Higher Tier: opposing responses stabilize glucose
مُقدَّم| English | المعنى |
|---|---|
| glucagon/ˈɡluːkæɡən/ | الجلوكاجون |
| negative feedback/ˈneɡətɪv ˈfiːdbæk/ | التغذية الراجعة السلبية |
What would explain this observation?
- Higher Tier: A system needs a response to low glucose as well as high glucose. The two hormones act in opposite directions but support the same regulated condition.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- When blood glucose is too low, the pancreas releases glucagon 胰高血糖素. This causes glycogen to be converted into glucose, which is released into the blood. When glucose is too high, insulin promotes uptake and storage. Negative feedback 负反馈 means a response opposes the original change and reduces the stimulus for continuing that response.
- glucagon: A pancreatic hormone promoting glucose release when blood glucose is low; negative feedback: A response that opposes the original change in a regulated condition.
Which response fits low blood glucose?
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When glucose is low, glucagon acts on the liver to convert stored glycogen back into glucose, raising blood glucose. Insulin lowers glucose, and glycogen is a store, never a secreted hormone.
Match each technical term to its precise meaning.
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Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Trace two separate pathways: high glucose → insulin → lower glucose, and low glucose → glucagon → higher glucose. Both respond to the regulated variable. Do not say that glucagon and insulin simply cancel each other at all times, or that the system always holds one perfectly unchanging number.
- Interpret supplied feedback diagrams and fictional glucose curves. For each arrow, state whether glucose rises or falls and why. Compare an initial disturbance with the later corrective trend. This is a model-analysis task; no fasting experiment, medication adjustment or blood sampling belongs in classroom practice.
Which two habits make the investigation or model in this case more defensible?
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Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a fictional low-glucose record rises from 3.0 to 4.2 arbitrary units after the stated glucagon response. Increase = 1.2 units, or 40% relative to the starting value. The percentage summarizes the data; it does not establish a clinical target or prove that glycogen stores are unlimited.
A fictional concentration rises from 4 to 5 units. Calculate percentage increase. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A fictional concentration rises from 4 to 5 units. Calculate percentage increase.
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The result is 25 %. Known: concentration rises from 4 to 5 units. Increase = 5 - 4 = 1 unit. Percentage increase = 1/4 x 100 = 25%. The figure summarises the model record, not a clinical target.
Check the conclusion and its limits
- Glucagon is a hormone, glycogen is a stored carbohydrate and glucose is a sugar. Their similar names do not mean they perform the same role. Negative feedback opposes a change; positive feedback would amplify it. The exact response depends on available stores and the stated model.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
Negative feedback amplifies the initial disturbance. This claim is false: Negative feedback OPPOSES the disturbance: a rise triggers a response that lowers the value, pulling it back towards the set point. Amplifying the disturbance is positive feedback.
Higher Tier: opposing responses stabilize glucose: Trace two separate pathways: high glucose → insulin → lower glucose, and low glucose → glucagon → higher glucose. Both respond to the regulated variable. Do not say that glucagon and insulin simply cancel each other at all times, or that the system always holds one perfectly unchanging number.
Negative feedback amplifies the initial disturbance.
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Negative feedback OPPOSES the disturbance: a rise triggers a response that lowers the value, pulling it back towards the set point. Amplifying the disturbance is positive feedback.
A pancreatic hormone promoting glucose release when blood glucose is low: write the technical term.
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glucagon means A pancreatic hormone promoting glucose release when blood glucose is low.