Answer:
Within the extracellular fluid, the major cation is sodium and the major anion is chloride.
Chloride is a major contributor to the osmotic pressure gradient between the ICF and ECF, and plays an important role in maintaining proper hydration. It functions to balance cations in the ECF, maintaining the electrical neutrality of this fluid.
Chloride is by large the major anion in the extracellular fluid.
Its concentration in blood plasma is around 98.00–107.00 (mM), in cerebrospinal fluid (CSF) around 118.00–132.00 (mM) and in urine around 110.00–250.00 (mM); while the concentrations of bicarbonate (HCO3-), the second most abundant anion in blood is 22.00–29.00 (mM).
Chloride is the predominant extracellular anion. Chloride is a major contributor to the osmotic pressure gradient between the ICF and ECF, and plays an important role in maintaining proper hydration. Chloride functions to balance cations in the ECF, maintaining the electrical neutrality of this fluid.
*ICF = intracellular fluid
ECF = extracellular fluid
