Secondary messenger model

step 1

low blood glucose concentration detected by chemoreceptors

step 2

adrenaline and glucagon bind to cell receptors

step 3

activate adenylate cyclase

step 4

converts ATP to cyclic AMP

step 5

cAMP activates the enzyme protein kinase A

step 6

protein kinase A activates glycogenolysis and gluconeogenesis and inhibits glycogenesis