There is a question in my Biology textbook:

"Which blood vessel in the human body carries most impure blood after few hours of meal."

The answer is given as Renal artery.

But I think the answer should be Hepatic Vein, because the liver produces urea and other waste materials and then it pours it all in the right ventricle of the heart for oxygenation. And then the heart distributes the blood to various parts of the body. So the impure blood brought by the Hepatic Vein and other blood vessels gets distributed through the aorta. This will automatically imply that the Renal Artery will contain lesser impure blood than the Hepatic Vein.

Impure blood is the blood with urea, uric acid and other components of urine.

It would be good if you give your opinion and also a reason for it.

  • $\begingroup$ The problem with this question is that "impure" is too non-specific a term. What blood components are impurities? $\endgroup$
    – Alan Boyd
    Jan 20, 2013 at 13:05
  • $\begingroup$ @AlanBoyd Impurities include urea uric acid and other components which are there in urine. $\endgroup$ Jan 20, 2013 at 15:24
  • $\begingroup$ yup toxins from the liver breaking down and concentrating impurities from the blood. in physiology its not as vague as it sounds... $\endgroup$
    – shigeta
    Jan 21, 2013 at 16:58

1 Answer 1


It's the renal artery because it will contain everything from the liver as you describe plus all waste accumulated on the way from the liver to the kidney. Here it gets filtered, so there cannot be a place after the kidney that is less "pure".

  • $\begingroup$ please read the question again and make necessary changes in the answer. I have revised the question in order to include more details. $\endgroup$ Jan 20, 2013 at 15:27
  • $\begingroup$ +1 - "...plus all the waste accumulated on the way from the liver to the kidney." And there's the rub. $\endgroup$
    – MCM
    Jan 20, 2013 at 16:45
  • $\begingroup$ @PranitBauva the changes don't really affect the answer as written $\endgroup$
    – Rory M
    Jan 20, 2013 at 19:26
  • $\begingroup$ But the urea containing blood liver distributed through the body from the heart , as some of the blood goes to the kidney so renal might not contain that much of urea right? As OP has mentioned $\endgroup$
    – Sudhanva
    Mar 31, 2019 at 12:15

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