This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: DNB 2018, Subject name: Physiology
[{'content': 'Dilution segment in nephrom is: \nSelect and explain. \nA. Ascending LOH, B. Descending LOH, C. Collecting tubule, D. Proximal tubule', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The thick LOH is viually impermeable to H20, but large amounts of Na, Cl & other ions are actively transpoed from the tubule into the medullary interstitium. Thus, fluid in thick ascending loop becomes very dilute and k/a diluting segment of the nephron. Proximal tubules: = 65% of the filtered electrolytes is reabsorbed here, along with water ( osmosis & aquaporin - 1). Descending LOH: Water absorbed AQP - 1 much less permeable to Na & urea; there by increasing the osmolarity.', 'role': 'assistant'}]