This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Excretory System (Kidney, Bladder) Acid-Base Balance, Subject name: Physiology
Which of the following is true regarding urea? 
Select and explain. 
A. Transpoed through aquaporins, B. Re-absorbed in proximal tubule, C. No role in concentration of urine, D. Resorption is independent of ADH
B: Re-absorbed in proximal tubule
Answer: B: Re-absorbed in proximal tubule 
Explanation: Urea Urea transpoed UT1, UT2 {UT- urea transpoer} Urea transpo is under the influence of ADH Contributes to 40 % of interstitial osmolarity Recycled & excreted in a concentrated manner. Urea reabsorption: - Urea is freely filtered 50 % of urea is reabsorbed in the proximal tubule with the reabsorption of water (solvent drag) Its secreted in thin ascending limb of LOH, In the CD, urea is reabsorbed together with water.