Insulin and glucagon work together as part of
a negative feedback system. As a result of
glucagon secretion, the liverreleases extra
glucose to increase the concentration in the blood.
Muscle cells do not have receptors for glucagon
and so do not respond to it.
This is question 9, taken directly from the specimen
paper for summer 2016 so you won’t have to worry
about the phrasing 🙂 It is for glucagon but will work
fine with adrenaline.
(the numbers marked are according to the mark scheme and not the diagram below)
1. glucagon binds to receptors in cell surface membrane (of liver cell)
2. receptor changes conformation
3. G-protein activated
4. adenylate cyclase activated
5. ATP converted to cyclic AMP
6. (cyclic AMP is) second messenger
7. (cyclic AMP) activates kinase protein
8. enzyme cascade: amplifies original signal of glucagon
9. ref. phosphorylase enzyme(s) / glycogen phosphorylase
10. glycogen broken to glucose
11. glucose, diffuses / passes out, of (liver) cell (into the blood)
12. through GLUT2 transporter proteins
13. AVP ; e.g. ref. to stimulating gluconeogenesis
