VPB 121: Veterinary Physiology - II (2+1)

METABOLIC ACIDOSIS

• In metabolic acidosis, (ketosis, diabetes mellitus, renal acidosis and diarrhoea) blood HCO₃ falls either as a result of a reaction with acid or due to direct loss from ECF and pH falls. This results in fall of the blood buffer bases.
• Usually no change in plasma PCO₂ because of buffer action can be detected. However, a fall in pH results in increased alveolar ventilation and a fall in PCO₂.
• Decreased PCO₂ will bring the ratio of conjugate base to weak acid back to normal . However, the total bases will be less than normal and this requires renal correction – the excretion of H⁺ and restoration of plasma HCO₃^-.
• The academia stimulates secretion of H⁺ ion by the renal tubule. This ensures reabsorption of all HCO₃ from tubular fluid and the excess H⁺ will begin to acidify the urine. For each H⁺ ion secreted one HCO₃ will be reabsorbed in to plasma.