Ketones Flashcards
Ketones
water soluble molecule derived from lipids
can be used in place of glucose to provide acetyl-CoA for krebs cycel
Does acetone ionize appreciably?
no
but acetoacetic acid does
ketosis
elevated ketones concentration in tissues (usually measured in blood)
Ketonemia
elevated levels of ketones in the blood
ketonuria
presence of ketones in the urine
Ketoacidosis
metabolic acidosis resulting from excessive production of ketones
Predominant source of ketones in healthy animals
long chain fatty acids
In hepatocytes LCFAs can be used to:
synthesize TGs for export in VLDLs (mainly)
produce acetly-CoA for the krebs cycle by undergoing beta-oxidation in mitochondria
LCFA must be bound to _____ in order to enter mitochondrion
carnitine
___ acetyl-CoA units are condensed to form acetoacetate, which can be further metabolized into beta hydroxybutyrate and acetone
2
Ketones are particularly taken up by?
cardiac and skeletal muscle
Most ketones are used to fee?
the krebs cycle in peripheral tissues to generate ATP
Can the brains of many veterinary species utilize ketone? Can humans?
No- require glucose
yes
The most abundant rumen VFA is?
acetate
The next most abundant VFA in the rumen is?
propionate
-almost all of it enters the liver and enters gluconeogenesis pathway
The least abundant rumen VFA is?
butyrate
Ruminants are at greatests risk of ketoacidosis because they have
two sources of ketones
- LCFAs mobilized from adipose for energy
- VFAs from fermentation
Ketosis triggers
starvation or anorexia
lactation or late pregnancy
insulin deficiency
What causes excessive ketone production
- lipolysis during states of negative energy balance
- increased acetyl-CoA production from LCFA in liver
- negative energy balance also diverts oxaloacetate into the gluconeogenesis pathway
Negative energy balance states include?
fasting or starvation
type I diabetes
late pregnancy or lactation
Why do ruminants have a greater risk of fatty liver?
because they are less efficient than other species at exporting VLDLs from hepatocytes
Fatty liver is common in dogs and cats because?
with diabetes mellitus fat is mobilized for energy as cells fail to take up glucose and VLDL synthesis in the liver cannot keep up with TG synthesis
pregnancy toxemia
ketoacidosis during late pregnancy when when cows/ewes cannot take in as much feed as usual
Clincial signs of ketosis
Appetite suppression/anorexia Weight loss Weakness Decreased milk production fat accumulation in liver and liver damage
