VLD 421: Veterinary Clinical Biochemistry and Laboratory Diagnosis-II (0+1)

MECHANISMS OF ACID-BASE BALANCE REGULATION

                 The ratio of base / acid proprtions of buffer system depends upon rate/ amount of acid production (H+) . The (H+) has to be eliminated by the body to maintain acid base balance normal.

The mechanisms of acid base balance regulation is

 i. Respiratory Regulation

• By increasing or decreasing rate of respiration to eliminate Co2.
•  Alveolar ventilation provides the oxygen needed for oxidative metabolism and eliminates the CO₂ produced by metabolic processes.
• In the normal subject control mechanisms insure the maintenance of adequate oxygen supplies and keep pCO₂ value in the region of 40+/- 5 mmHg.
• Even a slight elevation of paCO₂ results in immediate stimulation of pulmonary ventilation.
• pO₂ constitutes an effective stimulus to ventilation only when its value drops to less than 70 mmHg.

Renal Regulation

• All variations of body fluid hydrogen ion concentration stimulate the appropriate regulatory processes in the kidneys.
• The main functions of the renal regulation are:
  • Excretion of acid.
  • The retention of extant bicarbonates.
  • The production of new bicarbonates to replace that consumed in the buffering of nonvolatile acids.
• Increase of plasma bicarbonate leads to the production of new bicarbonates by the excretion of protons into urinary buffer systems.
• The protons are eliminated trough the formation of ammonium and the conversion of HPO₄^2- to H₂PO₄^-.
• High hydrogen ion concentration stimulates the secretion of hydrogen ions, leading to an increase of ammonium ion concentration.
• High pCO₂ stimulates the renal reapsorption of bicarbonate while low pCO₂ has the opposite effect.