Glycogenolysis (Glycogen Degradation) Flashcards
For mobilizing stored glycogen
Glycogenolysis
Site of Glycogenolysis
Liver and Muscle
CYTOSOL
Substrate of Glycogenolysis
Glycogen
Products of Glycogenolysis
Glucose in liver
Glucose 6-phosphate in muscle
Rate Limiting Step of Glycogenolysis
Shortening of glycogen chains
GLYCOGEN PHOSPHORYLASE
Cleave the a 1,4 linkage
Removes glucose 1-P molecules
Shortens the glycogen chain
Releases GLUCOSE 1 PHOSPHATE NOT free glucose
GLYCOGEN PHOSPHORYLASE
End product of glycogenolysis in MUSCLE
Glucose 6-phosphate
End product of glycogenolysis in LIVER
Glucose
Severe fasting hypoglycemia
INCREASED glycogen in the liver and kidneys
INCREASED blood lactate, TGL, uric acid and hepatomegaly
LIVER DOES NOT REGULATE BLOOD GLUCOSE
VON GIERKE DISEASE
(type I)
Glucose 6-Phosphatase
hypoglycemia
lactic acidosis
hyperlipidemia
hyperuricemia
CARDIOMEGALY, hypertrophic cardiomyopathy, hypotonia, exercise intolerance and systemic findings lead to early death
POMPE DISEASE (type II)
lysosomal acid a (1,4) glucosidase (acid maltase)
Similar to Von Gierke disease but milder symptoms and NORMAL lactate levels
Can lead to cardiomyopathy
Limit dextrin like structures accumulate in cytosol
CORI DISEASE (type III)
Debranching enzymes (a-1,6 glucosidase and 4 a-D glucanotransferase)
INCREASED glycogen in muscle but muscle cannot break it down –> PAINFUL MUSCLE CRAMPS
MYOGLOBINURIA (red urine) w/ strenuous exercise and arrhythmia from electrolyte abnormalities
MCARDLE DISEASE (type V)
Glycogen Phosphorylase (Myophosphorylase)
Hepatosplenomegaly, INCREASE polysaccharide with few branch points, death from heart or liver failure before age 5
ANDERSEN DISEASE (type IV)
Branching Enzyme
Hepatomegaly, mild hypoglycemia
HERS DISEASE (type VI)
Liver Phosphorylase
