How is blood glucose maintained in the body?

The control of blood glucose levels is an example of homeostasis. The human body requires glucose for normal respiration of cells, but the blood levels is in a narrow range.

Insulin and glucagon are hormones released from the pancreas into the blood stream. They are called endocrine hormones, because they are in the blood stream (endocrine).

How Insulin Controls Blood Glucose

Insulin is secreted from the islet cells in the pancreas - in beta cells. HIGH blood glucose stimulates the release of insulin. There is a low level of insulin secreted by the pancreas, but in high glucose levels, more insulin is released into the blood stream. LOW blood glucose results in less secretion of insulin.

In HIGH blood glucose, insulin in the blood stream causes glucose to enter cells resulting in a net reduction in blood glucose - into the normal range.

In LOW blood glucose, more glucagon is released.

The Effect of Glucagon On Blood Glucose

Glucagon is also released by the pancreas, but it acts on liver cells to release glucose contained in glycogen molecules - this is called glycogenolysis (the breakdown of glycogen into glucose).

Glucagon can also stimualte the liver to produce glucose out of other nutrients in the body, like proteins.

If glucose levels are too low then glucagon is released, which results in an increase in blood glucose back to the normal range.