# Explain how the endocrine system responds when blood glucose concentration falls below the optimum level.

> OCR GCSE Biology A: Gateway Science (J247) — B3.2 Coordination and control — the endocrine system · Explain · 4 marks

> During a long-distance run, a competitor's blood glucose concentration begins to drop significantly below the normal level.

## Mark scheme (4 marks)

1. The pancreas detects the fall in blood glucose concentration and secretes glucagon
2. Glucagon is a hormone that travels in the bloodstream to target organs
3. Glucagon causes the conversion of glycogen into glucose in the liver
4. This raises blood glucose concentration back to the optimum level / this is an example of negative feedback

## Key terms

- [endocrine system](https://www.gradenine.co.uk/glossary/endocrine-system)

## Related

- [Revision notes for OCR GCSE Biology A: Gateway Science (J247)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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