007 The normal Endocrine Pancreas

Question 1

Does GIP increase or decrease glucagon release?

Answer 1

Increases

Question 2

Which alpha receptor decreases insulin release

Answer 2

a2 decreases insulin release

a1 increases insulin release

Question 3

Glycogen synthase vs. Glycogen phosphorylase

Which is active in phosphorylated form and which is active in dephosphorylated form?

Answer 3

Glycogen synthase is active in dephosphorylated form

Glycogen phosphorylase is active in phosphorylated form

Question 4

How does insulin activate glycogen synthetase?

Answer 4

1. Insulin will inhibit the cAMP pathway to prevent cAMP dependant kinases from phosphorylating glycogen synthetase. It also activates phosphoprotein phosphatase, which dephosphorylates glycogen synthetase.

Question 5

How does glucagon activate glycogen phosphorylase

Answer 5

It will activate adenylate cyclase, increasing cAMP dependant kinases pKA and pKB to phosphorylate glycogen phosphorylase from GPb to GPa.

It also switches glycogen synthetases off by phosphorylation. It also inhibits phosphoprotein phosphatase.

Question 6

What effect does insulin have on acetylCoA carboxylase?

Answer 6

Will increase acetylCoA decarboxylase to generate malonyl CoA and fatty acids

1. Activates phosphoprotein phosphatase
2. dephosphorylates and activates acetyl CoA carboxylase
3. Inhibits cAMP independent kinases
4. Prevents phosphorylation and inactivation of acetylCoA carboxylase.

Question 7

What effect does insulin have on cAMP dependant kinases?

Answer 7

It will inhibit cAMP independent kinases

Question 8

Explain insulin secretion?

Answer 8

1. Glucose increases ATP/ADP ratio
2. K+ ATP sensitive channels inactivate
3. Depolarisation causes Ca2+ influx
4. Release of insulin

Question 9

How does insulin trap glucose in the cell?

Answer 9

Activates hexokinase