Disturbance of metabolism

Question 1

How does carbohydrate metabolism change in DM?

Answer 1

Blood glucose increases but cells are glucose deficient.

Glycognolysis and gluconeogenesis occur which compounds hyperglycaemia

Question 2

How is protein metabolism altered in DM?

Answer 2

Insulin cannot promote the uptake of AA into cells. They are used to fuel gluconeogenesis, so lost from tissue

Question 3

How is triglyceride metabolism altered in DM?

Answer 3

Insulin does not increase so cannot inhibit lipolysis. Fatty breakdown occurs. More acetyl CoA formed through beta oxidation. Lots of ketone bodies formed from the excess acetyl CoA. Acetoacetate normally promotes insulin production but this doesn’t occur so the cycle continues

Question 4

How does fructose enter metabolism?

Answer 4

Slow - fructose to fructose-6-p by hexokinase

Fast - fructose to fructose-1-p by fructokinase to dihydroxyacetone-p

Question 5

What occurs in fructosuria?

Answer 5

Hepatic fructokinase is not made so fructose cannot enter metabolism through fast pathway.
Goes via slow pathway so fructose builds up in the blood and spills out into urine

Question 6

What causes hereditary fructose intolerance?

Answer 6

Failure to produce fructose-1-p Aldolase which converts fructose-1-p to dihydroxyacetone-p.
Inorganic phosphate trapped. Cannot activate glycogen phosphorylase and fructose-1,6-phosphatase so glycogenolysis and gluconeogenesis cannot occur