WHERE in the NEPHRON is the amino acid group (NH4) removed from recycled proteins and converted to urea?
As i understand it, urea production in humans occurs primarily in the hepatocytes of the liver, not in the kidney. The urea cycle involves the use of ATP to drive the conversion of amino acid amino groups, free ammonia, and bicarbonate into urea, which then dissolves into the bloodstream. At the kidney, urea is filtered out of blood through the capillaries of the glomeruli as part of the pre-urine. The nephron’s function is then to reabsorb water in order to create a concentrated urine and prevent water loss. I am not aware of the nephron having a significant biotransformative function such as the production of urea. However, the juxtaglomerular apparatus of the kidney does serve some additional functions, such as the secretion of the hormone resin to modulate blood pressure as well as water balance.