The Collecting Duct Determines the Final Urine pH
The rate of acid secretion by the collecting duct determines the final urine pH and the net acid excretion by the kidney. Despite robust acid secretion in the proximal tubule, because of luminal buffering the pH of the tubule fluid is virtually unchanged by this segment.
The segments intervening between the proximal tubule and the connecting segment have minimal acid-secreting ability, and thus the pH of the tubule fluid that reaches the connecting segment is still similar to that of the glomerular filtrate, pH approximately 7.4. However, the normal urine pH of carnivores ranges from 5.5 to 7.5, that of ruminants ranges from 6 to 9, and even greater extremes of pH in response to acidosis and alkalosis are possible. The collecting duct is responsible for this ability to excrete urine with a pH extremely different from that of plasma.
More on the topic The Collecting Duct Determines the Final Urine pH:
-
Veterinarian -