Explain how the body responds to maintain a constant blood glucose concentration during vigorous exercise.

Eduqas GCSE Biology — 2.5.2 Hormonal coordination · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

During vigorous exercise, muscles use glucose rapidly for respiration. This causes blood glucose concentration to fall.

Model answer (4 marks)

1. The pancreas senses the drop in blood glucose concentration.
2. In response, the pancreas releases the hormone glucagon into the bloodstream.
3. Glucagon travels through the blood to the liver.
4. In the liver, glucagon stimulates the breakdown of glycogen into glucose, which is then released into the blood to restore normal glucose levels.

Examiner tips

Use the exact sequence of events: pancreas → glucagon → liver → glycogen breakdown. Include the word "stimulates" to show hormonal action. Mention that glucose is released into the blood to maintain concentration.

Common mistakes

Confusing insulin with glucagon. Omitting the step that glucagon acts on the liver. Using vague terms like "the body" instead of specifying pancreas and liver.

Mark scheme (4 marks)

The pancreas detects the fall in blood glucose concentration
The pancreas releases glucagon
Glucagon travels in the blood to the liver
The liver converts glycogen into glucose (glycogen is broken down), releasing glucose into the blood

Key terms in this question

blood glucose concentration