physiology q - raheem

[ArchivalUser]

Which one of the following statements is true about the proximal tubule.
A. the Na+/K+ ATPase drives sodium into the cell from the urine side of the tubule
B. Na+/H+ exchange is largely the mechanism by which hydrogen ion secretion occurs
C. bicarbonate reabsorption is independent of carbonic anhydrase activity
D. the pH in the lumen of the proximal tubule can reach as low as about 5.0

[ArchivalUser]

Not the first three choices

i'll pick "D"

pH does drop in order to reclaim HCO3 but i'm not sure if it can drop upto 5.

[ArchivalUser]

THE ANSWERS,,,B,,,,, my best regards

[ArchivalUser]

can u please explain....as far as i know ,Collecting Tubules is the primary site for H ion excretion.

[ArchivalUser]

??????

[ArchivalUser]

@sarim: the renal secretion of H in the form of NH4 (which occurs in the PCT) is quantitatively more important than the secretion of H as a titratable acid (which occurs in the DCT)..

[ArchivalUser]

booo! got confused here!! dont think that my previous post is accurately related to choice B!!