IGCSE Biology glossary
Glucagon
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Definition
A hormone produced by the alpha cells of the islets of Langerhans in the pancreas when blood glucose concentration is too low. Glucagon stimulates the liver to convert stored glycogen back into glucose and release it into the blood, raising blood glucose levels.
What to include in an exam answer
Glucagon RAISES blood glucose. Insulin and glucagon are antagonistic hormones. A common error is confusing glucagon with glycogen. Glucagon is a HORMONE; glycogen is a STORAGE carbohydrate.
Example in context
Distinguish between glucagon and glycogen (2 marks): Glucagon is a hormone produced by the pancreas that stimulates the liver to convert glycogen into glucose. Glycogen is a storage polysaccharide made of glucose molecules, stored in the liver and muscles.
Related syllabus topic
Coordination & responseRelated terms
- Homeostasis
- Negative feedback
- Tropism
- Reflex arc
- ADH
- Insulin
- Adrenaline
- Synapse
- Neurone
- Sensory neurone
- Motor neurone
- Relay neurone
- Receptor
- Effector
- Cornea
- Iris
- Lens
- Retina
- Optic nerve
- Accommodation
- Type 1 diabetes
- Type 2 diabetes
- Hormones
- Endocrine gland
- Auxin
- Thermoregulation
- Vasoconstriction
- Vasodilation
- Sweating