hypotonicity

　

WordNet

1. (of a solution) the extent to which a solution has a lower osmotic pressure than some other
2. (of living tissue) lacking normal tone or tension
3. (of a solution) having a lower osmotic pressure than a comparison solution

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/05/23 18:16:32」(JST)

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"Hypotonic" redirects here. For the muscular disease, see Hypotonia.

Effect of different solutions on blood cells

Micrographs of osmotic pressure on red blood cells

Tonicity is a measure of the osmotic pressure gradient (as defined by the water potential of the two solutions) of two solutions separated by a semipermeable membrane. It is commonly used when describing the response of cells immersed in an external solution. Like osmotic pressure, tonicity is influenced only by solutes that cannot cross the membrane, as only these exert an osmotic pressure. Solutes able to freely cross the membrane do not affect tonicity because they will always be in equal concentrations on both sides of the membrane.

There are three classifications of tonicity that one solution can have relative to another. The three are hypertonic, hypotonic, and isotonic.

Hypertonicity

Hypertonic refers to a greater concentration. In biology, a hypertonic solution is one with a higher concentration of solutes on the outside of the cell. When a cell is immersed into a hypertonic solution, the tendency is for water to flow out of the cell in order to balance the concentration of the solutes.

When plant cells are in a hypertonic solution, the flexible cell membrane pulls away from the rigid cell wall, but remains joined to the cell wall at points called plasmodesmata. The cell takes on the appearance of a pincushion, and the plasmodesmata almost cease to function because they become constricted: a condition known as plasmolysis. In plant cells the terms isotonic, hypotonic and hypertonic cannot strictly be used accurately because the pressure exerted by the cell wall significantly affects the osmotic equilibrium point.

Hypotonicity

Hypotonic refers to a lesser concentration. A hypotonic solution has a lower concentration of solutes in its surroundings, so in an attempt to balance concentrations, water will rush into the cell, causing swelling.

Some organisms have evolved intricate methods of circumventing hypotonicity. For example, saltwater is hypertonic to the fish that live in it. They need a large surface area in their gills in contact with seawater for gas exchange, thus they lose water osmotically to the sea from gill cells. They respond to the loss by drinking large amounts of saltwater, and actively excreting the excess salt. This process is called osmoregulation.

A hypertonic solution is used in osmotherapy to treat cerebral hemorrhage.^{[citation needed]}

Isotonicity

An isotonic solution is one in which its effective osmole concentration is the same as the solute concentration of another solution with which it is compared. This occurs, for example, when the concentration of both water and total solute molecules are the same in an external solution as in the cell content. Water molecules diffuse through the plasma membrane in both directions, and as the rate of water diffusion is the same in each direction that cell will neither gain nor lose water.

See also

• Osmolarity
• Osmosis

References

UpToDate Contents

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• 3. 成人における 多発性硬化症の症状のマネージメント symptom management of multiple sclerosis in adults
• 4. 水分バランス異常（低ナトリウム血症および高ナトリウム血症）およびナトリウムバランス異常（循環血液量減少および浮腫）の一般原則 general principles of disorders of water balance hyponatremia and hypernatremia and sodium balance hypovolemia and edema

English Journal

• Esophageal motility in eosinophilic esophagitis.

• Weiss AH1, Iorio N1, Schey R2.
• Revista de gastroenterologia de Mexico.Rev Gastroenterol Mex.2015 Aug 11. pii: S0375-0906(15)00069-5. doi: 10.1016/j.rgmx.2015.05.005. [Epub ahead of print]
• BACKGROUND: Eosinophilic esophagitis (EoE) is characterized by eosinophilic infiltration of the esophagus and is a potential cause of dysphagia and food impaction, most commonly affecting young men. Esophageal manometry findings vary from normal motility to aperistalsis, simultaneous contractions, d
• PMID 26275635

• Hypertonicity contributes to seawater aspiration-induced lung injury: Role of hypoxia-inducible factor 1α.

• Liu Z1, Zhang B, Wang XB, Li Y, Xi RG, Han F, Li WP, Fu L, Li Z, Jin F.
• Experimental lung research.Exp Lung Res.2015 Aug;41(6):301-15. doi: 10.3109/01902148.2015.1030803. Epub 2015 Jul 7.
• Drowning is an important public health problem, but the mechanism of acute lung injury induced by near-drowning is rarely reported. The aim of this study is to investigate the role of hypertonicity and HIF-1α in seawater aspiration-induced lung injury. Diverse solutions were used to study the effec
• PMID 26151308

• Identification and Molecular Mechanisms of the Rapid Tonicity-induced Relocalization of the Aquaporin 4 Channel.

• Kitchen P1, Day RE2, Taylor LH1, Salman MM2, Bill RM3, Conner MT4, Conner AC5.
• The Journal of biological chemistry.J Biol Chem.2015 Jul 3;290(27):16873-81. doi: 10.1074/jbc.M115.646034. Epub 2015 May 26.
• The aquaporin family of integral membrane proteins is composed of channels that mediate cellular water flow. Aquaporin 4 (AQP4) is highly expressed in the glial cells of the central nervous system and facilitates the osmotically driven pathological brain swelling associated with stroke and traumatic
• PMID 26013827

Japanese Journal

• Swelling-activated and arachidonic acid-induced currents are TREK-1 in rat bladder smooth muscle cells

• FUKUSHIMA JOURNAL OF MEDICAL SCIENCE 62(1), 18-26, 2016
• NAID 130005156333

• Swelling-activated and arachidonic acid-induced currents are TREK-1 in rat bladder smooth muscle cells

• FUKUSHIMA JOURNAL OF MEDICAL SCIENCE advpub(0), 2016
• NAID 130005127201

• 1A1-G04 静的ストレッチングによる筋緊張緩和を評価する粘弾性指標の検討(福祉ロボティクス・メカトロニクス(1))

• ロボティクス・メカトロニクス講演会講演概要集 2014, "1A1-G04(1)"-"1A1-G04(3)", 2014-05-24
• NAID 110009966611

Related Links

• Hypotonicity - definition of hypotonicity by The Free Dictionary

Define hypotonicity. hypotonicity synonyms, hypotonicity pronunciation, hypotonicity translation, English dictionary definition of hypotonicity. adj. 1. Having less than normal tone or tension, as of muscles or arteries. 2. Chemistry ...

• Hypotonicity | definition of hypotonicity by Medical dictionary

hy·po·to·nic·i·ty (hī'pō-tō-nis'i-tē), 1. Synonym(s): hypotonia 2. A decreased effective osmotic pressure. hypotonicity ↓ Muscle tone; limp muscles hy·po·to·nic·i·ty (hī'pō-tō-nis'i-tē) 1. Synonym(s): hypotonia. 2. A decreased effective ...

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