Controlling Blood Glucose Concentration

The pancreas regulates the concentration of glucose in the blood using the hormones insulin and glucagon.

Insulin is a hormone produced in the pancreas that causes cells to take up glucose and stimulates liver and muscle cells to convert glucose to glycogen (a polymer of glucose) for storage.

Illustration titled "How Insulin Works" showing the process of glucose entering a cell. On the left, a cell with a closed glucose channel is depicted with glucose molecules outside and an insulin molecule approaching a glucose receptor. On the right, upon insulin's interaction with the receptor, the glucose channel opens, allowing the glucose to enter the cell. The stages are labelled as "Closed" for the inactive cell and "Open" for the cell allowing glucose entry.
  • If the concentration of glucose in the blood is too high, cells of the body lose water by osmosis, which damages them

Glucagon is a hormone produced in the pancreas that stimulates liver and muscle cells to break down glycogen into glucose and release it back into the bloodstream.

The diagram below shows this negative feedback cycle and the relationship between insulin and glucagon.

Illustration showing the regulation of blood glucose levels by insulin and glucagon. At the top, when there's a high blood glucose level after eating, the pancreas releases insulin which stimulates cells to take up glucose, bringing the blood glucose level to normal. This is depicted with arrows from the pancreas, through insulin molecules, to the liver and cells. At the bottom, when blood glucose levels drop, the liver releases glucose into the bloodstream under the influence of glucagon from the pancreas. The liver's storage of glucose and glycogen is also highlighted.

Maintaining blood glucose concentration within an ideal range is an example of homeostasis.

When blood glucose levels are too low:

1. The pancreas releases glucagon into the bloodstream

2. Glucagon stimulates glycogen breakdown in the liver, converting it into glucose

3. This increases the concentration of glucose in the blood back to normal levels

When the blood glucose levels are too high:

1. The pancreas releases insulin into the bloodstream

2. Insulin stimulates the liver to convert glucose into glycogen and it causes cells to take up glucose

3. This decreases the concentration of glucose back to normal levels

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