Human urine is usually acidic because

Options

A. the sodium trasporter exchanges one hydrogen ion for each sodium ion in peritubular capillaries
B. excreted plasma proteins are acidic
C. potassium and sodium exchange generates acidity
D. hydrogen ions are actively secreted into the filtrate

Answer

D

Explanation

The proximal tubule is the portion of nephron of the kidney which leads from the Bowman's capsule to the loop of Henle. It regulates the pH of the filtrate by exchanging hydrogen ions in the interstitium for bicarbonate ions in the filtrate. Due to the `H^(+)` ions the human urine is usually acidic. Thus `H^(+)` are actively secrted into the filtrate is the corrent option.