Multiple choice

Bicarbonate is maximally absorbed from:

  1. PCT

  2. DCT

  3. Collecting duct

  4. Thick ascending loop of Henle
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The proximal convoluted tubule (PCT) reabsorbs approximately 80-85% of filtered bicarbonate. This occurs via sodium-hydrogen exchangers (NHE-3) that secrete H+ into the lumen, which combines with filtered HCO3- to form H2CO3, then CO2 and H2O. CO2 diffuses back into the cell and is reconverted to HCO3- for reabsorption.

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