Glucose homeostasis

Glucose homeostasis is the balance of two hormones (insulin and glucagon) to maintain the blood glucose level.

When the blood glucose level is high, the beta cells in the Islets of Langerhans in the pancreas stimulate the release of insulin into the blood. This causes a series of events to occur.

These include:

• Increased rate of glucose transport into the cells.
• Increased rate of ATP generation.
• Increased amount of glucose converted to glycogen.
• Increased protein synthesis.

The result of all these actions (most importantly glucose converted to glycogen) causes the blood glucose concentration to decrease and return back to the optimum concentration. The stimulus for insulin to be released also decreases.

An example of when this might occur is after you have eaten a meal or overindulged in chocolate.

Diabetes is a disorder where the immune system attack the beta cells so insulin cannot be produced (Type I) or where the tissues in the body respond to insulin at a much slower rate (Type II).

When the blood glucose level is low, the alpha cells in the Islets of Langerhans in the pancreas stimulate the release of glucagon into the blood. Similarly, this causes a series of events which include:

• Increased breakdown of glycogen to glucose.
• Increased breakdown of fatty acids.
• Increased synthesis of glucose.

Glucose can then be released into the blood from the liver, where the blood glucose concentration rises and returns back to the optimum concentration. The stimulus for glucagon release decreases.

Such processes occur during starvation or kidney failure.

This regulatory process is an example of negative feedback.