A particle that carries an electrical charge; positive ions are called cations and negative ions are called anions. Many vital body processes, such as the transmission of nerve impulses, depend on the movement of ions across cell membranes. Sodium is the principal cation in the fluid that bathes all cells (extracellular fluid). It affects the flow of water into and out of cells (see osmosis), thereby influencing the concentration of body fluids.
The acidity of blood and other body fluids depends on the level of hydrogen cations, which are produced by metabolic processes. To prevent the fluids from becoming too acidic, hydrogen cations are neutralized by bicarbonate
anions in the extracellular fluid and blood, and by phosphate anions inside cells (see acid–base balance).
n. an atom or group of atoms that has lost one or more electrons, making it electrically charged and therefore more chemically active. See anion; cation; electrolyte; ionization.
(Greek) Of the sea and islands Ionya, Ionija, Ioniah, Ionea, Ionessa, Ioneah, Ioniya... ionia
n. the process of producing *ions. Some molecules ionize in solution (see electrolyte). Ions can also be produced when ionizing radiation dislodges one or more electrons from an atom or molecule. This can be harmful to DNA in cells, resulting in tumours or genetic defects.... ionization
n. the technique of introducing through the skin, by means of an electric current, charged particles of a drug, so that it reaches a deep site. The method has been used to transfer salicylate ions through the skin in the treatment of deep rheumatic pain. See also cataphoresis.... iontophoresis
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