Choose between the two options to answer the question specified in the brackets for the following: Example: Corolla or Calyx (Which is the outer whorl?) Answer: Calyx
Blood in the renal artery or renal vein (Which one has more urea?)
Topic: Urea in the renal artery
Answer
The RENAL ARTERY.
The renal ARTERY brings blood TO the kidney to be filtered; the renal VEIN carries it AWAY after filtering. So the blood entering still holds its urea, and the blood leaving has had most of it removed.
THE GENERAL PRINCIPLE, which answers every question of this shape: blood ENTERING an organ carries what that organ will act upon; blood LEAVING carries the result.
Apply it elsewhere and several answers follow at once: blood in the PULMONARY ARTERY has more carbon dioxide than in the pulmonary vein; blood in the HEPATIC PORTAL VEIN has more glucose after a meal than blood leaving the liver.