Which electrolyte is primarily responsible for maintaining resting membrane potential in cells?

Potassium is primarily responsible for maintaining resting membrane potential in cells. The resting membrane potential is the electrical charge difference across the cell membrane when the cell is at rest, typically ranging from -70 to -90 mV in neurons.

This potential is largely determined by the distribution of potassium ions (K+) inside and outside the cell. At rest, there is a higher concentration of potassium ions inside the cell and a lower concentration outside. The cell membrane is more permeable to potassium than to other ions due to the presence of potassium channels, allowing potassium ions to flow out of the cell. This movement of positively charged potassium ions out of the cell contributes to a negative charge inside the cell relative to the outside.

While sodium, calcium, and chloride ions play significant roles in various cellular processes, including action potentials and signaling, it is the potassium ion that primarily dictates the resting membrane potential due to its concentration gradient and the permeability of the cell membrane. Thus, understanding potassium's role is crucial for grasping how cells maintain their electric potential and engage in physiological processes.