Control of glycogen metabolism & diabetes (lecture 29) Flashcards
what happens in the muscle during exercise?
high energy requirement glycolysis increases glucose uptake increase glycogen breakdown increases glycogen synthesis decreases
what happens in the muscle at rest?
low energy requirement glycolysis decreases glucose uptake decrease glycogen breakdown decreases glycogen synthesis increases
what happens in the liver after a meal?
high blood sugar
glucose release decreases
glycogen breakdown decreases
glycogen synthesis increases
what happens in the liver during fasting/exercise?
low blood sugar
glucose release increases
glycogen breakdown increases
glycogen synthesis decreases
what 3 hormones regulate glycogen metabolism?
epinephrine
glucagon
insulin
what does epinephrine do?
stimulates glycogen breakdown to fuel emergencies
glycogen breakdown increases glycogen synthesis decreases acts on muscle and liver cells acts via GPCRs initiates cAMP-dependent phosphorylation cascade
what do beta cells in the pancreas secrete?
insulin
what do alpha cells in the pancreas secrete?
glucagon
why are islet cells in the pancreas highly vascularised?
for glucose sensing
high oxygen and nutrient demand
what does glucagon do?
raises blood sugar levels
glucose release increases glycogen breakdown increases glycogen synthesis decreases gluconeogenesis increases increase in blood sugar levels
what does insulin do?
lowers blood sugar levels
glucose release decreases glycogen breakdown decreases glycogen synthesis increases gluconeogenesis decreases decrease in blood sugar levels
what does phosphorylation do to glycogen phosphorylase?
activates it
what does phosphorylation do to glycogen synthase?
inactivates it
how do epinephrine and glucagon act via GPCRs?
hormone binds
causes alpha subunit to bind GTP
activates adenyl cyclase
ATP converted to cAMP
PKA activated
• inactivates glycogen synthase a to glycogen synthase b to inhibit glycogen production
• activates phosphorylase kinase (b to a) which breaks down glycogen to glucose-1-phosphate
what does insulin act via?
receptor tyrosine kinase (RTK)
