Which of the following mechanisms operates in the nephron to maintain pH balance in the body?

Question:Which of the following mechanisms operates in the nephron to maintain pH balance in the body?

1. In tubule cells CO 2 + H 2 O → H 2 CO 3 → H + + HCO 3 − then hydrogen ions are transported into the peritubular capillaries

2. In tubule cells CO 2 + H 2 O → H 2 CO 3 → H + + HCO 3 − then hydrogen ions are secreted into the fi ltrate

3. In tubule cells CO 2 + H 2 O → H 2 CO 3 → H + + HCO 3 − then bicarbonate ions are secreted into the fi ltrate

4.Bicarbonate ions from the tubule cells are secreted into the fi ltrate, then H + + HCO 3 − → H 2 CO 3 → CO 2 + H 2 O

Answer:2