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Physiology

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Kidney

Question
5 out of 19
 

In the presence of vasopressin the greatest fraction of filtrated water is re-absorbed in which part of the nephron?



A Proximal tubule
B Distal tubule

C Loop of Henle
D Collecting duct

Ans. A Proximal tubule
  1. Maximum water is reabsorbed in proximal tubule (60-70%) only 10-12 % is absorbed in CD under ADH called facultative water reabsoption.
  2. Vasopressin or Antidiuretic hormone (ADH) increases the permeability of the collecting ducts of the kidney so that water enters the hypertonic interstitium of the renal pyramids, the urine becomes concentrated and its volume decreases. The mechanism by which the vasopressin exerts its antidiuretic effect is activated by V2 receptors leading to insertion of water channels called aquaporins (main is aquaporin 2) in luminal membrane.

Kidney Flashcard List

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