Final answer:
The electrochemical gradient for sodium ions (Na+) tends to drive them into the cell due to both a higher concentration of Na+ outside the cell and the cell's negative internal charge. The sodium-potassium pump maintains this gradient by actively transporting Na+ out and potassium (K+) in, which is essential for many cellular functions.
Step-by-step explanation:
In the context of a cell, an electrical gradient refers to the difference in charge across the plasma membrane with the interior typically being negatively charged in contrast to the extracellular fluid. This gradient, along with the concentration gradient, forms the electrochemical gradient that influences ion movement. For sodium ions (Na+), the electrochemical gradient has both a concentration component, which is higher outside the cell, and an electrical charge component due to the negative charge inside the cell. With a labeled arrow, we indicate that the motion of Na+ ions is driven by the electrochemical gradient into the cell.The electrochemical gradient is maintained by cellular mechanisms such as the sodium-potassium pump, which establishes the differing concentrations of Na+ and potassium (K+) ions across the membrane. The pump moves Na+ out of the cell and K+ in, operating against their respective concentration gradients and contributing to the resting membrane potential.In summary, the electrochemical gradient for Na+ ions tends to drive them into the cell, aiding in processes like active transport across membranes. This gradient is responsible for essential cell functions like neurotransmission, muscle contraction, and maintaining cellular homeostasis.