tonicity

tonicity /to·nic·i·ty/ (to-nis´ĭ-te) the state of tissue tone or tension; in body fluid physiology, the effective osmotic pressure equivalent.

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to·nic·i·ty (t-ns-t)

n.

1. Normal firmness or functional readiness in body tissues or organs.

2. The sustained partial contraction of resting or relaxed muscles.

3. The osmotic pressure or tension of a solution, usually relative to that of blood.

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tonicity

[tōnis′itē]

Etymology: Gk, tonikos, stretching

the quality of possessing tone, or tonus.

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tonicity

the state of tissue tone or tension; in body fluid physiology, the effective osmotic pressure equivalent.

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solution, hypertonic 

A solution with an osmotic pressure greater than that of an isotonic solution. Hypertonic ophthalmic solutions cause some stinging when instilled. Examples: sodium chloride 5%: when applied to an oedematous cornea this solution reduces oedema by drawing water from it; sulfacetamide sodium 30%; glycerol (or glycerin), at a dose of 1-1.5 g/kg body weight given as a solution with water or other liquid, which draws water from the eye into the blood and thereby reduces the intraocular pressure. Syn. hyperosmotic agent. See hyperosmotic agent; osmotic pressure; physiological saline.
hypotonic s. A solution with an osmotic pressure lower than that of an isotonic solution. Hypotonic ophthalmic solutions generally cause less irritation than hypertonic ones. See osmotic pressure.
isotonic s. A solution with an osmotic pressure equal to that on the other side of a semipermeable membrane. Example: sodium chloride 0.9% is considered to be approximately isotonic with the tears. See osmotic pressure; physio-logical saline.