"Hypertonic" urine - confused

Hi,

When my physiology lecturer taught us about the renal system, he mentioned "hypertonic urine" and said that hypertonic refers to high pressure urine (with hypotonic referring to low pressure). He said that hypertonic urine meant a high volume being excreted in a time period.

However someone else just told me that hypertonic refers to urine concentration (as "tonic" apparently means "salt")

Google gave me a definition about "osmotic pressure" which makes me think that it might be to do with concentration.

Could someone please give me the actual definition of "hypertonic urine"?

Thank you :)

It's the second explanation, the one referring to the number of dissolved molecules.

Dissolved foreign molecules give water a certain 'osmotic pressure,' that is to say a certain behaviour if two different water solutions are separated by a half-permeable membrane. You could say that the dissolved molecules have an attractive or a grabbing effect on the small water molecules around them.

Hyper- is just a medical jargon prefix for "more" or "greater," Iso- as a prefix means "just the same," and Hypo- as a prefix means "less" or "smaller." Hence hypertension = high blood pressure, and hypotension = low blood pressure.

You can use these prefixes to create perfectly valid nonsense words, - for example, hyper-endowed = having a really big willy; hypo-endowed = having a really small willy. Hyper-financed = having lots of money, hypo- financed = having too little money, etc.

Isotonic means "having the same number of molecules dissolved per unit water volume, as blood plasma does." Hypertonic means "having more molecules dissolved per unit water volume, than blood plasma does," and hypotonic means "having fewer molecules dissolved per unit water volume, than blood plasma does."