Please give me an explanation under this statement.

Question

Electrolyte concentrations of the plasma and interstitial fluid are very similar while that of ECF and ICF are very different.

Answer 1

Plasma and Interstitial fluids are both ECF (extracellular fluids), while ICF is intracellular fluid. ECF and ICF have different electrolyte concentrations, but since plasma and interstitial fluids are both ECF, they will have similar electrolyte concentrations.