Question

The concentrations of sodium and potassium are fairly constant. However, there is a transmembrane potential charge difference that exists across the membrane. How is this possible? The concentrations of sodium and potassium are fairly constant. However, there is a transmembrane potential charge difference that exists across the membrane. How is this possible? The concentrations of sodium and potassium are not equal inside and outside the cell. The cell membrane is impermeable to sodium and potassium. Leak channels allow sodium and potassium to move across the membrane, causing the difference in electric charge. The cell is more negative outside than inside.

Answer 1

The concentrations of sodium and potassium are not equal inside and outside the cell.

Step-by-step explanation:

Sodium and potassium ions are maintained at a constant concentration in cells. However, sodium ions are more concentrated in the extracellular fluid than cytosol. Similarly, potassium ions are more concentrated in the cytosol. The differences in the concentration of Na+ and K+ across the membrane create their concentration gradients and potential charge difference.

For example, a resting neuron has more K+ and maintains a negative interior as compared to the surroundings which have more Na+ and is positive.