Question

Which mineral element is present in sufficient strength in extracellular fluid but minimum in intracellular fluid?

• A. $K$
• B. $Na$
• C. $Mg$
• D. $Cl$

Answer 1

The correct option is B $Na$

Ion concentrations in mmol/l
Source	Sodium	Chloride	Potassium	Magnesium
Intracellular fluids	8	150	31	10
Extracellular fluids
Sweat	15-53	4-8	2-5	15-70
Urine	32-224	43-6-	8-10	39-218
Blood plasma	96-110	3-6	1-2	135-145
Saliva	11-45	11-23	0.1-0.4	10-75

A variety of minerals present in the body help to maintain acid-base balance, blood volume, membrane permeability and also form the constituents of bones and teeth. Body fluids are either intracellular (inside cells) or extracellular (blood or tissue fluid). To accomplish their functions body tissues maintain intracellular and extracellular ions in different concentrations. Chloride ion is the most common negative ion along with sodium in the extracellular fluid. Potassium, magnesium and phosphate are most abundant intracellular ions. Sodium and chloride account for 80% of the materials in the extracellular fluid. Sodium chloride helps in maintaining the proper concentration of body fluids, enhances glucose absorption and allows proper conduction of impulses along nerve and muscle tissues. Potassium helps in the synthesis of proteins and speeds up the energy metabolism. Magnesium allows the body's chemical reactions and biochemical pathways to function efficiently. Although the magnesium content is high, about 60% of the body's magnesium exists in the skeleton along with calcium and phosphorus. Sodium is the most plentiful ion in the blood as well as urine. Thus, the correct answer is option B.