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[?].
Urine contains large amounts of urea, an excellent source of nitrogen for plants. As such it is a useful accelerator for compost.
Although urine is commonly believed to be 'dirty' this is not actually the case. In cases of kidney or urinary tract infection the urine will contain bacteria, but otherwise urine is virtually sterile when it leaves the body. The distinctive smell of urine is not related to the presence of germs.
Some diseases alter the quantity and consistency of the urine, eg. diabetes.
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