Hypertonic solution

A solution is hypertonic relative to another when it has greater effective osmotic pressure, drawing water toward it across a semipermeable membrane.

Osmosis: The net movement of solvent across a selectively permeable membrane toward the side with greater effective solute concentration. Water crosses the membrane toward the hypertonic side, producing the defining volume change.
Semipermeable membrane: A barrier that permits some substances to pass while restricting others. Its selective permeability determines which solutes can sustain the hypertonic gradient.
Hypertonic saline: A sodium chloride solution with a higher concentration than physiological saline. Clinicians use it in selected settings to draw water between body-fluid compartments.
Hypotonic solution: A solution with lower effective osmotic pressure than a comparison solution. It drives water in the opposite direction, toward the lower-pressure side.
Osmotic pressure: The pressure required to prevent net solvent flow across a semipermeable membrane. A solution is hypertonic when its effective osmotic pressure exceeds that of its comparator.
Osmolarity: The concentration of osmotically active particles per liter of solution. Osmolarity counts particles, but does not alone establish a lasting effect on cell volume.
Intravenous fluid therapy: The administration of fluids directly into a vein for hydration or treatment. Choosing a hypertonic infusion can alter extracellular and cellular water distribution.
Isotonic solution: A solution with equal effective osmotic pressure to a comparison solution. It causes no sustained net water shift between the compared compartments.
Tonicity: A measure of how a solution changes cell volume through sustained water movement across a membrane. Hypertonicity is one possible relationship described by tonicity.
Osmolality: The concentration of osmotically active particles per kilogram of solvent. Laboratory measurements often report osmolality when comparing body fluids and solutions.

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Hypotonic (osmotic solution)Compared with: It reverses the usual direction of cell-volume change associated with a hypotonic exterior.