Question

Describe the chain of events where high blood glucose causes insulin release from pancreatic cells, and ultimately alters the metabolism inside of cells.

Answer 1

In the absorptive state, an increase in blood glucose level is monitored by the beta cells of the pancreatic islets, causing them to elevate the release of insulin into the blood. The role of Insulin is to stimulate the cells, especially adipose and muscle cells, to take up glucose from the blood.

To enter cells, glucose needs trans-membrane transporters and there is a family of these transporters referred to as GLUT transporters (GLUcose Transporter). GLUT4 is found on muscle and fat cells.When insulin ligand binds to insulin receptors on the cell membrane, cells get stimulated to express more number of glucose transporters.When more transporters are expressed, more glucose is being transported into cells which reduces the blood glucose levels.

Insulin hormone also has a role on other pathways which contribute to an increase in glucose usage and storag, therefore a reduction in blood glucose. These include:

- Increasing the rate of glycolysis, a process that breaks down glucose for cellular energy;

- It promotes glycogenesis, a process which converts glucose into glycogen for storage;

- It inhibits lipolysis, a process which breaks down lipids to release energy.

These effects of insulin modify the metabolism away from fat and towards glucose. In a nutshell insulin modulates the body to utilise carbohydrates as a source of energy than its fat reserves..