(D Renal regulation of acid-base balance Renal compensation begins from several hours after the addition of acid load. and it may take 3-5 days to reach the maximum of this compensatory capacity Kidneys play a major role in the regulation of ph in the body
(III) Renal regulation of acid-base Balance Renal compensation begins from several hours after the addition of acid load, and it may take 3~5 days to reach the maximum of this compensatory capacity. Kidneys play a major role in the regulation of pH in the body
Excrete the nonvolatile acid, reabsorb the bicarbonate,“排酸保碱” keep [Hco3]-maintain acid-base balance HCO3 filtrate through glomerulus freely (5000 mmol/d) 8590-90% is reabsorbed by proximal tubule, others are reabsorbed by distal convoluted tubule and collecting duct 0. 1% is excreted-urine pH 6.0 urine ph vary from 4.4 to 8.0
Excrete the nonvolatile acid， reabsorb the bicarbonate ， “排酸保碱” →keep [HCO3 - ]→maintain acid-base balance。 HCO3 - filtrate through glomerulus freely（5000 mmol/d）， 85%~90% is reabsorbed by proximal tubule，others are reabsorbed by distal convoluted tubule and collecting duct， 0.1% is excreted→urine pH 6.0。 urine pH vary from 4.4 to 8.0
1.in proximal tubule (a* exchange Renal Tubular ecB Tubular interstitial cells aims lumen fluid Na+ Hco Nat K HCO3 +H H H2cO3 H2co Carbonic H o anhydrase coz……-}-…c02+hH2O
1.in proximal tubule (a) Na+ -H+ exchange
2.in distal tubule collecting duct HP〔 HPO: NHi- 一NH a-intercalated cell: secrete H H 管腔 upper membrane CO: CA H-O (a)HATPase HCO ATP 闰细胞 (b)H+-K* ATPase Urinary acidification (H POA THAT UGM-wwnagV/Mv2// 血液 base membrane 图75集合管a闰细胞沙氢保碱示意图 Cl/HCO2 exchange Lumen Blood HCO A H20 +Co K
2.in distal tubule & collecting duct α-intercalated cell: secrete H+ upper membrane: (a) H+ -ATPase; (b) H+ -K+ ATPase Urinary acidification （H2PO4 - ↑NH4 + ↑） base membrane: Cl- /HCO3 - exchange
3. secretion of NH3/NH4+ in proximal tubule 肾小管腔 近曲小管上皮细胞 血液 Na 谷氨酰胺 NH4 H H 氨酸 a酬皮二酸 NH H' HCO HCO, N 管腔膜 基侧膜 图7-3近曲小管泌N重吸收HCO示意图 O表示主动转运●表示继发性主动转运GT表示谷氨酰胺酶
3. secretion of NH3/NH4+ in proximal tubule