hyperton

Hyperton is a term used in physiology and related fields to describe a solution or environment that has a higher effective osmolarity or tonicity than a reference solution. In osmosis, water moves across a semipermeable membrane from areas of lower solute concentration to areas of higher solute concentration; therefore a hypertonic solution draws water out of adjacent cells, causing them to shrink. In plant cells this can lead to plasmolysis; in animal cells it typically results in crenation.

Etymology: from Greek hyper-, above, and tonos, tension.

Usage: The preferred modern term is hypertonic when describing a solution relative to another. Hyperton refers to the object or solution having higher tonicity.

Applications and examples: Hypertonic saline solutions (such as 3% NaCl) are used clinically to treat certain conditions, including hyponatremia and cerebral edema, by creating an osmotic gradient that extracts water from swollen tissues. Rapid or excessive osmotic shifts can be dangerous and must be managed carefully. In nature, hypertonic environments refer to places with higher solute concentration than the intracellular milieu; many microorganisms fail to survive in hypertonic conditions, whereas halophilic organisms require high salinity.

See also: isotonic, hypotonic, tonicity, osmosis, osmolarity.