Question

Which of the following does NOT determine the Resting Membrane Potential:

• A. Unequal distribution of ions in the Extracellular Fluid (ECF) and cytosol
• B. Inability of most anions to leave the cell
• C. The electrogenic nature of the Na$^{+}$-K$^{+}$ ATPases
• D. Because the plasma membrane has less K$^{+}$ leak channels than Na$^{+}$ leak channels
• E.

Hint:

Resting membrane potential is mainly determined by the Na$^{+}$-K$^{+}$ ATPase pump and the differential permeability of the membrane to K$^{+}$ ions.

Answer 1

The Correct Option is D

Step 1: Resting membrane potential.
The resting membrane potential is established by the differential distribution of ions across the cell membrane. This is primarily driven by the Na$^{+}$-K$^{+}$ ATPase pump, which actively expels sodium and imports potassium.
Step 2: Anions and their movement.
Intracellular anions, such as proteins, are largely confined within the cell. This contributes to the negative intracellular charge, which is crucial for maintaining the resting potential.
Step 3: Electrogenic nature of the Na$^{+}$-K$^{+}$ ATPase.
The Na$^{+}$-K$^{+}$ ATPase pump is electrogenic, meaning it influences the membrane potential by transporting three Na$^{+}$ ions outward for every two K$^{+}$ ions transported inward, resulting in a net negative charge inside the cell.
Step 4: Analyzing the options.
- (A) Unequal distribution of ions: This is a determinant of the resting membrane potential. - (B) Inability of most anions to leave: This is a contributing factor to the resting potential. - (C) Electrogenic nature of Na$^{+}$-K$^{+}$ ATPase: This also contributes to the resting membrane potential. - (D) Less K$^{+}$ leak channels: This does not significantly affect the resting membrane potential, as K$^{+}$ leak channels are generally sufficient for its establishment.
Step 5: Conclusion.
Consequently, the correct answer is (D), as the quantity of K$^{+}$ leak channels does not directly dictate the resting membrane potential.