Explain why the release of insulin from beta cells in the islets of Langerhans can be described as an example of hormonal communication rather than nervous communication.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
After a carbohydrate-rich meal, blood glucose concentration rises significantly above the normal range. Specialised cells in the pancreas detect this change and release a chemical messenger directly into the blood.
Model answer (4 marks)
Insulin is secreted directly into the blood, not along a neurone or nerve fibre.
It acts on target cells or organs that are at a distance from the pancreas, rather than at a specific synapse.
Insulin binds to specific complementary receptors on the membranes of target cells, a receptor‑mediated response.
The resulting effect is slower and longer‑lasting than a nervous signal, which uses rapid electrical impulses along neurones.
It acts on target cells or organs that are at a distance from the pancreas, rather than at a specific synapse.
Insulin binds to specific complementary receptors on the membranes of target cells, a receptor‑mediated response.
The resulting effect is slower and longer‑lasting than a nervous signal, which uses rapid electrical impulses along neurones.
Examiner tips
- Use the word ‘secreted directly into the blood’ to show endocrine nature.
- Mention the distance from release site to target cells.
- Highlight receptor‑mediated action.
- Compare speed and duration with nervous communication.
Common mistakes
- Confusing insulin with a neurotransmitter or saying it acts locally.
- Failing to mention the blood as the transport medium.
- Overlooking the receptor‑mediated mechanism.
Mark scheme (4 marks)
- Insulin is secreted directly into the blood (not along a neurone/nerve fibre)
- Insulin acts on target cells / target organs at a distance from its site of release (rather than at a specific synapse)
- Insulin binds to specific complementary receptors on target cell membranes (receptor-mediated response)
- The response is slower and longer-lasting compared with nervous communication, which uses electrical impulses along neurones
Key terms in this question
islets of Langerhans · beta cells · hormonal communication
Related
- All OCR A-Level Biology A (H420) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
More Hormonal communication questions
- Explain why the effects of adrenaline on target cells are short-lived compared w…
- Explain why the hormonal response to a stressor is slower to begin but longer la…
- Explain why a hormone such as adrenaline can only affect certain cells in the bo…
- Explain why a hormone such as adrenaline can only affect certain cells in the bo…