Urine is liquid waste excreted by the kidneys. The urine collects in the bladder for elimination at a convenient time. The latter is called urination, which means expelling the urine from the body through the urethra. In addition to the excretory function urine serves for the homeostasis of the body liquids and -- in many species -- for olfactory communication.
Urine is the primary method for excreting chemicals and drugs from the body. These chemicals can be detected and analysed by urinalysis.
Although urine is commonly believed to be 'dirty' this is not actually the case. In cases of kidney or urinary tract infection (UTI) the urine will contain bacteria, but otherwise urine is virtually sterile when it leaves the body. The distinctive smell of urine is due to ammonium, and not related to the presence of germs.
Some diseases alter the quantity and consistency of the urine, (e.g. sugar in the urine is a sign of diabetes). Urine therapy is the use of urine topically or consumed, especially as recommended by the traditional Indian medicine, Ayurveda, under the name Amaroli.
Urine is a major excretory product of animals, made up of a watery solution of metabolic wastes and other substances. The fluid collects generally from the blood or interstitial fluid. The composition of urine is adjusted by returning the necessary substances to the body fluid and the excretory product that contains excess or potentially toxic substances is released from the body. Urine flows through the following structures: the kidney, ureter, urinary bladder, and finally the urethra. Urine is produced by a process of filtration, reabsorption, and tubular secretion.
In Siberia, to communicate with the spirits, the indigenous people drank the urine of another who has consumed fly agaric (a hallucinogenic mushroom), or of one who has in turn drunk urine of like source. The potency of the mushroom does not decrease significantly until around the seventh drinker, because the muscimol from fly agaric is essentially unaltered after being secreted from the kidneys. Not only does this conserve the mushrooms, but it also eliminate unpleasant side-effects caused by muscarine, which does not pass on through urine. Likewise, reindeers licked the ground where there is urine containing fly agaric from the religious ritual.
During World War I, soldiers without gas masks urinated on cloth and wore the cloth during a gas attack.
- Urolagnia, an attraction to urine