Question

All of the following comparisons between the distal nephron and the proximal tubule are correct except

• A. The distal nephron is less permeable to hydrogen ion than the proximal tubule.
• B. The distal nephron is more responsive to aldosterone than the proximal tubule.
• C. The distal nephron has a more negative intraluminal potential than does the proximal tubule.
• D. The distal nephron secretes more hydrogen ion than does the proximal tubule.

Answer 1

The correct option is D The distal nephron secretes more hydrogen ion than does the proximal tubule.

Secretion of hydrogen in its free, ionized form (H⁺) occurs in the distal tubule and collecting ducts. As mentioned, secretion of H⁺occurs in conjunction with a novel generation of bicarbonate which is subsequently added to the extracellular fluid. Interestingly, tubular secretion of free H⁺can be stimulated by the presence of aldosterone.

So, the correct answer 'The distal nephron secretes more hydrogen ion than does the proximal tubule'