Question

When monitoring fluids and electrolytes, the nurse recalls that the major cation-regulating intracellular osmolarity is:

1 Sodium
2 Potassium
3 Calcium
4 Calcitonin

Answer 1

The major cation that regulates intracellular osmolarity is potassium. It maintains the resting membrane potential in cells and differs from sodium, which is the primary extracellular cation affecting osmotic pressure.

Step-by-step explanation:

When monitoring fluids and electrolytes in a clinical setting, the major cation-regulating intracellular osmolarity is potassium. Potassium is essential for maintaining the resting membrane potential in neurons and muscle fibers, particularly after membrane depolarization and the formation of action potentials. Unlike sodium, which is the major extracellular cation responsible for half of the osmotic pressure gradient, potassium exerts minimal effects on osmotic pressure and is a critical component of the intracellular fluid. The sodium-potassium pumps in cell membranes work to maintain the potassium concentration gradients between the intracellular fluid (ICF) and extracellular fluid (ECF).