sodium
Meaning of sodium: Sodium is an essential electrolyte that regulates fluid balance, nerve signaling, and blood pressure, distinct from table salt itself.
Definition of sodium
Sodium is a mineral and essential electrolyte found throughout the body, playing a central role in maintaining the balance of fluid inside and outside cells, supporting normal nerve and muscle signaling, and contributing to the regulation of blood pressure. It is the main positively charged particle found in the fluid surrounding cells.
Sodium is obtained through the diet, most commonly as part of table salt, a compound of sodium and chloride, meaning sodium makes up only part of salt's total weight rather than being identical to salt itself. Many processed foods contain substantial amounts of added sodium beyond what is added during cooking.
Blood sodium levels are regulated by the kidneys under the influence of several hormones, and abnormal sodium levels, whether too high or too low, can affect fluid balance throughout the body and, in more pronounced cases, brain function, since brain cells are particularly sensitive to shifts in fluid balance driven by sodium concentration.
Used in a sentence
A blood test showed a low sodium level in the patient with persistent vomiting.
Good to know
Sodium and table salt are often used interchangeably in everyday conversation, though salt is a compound of sodium and chloride, so sodium accounts for only part of salt's weight.
Word origin
Where “sodium” comes from
The element symbol Na comes from natrium, a Latin name derived from natron, a naturally occurring mineral form of sodium compounds known and used since antiquity.