps in the membrane produce the different ion concentrations inside and outside of the cell by bringing in two K+ ions and removing three Na+ ions. The actions of this pump are costly: one molecule of ATP is used up for each turn. Up to 50 percent of a neuron's ATP is used in maintaining its membrane resting potential.