Functions of Sodium and Potassium
Function of Sodium
The chemical properties of sodium are similar to that of potassium but the biological functions to penetrate the cell membranes are different due to their different atomic size. The metals also differ in their transport mechanism and efficiency to activate enzymes. Sodium ions are more abundant outside the cells. For example in the blood plasma and in the interstitial fluids surrounding the cells. The sodium and potassium ions participate in transmitting nerve signals and regulate the flow of water molecule across the cell membrane. The transport of sugar and amino acids into the cell is also influenced by sodium ions.
Functions of Potassium
Potassium ions occur at a higher concentration inside the cells. It activates many enzymes and participates in the oxidation of glucose to produce adenosine triphosphate (ATP). It also helps to move nutrients into cells and waste products out of cells. About 98 percent of the potassium in your body is found in your cells. Of this, 80 percent is found in your muscle cells, while the other 20 percent can be found in your bones, liver, and red blood cells.
Sodium Potassium Pump
The steep concentration gradient between sodium and potassium ions across the cell membranes is largely maintained by the Na-K pump. Na-K pump consumes more than one-third of the ATP used by resting animals, approximately 15 kg per day in a resting adult human. The ion pumps work with membrane-bound enzymes which catalyze the movement of sodium-potassium ions in opposite directions. Two potassium ions enter the cell with the expulsion of three sodium ions, the energy is derived from the hydrolysis of ATP catalyzed by magnesium.
