What combination of forces affects the membrane potential in a cell?

The electrochemical gradient is the combination of two driving forces that affect the membrane potential in a cell: the concentration gradient and the electrical gradient. The concentration gradient refers to the difference in the concentration of ions across the cell membrane, while the electrical gradient arises from differences in charge across the membrane. Together, these gradients influence the movement of ions into and out of the cell, ultimately determining the membrane potential.

When considering the electrochemical gradient as a whole, it captures the essence of how both concentration differences and electrical forces guide the movement of charged particles. For example, if a specific ion is more concentrated outside the cell but has a negative charge inside relative to the outside environment, both the concentration gradient (favoring movement into the cell) and the electrical gradient (also generally favoring movement into the cell due to opposite charges) work together to influence how that ion behaves.

In contrast, hydrostatic pressure relates to the physical force exerted by fluid in a confined space, and osmotic pressure concerns the tendency of water to move across a semipermeable membrane. While these factors are important in various physiological contexts, they do not directly determine the membrane potential in the same way that the electrochemical gradient does. Therefore, the electrochemical gradient is the comprehensive