Question

In the figure given below the structures associated with human kidneys are marked (X,Y and Z). The relative concentrations of urea in these structure is

A. X is sometimes higher than Y 

B. Y is always higher than Z 

C. Y is always lower than Z 

D. Z is sometimes lower than X

Answer 1

The structures are labeled as: 

X – Renal vein 

Y – Renal artery 

Z - Ureter 

The renal artery (Y) carries oxygenated blood to the kidneys from the heart. This blood contains negligible amounts of waste products (such as urea). On the other hand, the ureters (Z) transport urine from the kidneys to the urinary bladder. The urine contains comparatively high amounts of urea to be excreted out. Thus, the relative concentration of urea in Y is always lower than that in Z.