The equilibrium potential of potassium is
A) -90mV.
B) -65mV.
C) -70mV.
D) +30mV.
E) +66mV.

Question

Quizplus · Accepted Answer

The equilibrium potential of potassium (EK) is determined by the concentration gradient of potassium ions across the cell membrane and the electrical potential difference across the membrane. At rest, the concentration of potassium ions is higher inside the cell than outside, resulting in a chemical driving force for potassium ions to leave the cell. However, since potassium ions are positively charged, leaving the cell would also result in a buildup of negative charge inside the cell, creating an electrical driving force for potassium ions to enter the cell. The EK is the membrane potential at which the chemical and electrical forces are equal and opposite, so there is no net movement of potassium ions across the membrane. This occurs at -90mV, making choice A the correct answer.

The Equilibrium Potential of Potassium Is