E2 Fructose & Glycogen; Glycogen storage diseases Flashcards
What organ is the primary site of fructose disposal?
liver
The liver is the primary site of ______ disposal.
fructose
What percentage of fructose if extracted by the liver?
70%
What two enzymes, that are highly expressed in the liver, are essential for fructose metabolism?
- Fructokinase
2. Triokinase
If a low-dose of fructose is added to a meal containing glucose, what are three outcomes?
- improved glucose tolerance
- fructose stimulates glucokinase
- threefold increase in net glycogen synthesis
T/F. Small amounts of fructose can cause the release of hexokinase from a regulatory protein.
False; glucokinase (liver)
How does fructose release glucokinase from a regulatory protein?
F-1-P binds to the regulatory protein causing glucokinase to be set free and be activated
T/F. Fructose has a high benefit for muscle glycogen synthesis.
False; no benefit
Will high or low doses of fructose increase liver glycogen synthesis?
low doses
Are high levels of fructose good for the liver?
NO!
Why are high levels of fructose not good for the liver?
- liver has a high uptake
2. increased fat, lactate, and glycerol formation
T/F. HFCS and sucrose are not that different than fructose.
True
Are glycogen storage diseases genetic or developed?
genetic
What causes glycogen storage diseases?
- enzyme deficiencies (glycogenolysis, glycogenesis)
2. abnormal structure
T/F. Glycogen storage diseases have increased storage but same breakdown.
False; increased storage but impaired breakdown
Do Glycogen storage diseases have a large or small spectrum when it comes to being mild or fatal?
large spectrum
What are the three categories of glycogen storage disease?
- liver
- skeletal muscle
- alpha-glucosidase or debranching enzyme deficiency
Glycogen storage diseases will lead to what type of enzyme deficiencies in the liver?
glycogenolysis
Glycogen storage diseases in the liver can lead to _______.
hypoglycemia
Glycogen storage diseases and what other factor will cause hypoglycemia?
enlarged liver
What is an example of a glycogen storage disease in the liver?
von Gierke disease
T/F. von Gierke disease is a Type II glycogen storage disease.
False; Type I
Glycogen storage disease will lead to what type of enzyme deficiencies in skeletal muscle?
glycogenolysis
T/F. Glycogen storage diseases in skeletal muscle will cause glycogenolysis enzyme deficiencies, which in turn will limit glycolysis.
True
What are four negative outcomes of glycogen storage diseases in skeletal muscle?
- low energy production
- muscle weakness
- muscle cramping after exercise
- low lactate levels in blood
What is an example of a glycogen storage disease in skeletal muscle?
McArdle disease
T/F. The glycogen storage disease alpha-glucosidase/debranching enzyme deficiency can occur in only certain tissues.
False; can occur in many tissues and organs
Is the alpha-glucosidase/debranching enzyme deficiency mild or fatal?
Fatal
In alpha-glucosidase/debranching enzyme deficiency, where is there an increased storage of glycogen? What does it cause?
increased storage of glycogen in lysosomes of organ causing Cardiomegaly
What is an example of an alpha-glucosidase/debranching enzyme deficiency (glycogen storage disease)?
Pompe disease
