Explain how the endocrine system and the digestive system are integrated to regulate blood glucose concentration after a carbohydrate-rich meal.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
1. Digestion of carbohydrates in the small intestine releases glucose, which is absorbed into the blood, causing blood glucose concentration to rise.
2. The rise in blood glucose is detected by beta cells in the islets of Langerhans in the pancreas, which is an endocrine gland.
3. Beta cells secrete insulin into the blood, which travels to target cells (liver, muscle, adipose tissue).
4. Insulin stimulates uptake of glucose by cells and promotes conversion of glucose to glycogen (glycogenesis) in the liver/muscle, lowering blood glucose back to the normal range.
2. The rise in blood glucose is detected by beta cells in the islets of Langerhans in the pancreas, which is an endocrine gland.
3. Beta cells secrete insulin into the blood, which travels to target cells (liver, muscle, adipose tissue).
4. Insulin stimulates uptake of glucose by cells and promotes conversion of glucose to glycogen (glycogenesis) in the liver/muscle, lowering blood glucose back to the normal range.
Examiner tips
- Use the exact terminology: beta cells, insulin, glycogenesis. Show the sequence of events in order. Mention the target tissues (liver, muscle, adipose).
Common mistakes
- Confusing glucagon with insulin. Omitting the detection of glucose rise by beta cells. Using vague terms like "hormone" without specifying insulin.
Mark scheme (4 marks)
- Digestion of carbohydrates in the small intestine releases glucose, which is absorbed into the blood, causing blood glucose concentration to rise.
- The rise in blood glucose is detected by beta cells in the islets of Langerhans in the pancreas, which is an endocrine gland.
- Beta cells secrete insulin into the blood, which travels to target cells (liver, muscle, adipose tissue).
- Insulin stimulates uptake of glucose by cells and promotes conversion of glucose to glycogen (glycogenesis) in the liver/muscle, lowering blood glucose back to the normal range.
Key terms in this question
endocrine system · digestive system · blood glucose concentration
Related
- All IB DP Biology Standard Level (2023 syllabus) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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