osmoreglering

Osmoregulation, sometimes rendered as osmoreglering in certain languages, is the physiological process by which organisms regulate the balance of water and dissolved substances to maintain cellular and organismal homeostasis. It involves controlling body-fluid osmolarity, ion concentrations, and volume in the face of changing external environments. Organisms may be osmoconformers, whose internal osmolarity tracks the environment, or osmoregulators, which maintain a relatively constant internal osmolarity regardless of surroundings.

In animals, osmoregulatory work is carried out by excretory and circulatory systems. Kidneys filter blood and produce urine, employing transport proteins to move ions such as Na+, Cl−, and K+ and to regulate water reabsorption. Hormones like vasopressin (antidiuretic hormone) and aldosterone adjust kidney function to conserve or excrete water and salts as needed. Fish illustrate contrasting strategies: freshwater species face osmotic water gain and ion loss, producing dilute urine and actively absorbing ions; marine species drink seawater and excrete excess salts via gills and kidneys. Terrestrial animals combine physiological and behavioral strategies to minimize water loss.

In insects, osmoregulation involves Malpighian tubules and excretory glands that secrete and reabsorb ions and water to maintain balance. Plants regulate osmotic balance through accumulation of compatible solutes (such as proline and glycine betaine), regulation of stomatal conductance to control transpiration, and transport of ions across roots and vacuoles.

Osmoregulation is essential for maintaining cell turgor, enzyme function, and overall homeostasis across diverse taxa, particularly under salinity, dehydration, and environmental fluctuation.