Question

Suppose Kevin’s pre-op blood work indicates that his extracellular potassium concentration is much higher than usual. This condition is known as hyperkalemia and must be corrected before he can undergo surgery. One of the dangers of hyperkalemia is that it makes neurons and muscle cells more excitable. Why does elevated extracellular potassium have this effect?

Answer 1

Answer:

In order for cells to function as they should, they need to communicate and become active when it is necessary. To do this, there is a very important system that is maintained stable by the tight control of ions, particularly potassium, calcium and sodium, inside and outside the cells. When the equilibrium of these is altered, it will have severe consequences. While calcium is maintained mostly in endoplasmic reticulums, potassium can be found in its most concentration inside cells, while sodium is more concentrated usually outside the cell. From the three ions, potassium plays a vital role as it is mainly responsible for generating the excitability of cells as it passes from inside to the outside of the cell, in a normal, controlled way. Because of potassium´s strong role in the whole action potential, and depolarization, its concentration on the extracellular matrix is always lower than inside the cell.

But in hyperkalemia, the case is not so. In hyperkalemia we have an unusual level of potassium present in the bloodstream, and not in the cell. The result of having this disbalance is that the cell membranes, especially muscle cells like heart muscle, and conduction cells, as well as neurons, are maintained in a constant state of excitation and they become unresponsive to the stimulation of controlling mechanisms. When this happens, organs, and even entire systems, become impaired.