Hormones & Energy Metabolism Flashcards
• How do hormones respond to negative energy balance?
Increase – glucagon, GH, cortisol, catecholamines
Decrease – insulin, thyroxine
• What is the main glucose source for ruminants?
Propionate (a VFA)
• What do glucogenic (propionate) & ketogenic (acetate & butyrate) mean?
Glucogenic – converted to oxaloacetate, converted to glucose
Ketogenic – converted to acetyl CoA, produces ATP through TCA cycle, converted into fats, converted into ketones
• What is the function of hormone-sensitive lipase?
Hydrolyses triglycerides to yield glycerol & fatty acids
• What concurrent diseases may be evident in cows suffering from hepatic lipidosis?
Dystocia, left displaced abomasum, retained placenta, metritis, mastitis
• What periparturient events predispose animals to energy metabolism disorders?
Negative energy metabolism in late pregnancy & shift in blood hormones at parturition
• What inhibits HSL?
High insulin & low glucagon
• What must acetyl CoA do to enter the TCA cycle?
React with oxaloacetate
• What are levels of oxaloacetate dependent on?
Propionate
• What is the fate of excess fatty acids and acetyl CoA?
Excess fatty acids converted back into TG and stored in hepatocytes, excess acetyl CoA diverted into ketones
• What are the clinical signs of excess ketone production?
Fruity smell to breath, ketoacidosis, CNS depression, lowers appetite
• What export pathway can be utilised to cope with excess TGs in the liver?
Can be exported from the liver in VLDL, not very responsive in cows
• How is obesity linked to insulin resistance?
Accumulation of lipid in adipocytes alters the density of insulin receptors on membranes and insulin signalling, loss of the dampening effect insulin normally exerts on HSL
