Sodium & potassium

Mineral Metabolism
1-SODIUM

Sodium is the most abundant cation in the ECF, representing 90% of all extracellular cations, and largely determines the osmolality of the plasma. Na+ concentration in the ECF is much larger than inside the cells.

functions of Sodium

• It is usually associated with chloride and bicarbonate in regulation of acid base equilibrium .
• the preservation of normal irritability of muscles
• permeability of cells and in the maintenance of osmotic pressure of body fluid , thus protecting the body against excessive fluid loss .
• Transmission and conduction of nerve impulses
• Responsible for osmolarity of vascular fluids
• Sodium shifts into cells and potassium shifts out of the cells (sodium pump)
• Sodium ions are essential for muscles contraction

Daily requirement is 1-3.5 gm . About 95 % of the sodium which leaves the body is excreted in the urine as sodium chloride .
. Sodium is readily absorbed so that faces contains very little except in diarrhea . Sodium is present in the blood mainly in the serum . Normal serum sodium level is 133-146m Eq / L.