Question

RMP predominantly affected by which ion?

• A. K+
• B. Ca
• C. Na
• D. Cl

Hint:

Potassium ions (K+) are crucial in establishing the resting membrane potential because their movement across the membrane contributes to the negative charge inside the cell.

Answer 1

The Correct Option is A

The resting membrane potential (RMP) refers to the electrical potential difference across the cell membrane during a non-excited state. It is largely determined by the concentration gradients of ions across the membrane and the membrane's differential permeability to these ions. Predominantly, the RMP is affected by the following four ions: potassium (K⁺), sodium (Na⁺), calcium (Ca²⁺), and chloride (Cl⁻).

Among these, potassium ions (K⁺) play the most crucial role in influencing RMP due to the cell membrane being more permeable to K⁺ ions. This is because:

• The cell membrane has a higher concentration of K⁺ leak channels compared to other ion channels, allowing K⁺ ions to move more freely in and out of the cell.
• The concentration of K⁺ is higher inside the cell compared to the outside, leading to its diffusion out of the cell, driven by the concentration gradient.
• This diffusion of K⁺ outwards (due to the concentration gradient) and the attraction back in (due to the electrical gradient created by negatively charged intracellular proteins) establishes a negative charge inside the cell relative to the outside, thus determining the RMP.

Therefore, potassium ions (K⁺) are the primary ion affecting the resting membrane potential.