Kidneys and adrenal glands
Kidneys depicted with renal calculi, pelvis, and part of the ureter, as well as the adrenal gland (hormone production). The kidney produces primary urine, an ultrafiltrate of the blood. During the passage through the tubular system, substances are secreted or reabsorbed, until the secondary urine is formed. Per minute, 120ml of blood is flitrated (glomerular filtration rate, GFR), producing 180l of primary urine per day, of which only ca. 1,8l of secondary urine is excreted by the kidneys.