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Hyperosmotic adj., Definition: relating to, or characterized by an boosted osmotic pressure. Source: modified by Maria Victoria Gonzaga


Hyperosmotic Definition

The word Hyperosmotic is derived from two Greek words: ‘hyper’, an interpretation “excess” and ‘osmos‘, meaning “thrust” or “push”.

You are watching: How can a solution be hyperosmotic but hypotonic?

So, what does hyperosmotic mean? Hyperosmotic defines a equipment that exerts higher thrust or pushes with a membrane.


To have actually a clear expertise of this definition, we first need to know that a equipment is all set by mixing 2 components, i.e. A solute and also a solvent. Because that example: in one aqueous sugar solution, sugar is the solute and water is the solvent.


Hyperosmotic (biology definition): (1) of, relating to, or characterized by an boosted osmotic push (typically higher than the physiological level); (2) a condition in which the complete amount that solutes (both permeable and also impermeable) in a systems is greater 보다 that of an additional solution. Etymology: indigenous Greek “hypo”, definition “under” or “below” + “osmotic”, relating to osmosis.

The lot of solute in a solution ultimately determines the direction the the motion of the solvent in any system. The is a well-established fact that the distinction in concentration outcomes in the advancement of a concentration gradient the drives the motion of the molecules from a higher concentration towards a lower concentration. When the activity of the solvent (water) molecule occurs as result of a concentration gradient throughout a semi-permeable membrane, then this procedure is known as osmosis.

Thus, a solution containing a higher amount the solute in comparison come a comparable solution is well-known as a hyperosmotic solution. Because that example, seawater is hyperosmotic in comparison to freshwater or tap water. Thus, a cabinet from freshwater when inserted in a maker containing seawater will be exposed come a hyperosmotic environment.

The number of solute molecules per equipment volume or load is well-known as osmolarity. This osmolarity regulates the osmotic press exerted by a solution. This is particularly important because that the biological system inside two options are be separated by a membrane, i beg your pardon is normally semi-permeable in nature. Thus, the motion of molecules in a organic system across a biological membrane might be determined by osmolarity. The activity of molecules across the organic membrane is important for maintaining cellular homeostasis. Therefore, osmolarity theatre a duty in maintaining cellular homeostasis.

The osmolarity of the human being serum is tightly regulated within the range of 285–295 mOsm/kg. The majority of the person body cell have comparable osmolarity and are stated to it is in isotonic. The fluid having greater or reduced osmolarity than the person serum is classified together hypertonic or hypotonic, respectively.

The distinction in osmolarity results in the advancement of osmotic pressure, which at some point results in the generation the osmotic anxiety in a biological system. Osmotic press is the push or thrust applied to the solvent molecules to stop them from relocating through the membrane. At this stage, the is very important to know that tonicity and osmolarity room two various things and should no be thought about synonyms. An isotonic systems is no necessarily isosmotic or evil versa. Similarly, a hyperosmotic systems is no necessarily a hypertonic solution. To recognize this, we need to clearly understand the ide of tonicity.

Tonicity is the residential property of the non-penetrating solutes only and also is constantly dependent ~ above the to compare solution. Thus, for a mammalian cell, one isosmotic sucrose systems will be isotonic but for a plant cell, one isosmotic sucrose solution would be hypotonic. This is due to the fact that sucrose cannot permeate in a mammalian cell because of a lack of transporters in that while sucrose deserve to permeate in a plant cell due to the existence of transporters. Thus, the non-permeability of sucrose in the mammalian cell will an outcome in the isotonicity of isosmotic sucrose equipment in mammalian cells.

In see of this, vital question hence arises. How can a solution be hyperosmotic and also hypotonic?

To know this, it is crucial to save in mind the tonicity is determined only by the non-penetrating solutes. So, if a solution has a reduced concentration of non-penetrating solutes, it would certainly be referred to as hypotonic. A timeless example the a hypotonic solution is a 5% dextrose solution having no non-penetrating solutes. Once a cell is placed in a hyperosmotic but hypotonic solution favor 10% dextran, water motion will occur. Therefore, a solution can be hyperosmotic and also hypotonic.


In biology, once the osmolarity that the extracellular fluid is greater than the intracellular fluid, climate the cell is described as exposed come a hyperosmotic environment and will endure hyperosmotic stress.

A greater osmolarity the the extracellular liquid results in the water flux out of the cabinet that results in the cabinet shrinkage, and eventually dehydration of the cell. (Figure 1).

So, what wake up to a cell in a hyperosmotic solution? Exposure that a cell to a hyperosmotic solution have the right to be highly detrimental to it. Together cells will have actually to deal with water efflux, which at some point results in the disruption of various cellular processes, such together disruption the the synthesis and also repair the DNA, protein translation and its degradation, and the malfunctioning that mitochondria. The hyperosmotic condition results in cell shrinkage and the convolution that the nucleus. The cell shrinkage ultimately induces apoptosis causing cell death.

Conversely when the osmolarity of the extracellular liquid is much less than the intracellular fluid, climate the cabinet is claimed to it is in exposed come a hypoosmotic environment. In such an atmosphere influx that the water /solvent will take place (Figure 1).

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Figure 1: Figurative depiction of the exposure and an answer of a life organism to various osmotic conditions. Source: Maria Victoria Gonzaga the allisonbrookephotography.com.

Physiological meaning of the Hyperosmotic Property

The human being body is extremely adaptive to together changes and in order to do so, the cells undergo osmo-adaptive responses within the cells try to adapt to such eco-friendly changes and restore homeostasis. However, fail to gain back this homeostasis regularly results in a hurt or inflammatory condition in the body.

