How does the loop of Henle enable the mammalian kidney to produce hypertonic urine?I-The ascending limb of the loop actively extrudes Na+.II-The descending limb interacts with the ascending limb to raise the osmolarity of the extracellular fluid in the renal medulla.III-The concentration is further enhanced by the presence of urea, which draws water out of the collecting ducts by osmosis.

A. II and III
B. just III
C. just I
D. I and II
E. I, II, and III


Answer: E

Biology & Microbiology

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