Question

In long-distance runners, although dehydration tends to cause hypokalemia (the kidney uses sodium to osmotically resorb water back into the bloodstream, and to do this the kidney resorbs sodium at the expense of potassium), during strenuous exercise the repeated firing of muscle cells and the breakdown of stressed cells can each cause excessive amounts of potassium release into the contracted volume of extracellular fluid, resulting in hyperkalemia. What are two opposing results you could expect on neuromuscular function in this scenario? (Hint: think of potassium and calcium)

Answer 1

Long distance runners: potassium is responsible for muscle contraction, if deficiency of potassium leading to muscle cramps, another aspects calcium is released leading to muscle firing at neuromuscular junction leads to cramps.

In the case of strenous exercise, muscle are in stressed conditions, lead to Hyperpolarisation leads to increase in level of potassium in extracellular fluid cause hyperkalemia. Calicum ion exchange with potassium at muscle end plates leads to no regeneration of action potential.