Hyperosmotic Definition

Hyperosmotic can refer to solutions that have increased osmotic pressure, or a greater difference between solutes and solutions between a membrane.

In other instances, hyperosmotic refers to a solution that has more solutes, or components of a solution, than a similar solution.

The term hyperosmotic is derived from the Greek words hyper, which means “excessive,” and osmos, which means “push, thrust, or impulse.”

Examples of Hyperosmotic

Cells Becoming Smaller

Science tells us every living object is made of cells. Solids, liquids, and gasses are essentially made of the same materials, in different concentrations.

Obviously, this means that solid things, like glass, wood, and even humans have a very high concentration of cellular matter. Furthermore, only drastic measures, like cutting, breaking, or burning, can permanently change a solid’s shape, weight, or size.

The characteristics of solid objects seem consistent. However, cells are not solid, despite their ability to make solid objects. Besides their selectively-permeable membranes, human cells, for example, are filled with a viscous liquid called plasma. If this plasma exerts more pressure on the inner wall of the cell than the outer wall of the cell, the cell retains its shape.

Hypothetically, however, placing a human – or, more specifically, a human cell – into a solution with a higher viscosity, or a higher concentration of plasma-like materials, may shrink what was once unshrinkable. This is because the solution is hyperosmotic, in that it has a higher concentration of the plasma-like solute, to human cells.

Because the hyperosmotic exterior plasma solution exerts more pressure on the outside of the cell wall than the cell plasma solution itself can, on the interior cell wall, the cell wall will constrict until the pressures of both the exterior and the interior plasma solutions reach equilibrium, or become equal. In simpler terms, the cell shrinks.

The Dead Sea

Although full of organs, the human body, like cells, is 65% water. However, this water is not necessarily pure H2O. It aids our body’s function, transporting things like waste, nutrients, and even oxygen. It also transports electrolytes, namely, salt.

The salt in our bodies, along with body fat, give us buoyancy, or the ability to float in water. Fat does this because it weighs less than water, and floats above it without much effort. Salt is less reliable, for it requires that the salt within the body be of a lower concentration to the solutes found in exterior water.
This latter reason, that exterior water solutes must be more highly-concentrated than interior solutes to for humans to float, is why we float so easily in the Dead Sea. As the Dead Sea’s salty solute concentration is hyperosmotic to other water sources (including humans), it pushes those other sources away or, more specifically, to its surface.

Oil and Water

Water is a versatile substance. While it provides an ideal environment for mixing solutions, it also contains its own molecules, tiny combinations of hydrogen and oxygen, that interact with other molecules in other substances.

Oil is one of these substances. Liquid oils, like olive oil or vegetable oil, are often made of unsaturated fats, or chains of hydrogen molecules with an incomplete covering of carbon molecules. Solid oils, like butter and animal fat, are made of saturated fats, or chains of hydrogen molecules with a complete covering of carbon molecules. Both chains of hydrogen molecules are called hydrocarbon chains.

The hydrocarbon chains in liquid oils are longer than H2O molecules in water. The size of hydrocarbon chains makes it more difficult for them to interconnect, even though they may never bond with one another. H2O molecules, on the other hand, have a “V” shape, which facilitates their forming their own tessellations.

Because H2O molecules fit together smoothly, they exist in higher concentrations than hydrocarbon chains. Therefore, even without their having a solute, pure water is hyperosmotic to oil and pushes oil to its surface, rather than letting oil sink beneath it.

Related Biology Terms

  • Plasma – The material that makes up the interior of the cell, keeping the nucleus and organelles in place.
  • Viscosity – The degree of internal friction present within a liquid, or the thickness of a liquid.
  • Buoyancy – The ability to float in a substance, usually rated on a spectrum.
  • Concentration – The number of solutes in a solution.


1. We float in the Dead Sea because the water in the Dead Sea is ___________ to human bodies.
A. Hypo-osmotic
B. Somotic
C. Hyperosmotic
D. Salty

Answer to Question #1

2. A solution that is of higher concentration than human cell plasma is said to have a higher __________ than human cell plasma.
A. Viscosity
B. Vitrioloity
C. Osmosis
D. Stenosis

Answer to Question #2

3. You place a sealed glass of pure water into a salty solution. Without considering the weight of the glass, what will happen to the water?
A. The water will sink because it is of a higher concentration than the salty solution.
B. The water will sink because it is of a lower concentration than the salty solution.
C. The water will settle on the surface because it is of a lower concentration of solutes than the salty solution.
D. The water will sink because it is of the same concentration as the salty solution.

Answer to Question #3

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