Blood glucose regulation

The concentration of glucose in the blood must be kept at a set point. The concentration of glucose in a person’s blood can increase after they have eaten a meal containing lots of carbohydrates. The concentration of glucose in a person’s blood can decrease after a period of exercise or if they have not eaten for a long while. Glucose diffuses out of the blood into muscle cells and is broken down to release energy for muscle contractions.

If the blood glucose concentration rises too high then cells can lose water. This may interfere with cell activities.

If the blood glucose concentration falls too much then body cells will not receive as much glucose and so will not be able to release so much energy in respiration.

The concentration of glucose in the blood is regulated by the action of the hormones insulin and glucagon. These hormones are made in the pancreas and act on cells in the liver.

Human body showing the digestive system. The liver is near the top and the pancreas is below.

The liver acts as the body’s glucose 'reservoir'. When the blood glucose concentration gets too high liver cells can take in glucose and store it. When the blood glucose concentration gets too low liver cells can release glucose into the blood.

The diagram below shows how the concentration of glucose in the blood is regulated.

Flowchart showing how blood is regulated in glucose. If an increase in blood glucose the change is detected by cells in the pancreas which releases more insulin and less glucagon into the blood.  Liver cells then remove more glucose from the blood and store it.  If a decrease in blood glucose, the change is detected by cells in the pancreas.  The pancreas releases less insulin and more glucagon into the blood and the liver cells release more glucose into the blood.