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 primarily determined by the unequal distribution of ions across the cell membrane.
This is mainly due to the action of the Na$^{+}$-K$^{+}$ ATPase pump, which actively transports sodium out and potassium into the cell.
Step 2: Anions and their movement.
Most anions, such as proteins, cannot easily leave the cell. This contributes to the negative charge inside the cell, which helps maintain the resting potential.
Step 3: Electrogenic nature of the Na$^{+$-K$^{+}$ ATPase.}
The Na$^{+}$-K$^{+}$ ATPase pump is electrogenic, meaning it contributes to the membrane potential by moving three Na$^{+}$ ions out for every two K$^{+}$ ions moved in, creating a net negative charge inside the cell.
Step 4: Analyzing the options.
- (A) Unequal distribution of ions: This does determine the resting membrane potential.
- (B) Inability of most anions to leave: This contributes 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 the leak channels for K$^{+}$ are sufficient for this purpose.
Step 5: Conclusion.
Therefore, the correct answer is (D), as the number of K$^{+}$ leak channels does not directly determine the resting membrane potential.