AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Control of blood glucose concentration: (HT only) Students should be able to explain how glucagon interacts with insulin in a negative feedback cycle to control blood glucose (sugar) levels in the body.
Blood glucose must stay steady for cells to respire reliably.
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Blood glucose must stay steady for cells to respire reliably. After a meal, rising glucose is detected by the pancreas, which secretes insulin. Insulin causes liver and muscle cells to take up glucose and store it as glycogen, so glucose falls. If glucose falls too low, the pancreas secretes glucagon instead. Glucagon makes liver cells break glycogen down into glucose, which is released into the blood, so glucose rises. Each hormone therefore reverses the other's effect, forming a negative feedback cycle that keeps glucose within a narrow range.
For example: After exercise glucose dips, glucagon restores it; after a sugary drink, insulin lowers it.
What earns the marks
- Insulin is secreted by the pancreas when blood glucose concentration is too high.
- Insulin increases the uptake of glucose by cells and stimulates the conversion of glucose to glycogen in the liver and muscles.
- Glucagon is secreted by the pancreas when blood glucose concentration is too low.
- Glucagon stimulates the liver to convert stored glycogen back into glucose, which is released into the blood.
- The two hormones have opposite effects, so each corrects a deviation and restores the set point, which is negative feedback.
Common mistakes and how to put them right
Saying insulin and glucagon are secreted by the liver.
Put it right: Both are secreted by the pancreas, and the liver is the main target organ.
Stating that glucagon is released when glucose is too high.
Put it right: Glucagon is released when glucose is too low, while insulin is released when it is too high.
Describing the cycle as positive feedback.
Put it right: Because the response reverses the original change and returns glucose towards normal, it is negative feedback.
Exam tips
- Use the phrase 'blood glucose concentration' rather than just 'sugar' so your answer is precise.
- Structure longer answers as a cycle: stimulus, detector, hormone, target organ, effect, correction.
Try the lesson
The start of the Control of blood glucose concentration: (HT only) Students should be able to explain how glucagon interacts with insulin in a negative feedback cycle to control blood glucose (sugar) levels in the body. lesson, made from checked teaching notes for this specification point.
Have a go first
Which statement best describes how insulin and glucagon interact in a negative feedback cycle to regulate blood glucose?
Key words
Say what each word means before you turn the card.
Insulin
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Glucagon
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Glycogen
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Negative feedback
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See every definition
- Insulin
- Secreted by the pancreas when blood glucose concentration is too high, it increases the uptake of glucose by cells and stimulates the conversion of glucose to glycogen in the liver and muscles.
- Glucagon
- Secreted by the pancreas when blood glucose concentration is too low, it stimulates the liver to convert stored glycogen back into glucose, which is released into the blood.
- Glycogen
- The storage form of glucose in the liver and muscles, converted from glucose by insulin and broken back down into glucose by glucagon.
- Negative feedback
- A cycle in which the two hormones have opposite effects, so each corrects a deviation and restores the set point.
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