The voltage delivering 1 watt depends on how many amps are present. We use watts to measure power (P), and amps (I) times volts (E) equals watts.
The liver and the production of urea Urea is a nitrogen-containing substance which is produced in the liver, in order to deal with excess amino-acids in the body, which is a natural consequence of the fact that we almost always eat more protein than our body needs to assimilate. The process is called deamination.
Urea is released by the liver into the blood and is carried to the kidneys, where it is filtered out of the blood and released into the urine. Since this is an ongoing process, there is usually a small but stable amount of urea nitrogen in the blood.