Kidney function alters blood composition between renal artery and vein

Steps:

• Renal artery carries oxygenated blood from aorta to kidneys for filtration and metabolism.
• Kidneys consume oxygen for cellular respiration, reducing its concentration in renal vein.
• Kidneys filter urea from blood into urine, lowering its concentration in renal vein.
• Thus, both oxygen and urea are higher in renal artery than in renal vein.

Why A is correct:

• Renal artery supplies blood with high oxygen (pre-consumption) and high urea (pre-filtration), per kidney physiology.

Why the others are wrong:

• B: Urea decreases in vein due to filtration, not increases.
• C: Oxygen decreases in vein due to kidney metabolism, not increases.
• D: Both decrease in vein, so artery has higher concentrations.

Final answer: A