The imbalance in osmolarity deserve to be detrimental to cells and also biological processes and can result in a diseased state. This homeostasis of osmolarity in the human being body is managed tightly v the kidney in addition to the antidiuretic hormone, arginine vasopressin (AVP) exit from the posterior pituitary. Rise in plasma osmolarity root cause the release of AVP from the pituitary gland. AVP, then, acts on the kidney and increases the membrane permeability the the distal tubule in order to rise the tubular reabsorption that water from the kidney. The kidney regulates the proportion of the solute and water in the urine.

Depending on the body liquid condition, the urine output can have low osmolarity (50 mOsm/L) or high osmolarity (1200-1400 mOsm/L). The short osmolarity urine output occurs when the body has actually an overfill of water and extracellular fluid has low osmolarity. In this condition the pee is hypoosmotic. On the contrary, as soon as the body has actually a deficiency that water and extracellular liquid has high osmolarity, hyperosmotic urine formation occurs. Body fluids having greater osmolarity signals the pituitary to release the AVP, i m sorry thereby boosts the tubular water reabsorption indigenous the kidney. As a result, because of water reabsorption, the amount of water is reduced from the to pee output leading to the development of highly concentrated urine or hyperosmotic urine.

Alteration in the osmolarity has also been uncovered to be linked with the induction of inflammatory processes in the body. High extracellular liquid osmolarity has been found to be linked with diseases like hypernatremia, warm stroke, diabetes, organization burns, dehydration, asthma, cystic fibrosis, and uremia. Pro-inflammatory cytokines such as TNF, IL1β, IL6, IL8, and IL18 have been uncovered to be pertained to hyperosmotic stress-related pathologies.


For instance: In kidneys, the tubular fluid is:

hyperosmotic (to plasma) once it is at the guideline of the loop hypo-osmotic (to plasma) once it leaves the loop

Therapeutic Applications that the Hyperosmotics

Hyperosmotic agents are provided for the therapy of Glaucoma. Glaucoma is an eye or ophthalmic disorder wherein over there is rise in the intraocular push (IOP). Boost in IOP is a extremely painful condition for the patient in addition to poor visualization. Hyperosmotic agents diminish the IOP by generating an osmotic gradient in between the blood and the intraocular fluid compartments which outcomes in the flux that ophthalmic fluid to the blood. This therapeutic method is wanted when the glaucoma is nonresponding to the carbonic anhydrase inhibitors administered topically or even systemically. However, hyperosmotic agents have actually a quick duration that efficacy and likewise induce systemic next effects.

In glaucoma, IOP is elevated as result of vitreous fluid in the eye. On management of hyperosmotic agents, the osmolality of the intravascular fluid increases (hyperosmolarity). However, the ophthalmic obstacle does not enable the permeation of these agents into the vitreous humor. This results in the generation of the osmotic gradient. This, in turn, outcomes in the liquid from vitreous efflux right into the vascular fluid. Consequently, the reduced amount the vitreous humor reduces the IOP in the patient.

Almost a 3-4% reduction in IOP has actually been reported on the administration of the hyperosmotic agents in patients v glaucoma. The efficacy of this agents depends on a number of factors choose molecular weight, dose, concentration, rate of administration, setting of administration, excretion rate, distribution, and also ophthalmic penetration.

Some that the examples of the hyperosmotic offered in glaucoma therapy space glycerin, urea, isosorbide, mannitol, etc. This agents have the right to be given topically, parenterally and orally. However, systemic (parenteral) or oral management of this agents might result in particular side results (Table1).

Table 1: frequently used hyperosmotic agents for treating ocular disease, Glaucoma, and their dose and also potential side effects

Hyperosmotic agentRoute the administrationDose and duration that actionSide effects
Isosorbide Oral 1.5-2.0 g/kg; 3.5-4.5h Nausea, vomiting
Glycerin Oral 1.0-1.5 g/kg; 4-5h Hyperglycemia/glycosuria, high calorie, Nausea, vomiting, headache
Mannitol I.V injection 10%-20% solution; as much as 6h Allergy, Pulmonary edema, heart failure
Urea I.V injection 30% solution; as much as 5-6h Thrombophlebitis, organization necrosis, headache, nausea, vomiting, transient elevation in blood urea nitrogen

Hyperosmotic agents are also used for boosting visualization in patients v corneal edema wherein, hyperosmotic agents cause transient dehydration to relieve the oedematous problem of the cornea. Except corneal edema, hyperosmotic agents are additionally used in the management of cerebral edema. Hyperosmotic agents can additionally be possibly utilized in the therapy of hypovolemic hemorrhage, as a plasma volume expander. A mixture that 7.5% NaCl (sodium chloride) and 6% dextran-70, have been reported to it is in an reliable plasma expander. This ingredient of hyperosmotic agents (NaCl and also dextran) has additionally been reported to considerably reduce mortality due to traumatic hypotension and head injury. The treatment through the hyperosmotic agent has actually been reported to induce quick cardiovascular effects, which include elevation in cardiac parameters favor arterial pressure, cardiac output, the volume that plasma, cardiac contraction, median circulatory systemic pressure, and also oxygen delivery and its consumption.

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Hyperosmotic stress and anxiety in Plants

Not only pets are vulnerable to physiological interruptions due come hyperosmotic anxiety but likewise plants. Hyperosmotic tension in plants is often caused by hyperosmotic problems (when the osmolarity outside is greater than the within of the cell). The common reasons are the high salt concentration that the floor or once there is drought. Once this happens, the plants counter the efflux of water and also the eventual decrease in cabinet volume by a readjust in the hereditary expression, manufacturing of intracellular osmolytes, and energetic endocytosis and also ion sequestration v vacuolar transport. Otherwise, the tree cell could die native loss of turgor pressure and the fallen of the plasma membrane when the too much perturbation is not solved soon.

References:

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