Glycogen structure and metabolism overview — Flashcards

Flashcard 1: Which glycogen storage disorder is associated with severe fasting hypoglycemia? _____

Answer: Von Gierke disease

Flashcard 2: Glycogen phosphorylase is stimulated by _____ in the liver

Answer: glucagon

Flashcard 3: Dephosphorylation of glycogen synthase causes enzyme _____ (activation/inactivation)

Answer: activation

Flashcard 4: Glucokinase is induced by _____

Answer: insulin

Flashcard 5: What is the rate-limiting enzyme for glycogenolysis? _____

Answer: Glycogen phosphorylase

Flashcard 6: In skeletal muscle, glycogenolysis ultimately produces _____, which is rapidly metabolized during exercise

Answer: glucose-6-phosphate

Flashcard 7: glycogen synthesis

Answer: glycogen synthase

Flashcard 8: Rate-limiting enzyme of glycogenolysis

Answer: glycogen phosphorylase

Flashcard 9: What is the enzyme deficiency in McArdle's disease (GSD type V)?

Answer: Deficiency of skeletal muscle glycogen phosphorylase (myophosphorylase) :: enzyme deficiency?

Extra: - Presentation: Painful muscle cramps, myoglobinuria (rhabdomyolysis) with strenuous exercise, and "second-wind" phenomenon. - Pathophysiology: Glycogen accumulation in muscle; cannot break down glycogen to glucose-1-phosphate. - Genetics: Autosomal Recessive (AR). - Mnemonic: Very Poor Carbohydrate Metabolism (Von Gierke, Pompe, Cori, McArdle).

Flashcard 10: Cori's disease (GSD type III) is caused by a deficiency in which enzyme?

Answer: Debranching enzyme deficiency (α-1,6-glucosidase) \n\nCharacterized by: hepatomegaly, fasting hypoglycemia, normal blood lactate levels, and accumulation of limit dextrin-like structures.

Extra: Inheritance: Autosomal Recessive (AR)\nMnemonic: Very Poor Carbohydrate Metabolism (Von Gierke, Pompe, Cori, McArdle) - although Cori is Type III. \n\nNote: Blood lactate is normal in Cori's disease, unlike Von Gierke's (Type I) where it is elevated. Muscle involvement (weakness) can also be seen in Cori's.