Sodium is a major element in the human body. It is mainly used as an electrolyte by the body in the extracellular fluid and in the sodium-potassium pump. Sodium ions are the major cation electrolytes within the extracellular fluid that surrounds every cell in the body. These ions in the extracellular fluid are important for regulating the pH and electrolyte concentration of the body. Through the sodium potassium pump, sodium is also necessary for every nerve function in the body. This makes sodium an especially important ion for muscle movement and mental cognition.