Question

The resting membrane potential of all cells is negative. Assuming that K+ is the main ion that determines the resting membrane potential, which is higher the intracellular K+ concentration or the extracellular K+ concentration?

The extracellular K+ concentration is greater than the intracellular K+ concentration.

The intracellular K+ concentration is greater than the extracellular K+ concentration.

Answer 1

The intracellular K+ concentration is higher than the extracellular K+ concentration, contributing to the negative resting membrane potential of cells due to the action of the sodium-potassium pump and potassium leakage channels.

Step-by-step explanation:

The intracellular K+ concentration is greater than the extracellular K+ concentration. This exists due to the activity of the sodium-potassium pump, which actively transports three sodium ions out of the cell for every two potassium ions it brings in. This pump, along with potassium leakage channels and the relative impermeability of the cell membrane to sodium ions, establishes and maintains the negative resting membrane potential.

While the sodium-potassium pump does contribute to creating a concentration gradient and a net negative charge inside the cell, the leakage of potassium ions out of the cell is a more direct cause of the negative resting membrane potential. The resting potential is approximately -70 millivolts, indicating that the inside of a neuron is negatively charged relative to the outside.