Question

A patient came to the hospital after a road traffic accident. He had severe muscle injury, and his serum K+ level was found to be 5.5 mEq/L. What will happen to the resting membrane potential in this patient?

• A. No change
• B. Becomes more negative
• C. Becomes more positive
• D. First becomes more positive then negative

Answer 1

The Correct Option is C

In physiology, the resting membrane potential is primarily determined by the concentration gradients of ions across the membrane and the permeability of the membrane to these ions. Potassium ions (K+) play a crucial role in establishing the resting membrane potential.

The normal range of serum potassium levels is typically between 3.5 and 5.0 mEq/L. An increase in serum potassium level, such as 5.5 mEq/L observed in this patient, indicates hyperkalemia.

Impact on Resting Membrane Potential: The resting membrane potential is usually negative due to the higher permeability of the membrane to K+ ions, which have a higher concentration inside the cell compared to outside. The movement of K+ out of the cell through potassium channels maintains this negative potential.

When extracellular K+ concentration increases, the gradient for K+ moving out of the cell is reduced. This causes less K+ to leave the cell, causing the inside of the cell to be less negative compared to the outside. As a result, the resting membrane potential becomes more positive.

Therefore, in this patient with a serum K+ level of 5.5 mEq/L, the resting membrane potential will become more positive.

The correct answer is: Becomes more positive