Veterinary Physiology and Biochemistry
Veterinary Physiology and Biochemistry
This domain tests normal body function and its molecular basis: membrane transport, acid-base balance, electrolytes, rumen fermentation, thermoregulation, endocrinology, enzymes, and intermediary metabolism.
Core rules
- Water and electrolyte balance depends on osmotic and hydrostatic pressures; kidneys regulate sodium, potassium, and water.
- Acid-base: bicarbonate buffer is central; calculate anion gap as (Na+ + K+) minus (Cl- + HCO3-).
- Ruminants obtain energy mainly from volatile fatty acids produced by rumen microbes; glucose is largely made by gluconeogenesis.
- Hormones act by feedback loops; insulin lowers blood glucose, glucagon raises it, parathyroid hormone raises calcium.
- Enzymes are affected by pH, temperature, substrate concentration, and cofactors.
Worked example
A transition cow is recumbent with cold ears and low blood calcium. Reasoning: parturition increases calcium loss into milk, while rumen fill and diet may limit absorption. Low ionised calcium reduces neuromuscular excitability. Parathyroid hormone rises, but bone and kidney responses lag. This is milk fever, not simple hypothermia.
Traps
- Applying monogastric glucose physiology to ruminants.
- Confusing total calcium with ionised calcium.
- Ignoring sample handling that alters blood gases and potassium.
- Assuming all dehydration is isotonic; calf diarrhoea often causes metabolic acidosis.
Exam focus
Use normal values and feedback logic. In calculations, state units and check whether the question asks total, ionised, or bound analyte.