Regulation of Metabolism Flashcards
Where is glycogen synthesised?
After a meal - in the liver.
At rest - in muscle.
How do glycogen stores change overnight?
They decrease, as they are used to generate glucose for the needs of the body.
What are the products of one cycle of beta oxidation?
Releases one molecule of acetyl-CoA, FADH2 and NADH.
When are ketone bodies produced?
During a few days of fasting.
What happens when there is an excess of acetyl-CoA?
Acetoacetyl-CoA is converted to ketone bodies in liver mitochondria. This is ketogenesis.
What is ketogenesis?
Conversion of acetoacetyl-CoA to ketone bodies (e.g. Acetoacetate or beta-hydroxybutyrate).
What happens when there’s too many ketone bodies in the blood?
Ketoacidosis - blood pH drops.
What tissues can ketone bodies provide energy to?
Almost all - can provide 70% of energy to brain during starvation, can’t provide any to erythrocytes.
What is gluconeogenesis?
Conversion of pyruvate to glucose.
How can pyruvate be formed in starvation?
From glucogenic amino acids and from glycerol (which is released from triglycerides by lipolysis).
What does insulin do?
It is an anabolic hormone - it promotes glucose uptake by cells, where it is synthesised into glycogen and fat.
Increased glycogen synthesis, lipogenesis and glycolysis but decreased gluconeogenesis, glycogenolysis and ketogenesis.
How does insulin cause lipogenesis?
It activates the hormone acetyl-CoA carboxylase, which allows acetyl-CoA to be converted to malonyl-CoA.
What is the action of glucagon?
Acts on the liver, stimulating gluconeogenesis, glycogenolysis and ketogenesis. It shuts down glycogen and lipid synthesis. Causes an elevation of blood glucose levels.
What is the effect of adrenaline in metabolism?
Inhibits insulin secretion.
What is the effect of cortisol in metabolism?
In the long term, has catabolic effects.
What does hormone sensitive adipose tissue lipase (HSL) do?
Regulated release of fatty acids from stored triglycerides in adipose tissue.
How does insulin work after a meal?
Inhibits HSL, so triglycerides aren’t broken down to fatty acids. Glucose is taken up by cells and fatty acid synthesis increases.
What happens to glucose after a mixed meal?
It is transported from the intestine to the liver, brain, muscle and adipose tissue.
What is diabetes?
A disorder of reduced insulin production or reduced response to insulin.
What occurs in diabetes?
Increased gluconeogenesis, glycogenolysis and ketogenesis.
Decreased glycogen synthesis, lipogenesis and glycolysis.
Can cause ketoacidosis.
