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 one of the substances in urine, and urine is in your blood stream until the kidney extract the urine from your blood.