1. Of, relating to, or characterized by having a lower osmotic pressure than a surrounding fluid under comparison.
2. A condition in which the total amount of solutes (both permeable and impermeable) in a solution is lower than that of another solution.
For instance: In kidneys, the tubular fluid is:
– iso-osmotic (to plasma) when it is at the beginning of the loop of henle
– hyperosmotic (to plasma) when it is at the tip of the loop
– hyposmotic (to plasma) when it leaves the loop
Word origin: G. hypo: under, below + osmotic: relating to osmosis.
Related forms: hyposmotically (adverb).
Related phrases: hyposmotic solution.
Alternative forms: hypoosmotic.
Compare: hyperosmotic, iso-osmotic.
See also: tonicity, osmosis, osmotic pressure, diffusion, plasma membrane.