osmoregulation


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osmoregulation

 [oz″mo-reg″u-la´shun]
adjustment of internal osmotic pressure of a simple organism or body cell in relation to that of the surrounding medium. adj., adj osmoreg´ulatory.

osmoregulation

(ŏz′mə-rĕg′yə-lā′shən)
n.
Maintenance of an optimal, constant osmotic pressure in the body of a living organism.

os′mo·reg′u·la·to′ry (-lə-tôr′ē) adj.

osmoregulation

the control of OSMOTIC POTENTIAL or WATER POTENTIAL in organisms. Water molecules tend to move from an area of high osmotic or high water potential (low osmotic pressure) to an area of low osmotic potential or low water potential (highosmotic pressure), when separated by a differentially permeable membrane. Where cells are bathed in a solution, water tends to cross the cell membrane in order to equalize the water potential on either side.

In a dry atmosphere or the marine environment, organisms tend to lose water to their surroundings. In a wet atmosphere or in freshwater, organisms may have difficulty in losing water. Various means are thus adopted to maintain a correct water balance. Xerophytic plants (see XEROPHYTE).may reverse the normal stomatal rhythm, develop a waxy cuticle, fold leaves, store water (succulent plants) or survive dry periods as spores or seeds. Excess water may be removed by GUTTATION in some plants, and by CONTRACTILE VACUOLES in some unicellular organisms. In mammals osmoregulation is carried out by the kidney, water passing out of the blood stream into the kidney tubule via the BOWMAN'S CAPSULE and reabsorbed, where necessary, in the tubule itself. Marine fish, reptiles and birds are able to eliminate salt through special excretory cells. Different groups of animals remove NITROGENOUS WASTE in different ways - all associated with osmoregulation. Many marine organisms have blood that is ISOTONIC with sea water, and so do not have an osmoregulatory problem.

References in periodicals archive ?
Osmoregulation as a selection criterion for drought tolerance in wheat.
Ben-Amotz and Avron (1982) suggested that an alga producing massive amounts of useful organic compounds by osmoregulation make it a natural organism for cultivation.
During October and December 1992 and February 1993 clams, were collected from Fence Lake, located between the Intracoastal Waterway and the Gulf of Mexico in Sea Rim State Park, Jefferson County, Texas and osmoregulation experiments were conducted.
Although it is possible that elderly subjects with abnormalities of osmoregulation and AVP secretion are over-represented in the study group of this research, the apparent high frequency of occurrence them of a deficiency of osmotically stimulated AVP, together with the well documented decrease in thirst perception with age and the difficulty many elderly people may have with the practicalities of toileting, has very important implications for the maintenance of fluid balance and further research in normal elderly subjects is called for.
These include genes associated with osmoregulation, oxygen binding and delivery, and many other aspects of marine life (hereafter referred to as "nonneutral" or "candidate" genes; see Table S1 [available online], Table S2 [available online], and Kosiol et al., 2008).
Alterations in osmoregulation, antioxidant enzymes and indole alkaloid levels in Catharanthus roseus exposed to water deficit.
Osmoregulation and ion homeostasis governing water intake in plants are important mechanisms for coping with drought.
Accumulation of osmoregulation is an efficient mechanism in drought- tolerant plants for maintaining turgidity under water stress conditions.
The prolactin gene (PRL) encodes an essential hormone for initiation and maintenance of lactation, milk protein genes expression, osmoregulation, growth and development, reproduction and immune functions (Zukiewicz et al., 2012).