A doctor is investigating a patient who has unusually high blood glucose levels throughout the day. The doctor suspects the patient's endocrine system is not functioning correctly. Explain how hormonal communication normally works in the body to regulate blood glucose levels, including how the hormone reaches its target organ.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
The endocrine system uses hormones to communicate between different parts of the body. Hormones are released directly into the bloodstream and travel to target organs where they produce an effect.
Model answer (5 marks)
1. The pancreas, acting as a gland, senses the rise in blood glucose and secretes insulin.
2. Insulin is released directly into the bloodstream.
3. It travels through the blood to its target organs – the liver and body cells.
4. Only cells with insulin receptors respond, as the receptors are complementary to insulin.
5. In the target cells, insulin promotes uptake of glucose and conversion to glycogen, lowering blood glucose levels.
2. Insulin is released directly into the bloodstream.
3. It travels through the blood to its target organs – the liver and body cells.
4. Only cells with insulin receptors respond, as the receptors are complementary to insulin.
5. In the target cells, insulin promotes uptake of glucose and conversion to glycogen, lowering blood glucose levels.
Examiner tips
- Use the word ‘secretes’ for hormone release. Mention the pancreas as the gland. Show the pathway: pancreas → bloodstream → target organ. Explain receptor specificity. State the physiological effect on glucose.
- common_mistakes
- :
- Confusing glucagon for insulin. Saying the hormone acts on all cells. Omitting the pancreas as the gland.
Mark scheme (5 marks)
- A gland (the pancreas) detects a change / stimulus (rise in blood glucose) and secretes a hormone (insulin)
- The hormone is released directly into the bloodstream
- The hormone travels in the bloodstream to the target organ (the liver / body cells)
- Only the target organ responds because it has complementary receptors for that specific hormone
- The target organ responds to lower blood glucose levels, e.g. the liver converts glucose to glycogen for storage
Key terms in this question
hormone · endocrine system · target organ
Related
- All OCR A-Level Biology B — Advancing Biology (H422) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
More Hormonal communication questions
- A woman is trying to become pregnant. Her doctor explains that hormones control …
- A athlete is preparing for a marathon. During training, their blood glucose leve…
- A teenager is diagnosed with Type 1 diabetes. Their pancreas no longer produces …
- A student is learning about hormonal communication in the human body. Explain ho…