Veterinary Clinical Biochemistry and Laboratory Diagnosis-II

DEFINITION OF ACIDS AND BASES

Acid and Bases

• Acid is a substance that generates H⁺ in solutions(proton donor). Eg. Sulphuric acid, acetic acid, lactic acid and carbonic acid.
• Base is a substance that accepts H⁺ in solutions (proton acceptor) and are also substances that genetrate OH ^-. Eg. Ammonium hydroxide and sodium carbonate. 

The Animal Body Acids

• Due to metabolism acids are produced continuously and add H⁺ in the body and tend to decrease pH of the body fluids.
• Normal pH of blood is 7.4.
• Most of the volatile acid is produced as CO₂ in cell respiration and is subject to the reaction: CO₂ + H₂O ↔ H ₂ CO₃ ↔ H ⁺ + HCO₃^-
• Nonvolatile acid originates very largely from the metabolic transformation of dietary and intermediates of carbohydrate,fat and protein metabolism.
• The concentration of H⁺ ion is kept in the body under rigorous control and maintained within very narrow range at 35 - 45 nanomols/L of body fluid.
•  H⁺ ions concentration (pH) of body fluids is maintained constant.

Buffer system in body fluids

• Dibasic Phosphate / Monobasic Phosphate pKa = 6.7
• Proteinate/Protein pKa = 5.4 - 9.4
• Hemoglobinate / Hemoglobin pKa = 5.4 - 9.4
• Bicarbonate / Carbonic acid pKa = 6.12

Carbonate buffer is the predominant buffer system in body fluids.