How Does the Renal Countercurrent Multiplier Mechanism Allow the Creation

question 82

Multiple Choice

How does the renal countercurrent multiplier mechanism allow the creation of a concentrated urine?

• A) It transports NaCl from the medullary interstitium into the collecting duct, which directly increases the osmolarity of the urine.
• B) It transports urea from the medullary interstitium into the collecting duct, which directly increases the osmolarity of the urine.
• C) By concentrating NaCl in the renal medullary interstitium, it allows water to be reabsorbed from the collecting ducts when vasopressin is present.
• D) By pumping NaCl and urea into the ascending limb of the loop of Henle, it raises the solute load, which turns into a concentrated urine once water is extracted from the collecting duct.
• E) When anti-diuretic hormone is present, it stimulates the pumping of NaCl from the medullary interstitium and water follows, concentrating the urine.

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