Final answer:
The electrochemical gradient for Na+ with an equilibrium potential of +60 mV and a membrane potential of -70mV is directed into the cell due to the combined effects of the strong concentration gradient and the electrical gradient.
Step-by-step explanation:
Assuming that for Na+ (higher concentration outside cell), ENa+ = +60 mV and Vm is -70mV, the electrochemical gradient is directed into the cell.
This is because the concentration gradient for Na+ is strong and tends to drive Na+ into the cell, where cells have a higher concentration of potassium (K+) and a lower concentration of sodium (Na+) compared to the extracellular fluid. Additionally, the electrical gradient causes the positively charged Na+ ions to move toward the negatively charged interior of the cell.
The combination of these two forces, known as the electrochemical gradient, influences ion movement across the plasma membrane. As Na+ enters the cell, the voltage will shift toward a less negative value, leading to depolarization.