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Hormonal control of blood glucose
Describe how blood glucose concentration is maintained within narrow limits in people who do not have diabetes.
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Marking points
- 1 Links high/increasing blood glucose to insulin release by the pancreas.
- 2 Explains insulin-driven movement of glucose into liver or muscle cells.
- 3 Explains conversion of excess glucose to glycogen in liver or muscle.
- 4 Links low/decreasing blood glucose to glucagon release by the pancreas.
- 5 Explains glucagon-driven conversion of glycogen to glucose and its release into blood.
Full-mark answer
When blood glucose rises, the pancreas releases insulin. Insulin causes glucose to move from the blood into liver and muscle cells, where excess glucose is converted to glycogen, lowering blood glucose. When blood glucose falls, the pancreas releases glucagon. Glucagon causes glycogen to be converted back into glucose and released into the blood, raising the concentration again.
Why this answer loses marks
Insulin lowers blood glucose and glucagon raises it.
The directions are right but the mechanism is incomplete: include glucose uptake and glycogen storage, then glycogen conversion and glucose release.