This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidneys and Body Fluids, Subject name: Physiology
Concentrating ability of kidney is lost by damage to? 
Select and explain. 
A. Glomerulus, B. Loop of Henle & collecting duct, C. Macula densa, D. Renal Pelvis
B: Loop of Henle & collecting duct
Answer: B: Loop of Henle & collecting duct 
Explanation: Ans. b (Loop of Henle & collecting duct). (Ref. Ganong, Physiology, 21st/pg.721)NEPHRONS# Proximal convoluted tubule-- reabsorbs all of the glucose, inorganic phosphate, Cl, lactate and amino acids and most of the bicarbonate, sodium, and water. Secretes ammonia, which acts as a buffer for secreted W+.QThin descending loop of Henle--passively reabsorbs water via medullary hypertonicity (impermeable to sodium). Thick ascending loop of Henle--actively reabsorbs Na+, Mg2+ and Ca2+, impermeable to H2O, H+: and K+ extrusion occurs.# Glomerulus does the fuction of filtering.# Macula densa secretes renin# Renal pelvis one of the part of PC system that collects urine.