Renal acid-base balance
Kidneys are net excretors of H+
- Reabsorb bicarbonate HCO3- from the urine (tubular fluid)
- Secrete hydrogen H+ ions into the urine
urinary buffers
- NH3 ammonia
- NH3 diffuses into tubular fluid, and NH4+ transported by Na/H antiporter
- NH4 cannot diffuse through membranes
- 50% of NH4 secreted by proximal tubule and reabsorbed in thick ascending limb
- PO4 phosphate
- amount of new HCO3 entering blood == H+ secreted into tubular lumen
Upregulated by:
- ↑ pCO2
- ↓ ECF volume
