Question

Which ion is most responsible for the resting membrane potential (RMP)?

• A. Potassium (K+)
• B. Calcium (Ca2+)
• C. Sodium (Na+)
• D. Chloride (Cl-)

Hint:

The resting membrane potential (RMP) is primarily maintained by potassium (K+) ions, with the Na+/K+ ATPase pump helping to maintain the ion gradient.

Answer 1

The Correct Option is A

The resting membrane potential (RMP) of a cell is primarily determined by the distribution of ions across the cell membrane and the permeability of the membrane to these ions. The most significant ion in establishing the RMP is potassium (K+). This is because:

1. Concentration Gradient: There is a higher concentration of K+ inside the cell compared to outside. This concentration gradient drives the efflux of K+ out of the cell.
2. Membrane Permeability: The cell membrane is more permeable to K+ than to other ions such as Na+, Ca2+, or Cl-. This is due to the presence of potassium channels that allow K+ to move more freely across the membrane.
3. Electrochemical Gradient: As K+ leaves the cell, it creates a negative charge inside the cell relative to the outside. This electrical gradient opposes the further efflux of K+, stabilizing the RMP.

Therefore, due to these factors, potassium (K+) plays the most significant role in establishing and maintaining the resting membrane potential.

Conclusion: Potassium (K+) is the ion most responsible for the resting membrane potential (RMP).