Higher Insulin-Glucagon Negative Feedback in Detail
Part of Glucose Regulation — GCSE Biology
This higher tier covers Higher Insulin-Glucagon Negative Feedback in Detail within Glucose Regulation for GCSE Biology. Topic 6: Glucose Regulation It is section 12 of 15 in this topic. This section is most useful once the core foundation idea is secure, because it adds the detail that pushes answers higher.
Topic position
Section 12 of 15
Practice
15 questions
Recall
20 flashcards
Higher Insulin-Glucagon Negative Feedback in Detail
At higher tier, you are expected to know the detailed negative feedback mechanisms for both hormones and to describe HbA1c testing:
Detailed insulin pathway:
- High blood glucose → detected by beta cells in islets of Langerhans (pancreas)
- Insulin secreted → binds to insulin receptors on liver and muscle cell surfaces
- Glycogenesis: glucose → glycogen (storage); cells also increase glucose uptake for respiration
- Blood glucose falls → beta cells reduce insulin secretion → negative feedback complete
Detailed glucagon pathway:
- Low blood glucose → detected by alpha cells in islets of Langerhans (pancreas)
- Glucagon secreted → binds to glucagon receptors on liver cells
- Glycogenolysis: glycogen → glucose; glucose released into blood
- Blood glucose rises → alpha cells reduce glucagon secretion → negative feedback complete
HbA1c testing: Glycated haemoglobin (HbA1c) is a form of haemoglobin that has glucose permanently bound to it. The proportion of HbA1c in the blood reflects the average blood glucose level over the previous 2–3 months. A high HbA1c indicates persistently elevated blood glucose — a strong indicator of poorly controlled diabetes. HbA1c testing provides a more reliable long-term measure than a single glucose reading, which can vary throughout the day.