Question

In the maintenance of the cell resting membrane potential ________.

A) extracellular sodium levels are high
B) cells are more permeable to Na⁺ than K⁺
C) the steady state involves only passive processes in all cells
D) the inside of the cell is positive relative to its outside

Answer 1

Resting membrane potential is the voltage across the cell membrane when a neuron is at rest, primarily maintained by the selective permeability of the cell membrane to potassium (K+) ions. The inside of the cell is negative compared to the outside, with a potential difference of approximately -70 millivolts (-70 mV). The actions of the sodium-potassium pump also contribute to the maintenance of the resting membrane potential.

Step-by-step explanation:

Resting membrane potential is the voltage across the cell membrane when a neuron is at rest. The inside of the cell is negative compared to the outside, with a potential difference of approximately -70 millivolts (-70 mV). This potential is primarily maintained by the selective permeability of the cell membrane to potassium (K+) ions, which diffuse out of the cell more freely than sodium (Na+) ions enter it. As a result, the concentration of K+ is higher inside the cell, while the concentration of Na+ is higher outside the cell.

The actions of the sodium-potassium pump also contribute to the maintenance of the resting membrane potential. This pump actively transports Na+ ions out of the cell and K+ ions into the cell, using cellular energy in the form of ATP. This creates an electrical charge imbalance, with a net negative charge inside the cell. Additionally, chloride (Cl-) ions tend to accumulate outside the cell, further contributing to the negative charge within.