Potassium

**Definition:** An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.

**Tree numbers:** - D01.268.549.550 - D01.268.557.575 - D01.552.528.652 - D01.552.547.650