Control of Blood Glucose: Insulin and Glucagon — AQA GCSE Biology

Blood glucose concentration must be controlled to keep cells supplied with energy without becoming dangerously high or low. The pancreas does this.

Monitoring and control

The pancreas continuously monitors and controls the blood glucose concentration. It uses two hormones in a negative feedback system.

When blood glucose is too high

• The pancreas releases insulin.
• Insulin causes liver and muscle cells to take up glucose from the blood.
• Excess glucose is converted into glycogen for storage in the liver and muscles.
• Blood glucose returns to normal.

When blood glucose is too low (Higher Tier)

• The pancreas releases glucagon.
• Glucagon causes the liver to convert glycogen back into glucose, which is released into the blood.
• Blood glucose returns to normal.

Negative feedback

This is a clear example of negative feedback: a change in blood glucose triggers a response that reverses the change and restores the normal level.

Exam tips

• Insulin lowers blood glucose (stores it as glycogen); glucagon raises it.
• Glucose is stored as glycogen (don't confuse with glucagon).
• Explain the system using negative feedback.
• The pancreas both monitors and controls blood glucose.