Question

how and where are hydrogen ions secreted?
multiple choice
passively into the proximal tubule
actively into the entire renal tubule
passively from the distal tubule
actively from the distal tubule

Explanation:

Hydrogen ions are secreted actively from the distal tubule. In the renal system, the secretion of hydrogen ions is an active process (requiring energy, usually in the form of ATP) that mainly occurs in the distal tubule. The proximal tubule is more involved in reabsorption of substances like glucose, amino - acids, and bicarbonate. The entire renal tubule is not the site for hydrogen ion secretion as a whole; it is a more specific region. Secretion is a process that moves substances from the peritubular capillaries (or tubular cells) into the tubular lumen, so the description "from" is incorrect in the context of secretion (it should be "into" if we are talking about the direction of movement from the body's fluids to the tubule lumen).

Answer:

Actively into the entire renal tubule