1. Generation of Acid-Base 1)Sources of acid 1 volatile acid CO2+H20>H2CO3>H++HCO3 (H 15 mol /d) 2) fixed acid(non-volatile acid hosphoric sulfuric, lactic, ketone bodies etc H+0.05-0.10mol/d1. Generation of Acid-Base (1) Sources of acid 1）volatile acid CO2 + H2O → H2CO3 → H+ + HCO3 - (H+ 15 mol /d) 2）fixed acid (non-volatile acid) phosphoric, sulfuric, lactic, ketone bodies etc. H+ 0.05 – 0.10 mol /d