Blood is brought to the kidney in the renal artery. The kidneys filter the blood and then reabsorb useful materials such as glucose. After it has been purified, the blood returns to the circulation through the renal vein.
Note that ‘ureter’ differs from the word ‘urethra’. The ureters are tubes that carry urine from the kidneys to the bladder, whereas the urethra is the tube that carries urine out of the body.
Urine contains water, urea and salts. Urea is produced in the liver when excess amino acids are broken down. It is the main waste product removed in the urine.