Insulin/Glucagon Question?

Question

Insulin inhibits glucagon release BUT why does glucagon STIMULATE release of insulin?

Answer 1

Insulin inhibits glucagon release BUT why does glucagon STIMULATE release of insulin?


Glucagon does not directly stimulate release of Insulin. It is a cycle and negative feedback mechanism of glycogenesis and glucogenesis. In state of starvation, hunger, or decrease/low bood glucose level, glycogenolysis will be stimulated. Glycogenolysis pathway(breakdown of stored glycogen in liver cell not in muscle cell) Glucagon stimulates the debranching enzyme(cis and trans) to cut-off glycogen to form free Glucose. Where as in a state of high glucose blood level a negative feed back mechanism will occur. Insulin from Beta cells of Pancreas wiil be stimulated(Glucagon came from Alpha cell of pancreas). Insulin will stimulate the glycogenesis pathway.
Where-in the excess glucose will be stored as glycogen to liver and muscle cells.

I made this explanation as brief and easy for you to understand. But if you are really interesterested in molecular level. Check out and read Carbohydrates Metabolism of Biochemistry book of Harpers. I hope this one is helpful to you.GoodLuck!

Answer 2

It's a simple logic. When glucagon is released, the body needs glucose. Glucagon acts on liver primarily to convert stored glycogen into glucose. The glucose is then released into blood. However for glucose to be absorbed by tissues in the body such as the muscles, insulin is required. Therefore insulin is stimulated at the same time. So Insulin in this case acts as a modulatory of blood sugar levels.

Answer 3

This is fuzzy for me, but here we go.

Glucagon is similar to epinephrine in action, and they both get released at the same time. (Low blood sugar results in rapid heart rate because of the action of epinephrine on the heart.) The pancreatic islet cells, in particular the beta cells (insulin) are stimulated in part by beta receptors. Therefore, when glucagon/epi is released, insulin is stimulated. This is to prevent hyperglycemia. Wether the glucagon is directly acting, or indirectly through epi, is unclear to me. Hope that helps somewhat.

Answer 4

Glucagon consists of a single chain of 29 amino acids and the first six amino acids bind to specific receptors in the liver. In turn, a cycle of events happen: the increased production of cAMP-> increased destruction of stored glycogen-->increased gluconeogenesis and ketogenesis-->which leads to an increase of blood glucose from the liver storage of glycogen.