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a2 biology the liver

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    • Thread Starter

    can someone please explain how urea is removed from the body?

    i get excess protein results in nh2 removal from amino acids (deamination?)
    to form ammonia which is v toxic and soluble so the liver converts to urea which is less soluble n toxic is excreted (removed by kidneys) but where does keto acids come form?
    and the ornithine cycle?

    ik theres loads of resources but for some reason im not quite grasping the concept here..

    Excess protein enters the liver from the small intestine. The amino acid is oxidised and the -NH2 group from the amino acid and a Hydrogen react together forming ammonia.
    Carrier molecules and enzymes in the liver convert the ammonia and CO2 into urea. Each cycle consumes 2 molecules of ammonia and 1 molecule of carbon dioxide, creating 1 molecule of urea CO(NH2)2 and regenerating a molecule of ornithine for another turn.
    The renal artery carries blood to the kidney, while the renal vein carries blood, now with far lower concentrations of urea and mineral ions, away from the kidney. The urine formed passes down the ureter to the bladder.
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Updated: September 11, 2016
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