which cells detect a decrease in blood glucose concentration
alpha and beta cells of the islets of Langerhans
how do alpha cells respond to a decrease in blood glucose concentration
by secreting glucagon
how do beta cells respond to a decrease in blood glucose concentration
by stopping the secretion of insulin
STEP 1 ; Detection
a decrease in blood glucose concentration is detected by alpha and beta cells of the islets and secrete glucagon and stop secreting insulin
STEP 2; decreases
the decrease in blood insulin concentration reduces the use of glucose by liver and muscle cells
STEP 3 ; Reception
glucagon binds to receptors in the cell surface membrane of liver cells
STEP 4 ; Change
this binding causes a conformational change in the receptor protein that activates a G protein
STEP 5 ; wake up ady
the activated G protein activates the enzyme adenylyl cyclase
STEP 6 catalysis by ady
active adenylyl cyclase catalyses the conversion of ATP to the second messenger cyclic AMP (cAMP)
STEP 7 ; cAMP kinase
cAMP binds to protein kinase A enzymes and activates them
STEP 8; A Kinase taps P Kinase
active protein kinase A enzymes activate phosphorylase kinase enzymes by adding phosphate groups to them
STEP 9 ; active P kinase tap GPes
active phosphorylase kinase enzymes activate glycogen phosphorylase enzymes
STEP 10 ; GPes instigator
active glycogen phosphorylase enzymes catalyse the breakdown of glycogen to glucose
what process takes place when there is a decrease in blood concentration
Glycogenolysis
what is the importance of the enzyme cascade caused by a decrease in BGC
it amplifies the original signal from glucagon
what is the result of glycogenolysis
releasing of extra glucose by the liver to increase the BGC back to normal