Kidneys perform their osmoregulatory role under the effect of Antidiuretic Hormone, which type of urine is produced in this situation?

  • A. Hypotonic urine with decreased volume
  • B. Hypotonic urine with increased volume
  • C. Hypertonic urine with decreased volume
  • D. Hypertonic urine with increased volume

Explanation

ADH makes the distal tubule and collecting duct permeable to water, so water is reabsorbed into the salty medulla and a small volume of concentrated urine leaves. Concentrated means hypertonic, and reabsorbing water necessarily reduces the volume, so the two halves of the answer must move together. Hypotonic urine of large volume is what appears when ADH is absent, as in diabetes insipidus.

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