1. Write on the renal regulation on body pH (10 marks)
Renal :
-Long term regulator of acid-base balance
-Slower to respond, may take hours or days to correct pH
-Maintain balance by excreting or conserving HCO3- and H+ ions
-Normal HCO3 level: 22 to 26 mEq/L
2. Renal response to acidosis
• increased HCO3 production which crosses the basolateral membrane
and enters the circulation (plasma [HCO3] increases)
• increased Na+ reabsorption in exchange for H+ and less in exchange
for Cl- (plasma [Cl-] falls)
• increased 'NH3' production to 'buffer' the H+ in the tubular lumen
(urinary excretion of NH4Cl increases)
3. Fate of H+ secretion
• Apical Na+-H+-antiport – bring Na+ into epithelial cells, move out H+
into lumen
• Basolateral Na+-HCO3
- symport – moves Na+ & HCO3
- out of epithelial
cells into interstitial fluid
• H+-K+-ATPase – excrete H+ into urine in exchanged for reabsorbed K+
![Renal response to acidosis
• increased HCO3 production which crosses the basolateral membrane
and enters the circulation (plasma [HCO3] increases)
• increased Na+ reabsorption in exchange for H+ and less in exchange
for Cl- (plasma [Cl-] falls)
• increased 'NH3' production to 'buffer' the H+ in the tubular lumen
(urinary excretion of NH4Cl increases)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)