Feedback and internal conditions
הוצג| English | משמעות |
|---|---|
| homeostasis/ˌhəʊmiːəˈstɑːsiz/ | בית-צורה |
| negative feedback/ˈneɡətɪv ˈfiːdbæk/ | משוב שלילי |
What would explain this observation?
- Blood glucose rises after a meal, but usually does not keep rising indefinitely. A control system responds to the change in internal conditions.
Build the model
- Homeostasis 稳态 maintains internal conditions within suitable limits.
- Receptors detect changes, coordination centres process information, and effectors respond.
- Negative feedback 负反馈 opposes the original change.
- homeostasis: Maintenance of suitable internal conditions.
- negative feedback: A response opposing the original change.
Which response opposes a rise in blood glucose?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Insulin lowers blood glucose by promoting uptake and storage of glucose, opposing the rise - this is negative feedback. Releasing glucose from glycogen would raise glucose further, and stopping respiration would harm cells rather than regulate glucose.
Match each technical term to its precise meaning.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- When blood glucose is high, insulin helps increase glucose uptake and storage as glycogen.
- When it is low, glucagon supports release of glucose from stores.
- These responses are coordinated, not identical effects of two hormones.
In the lab: Interpret a time graph by identifying the initial disturbance, the response and the return toward the normal range. Mark the delay before a response. Do not assume a graph shows an instantaneous correction.
Which two habits make the investigation or model in this case more defensible?
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
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
- Known: glucose changes from 5.0 to 7.0 arbitrary concentration units.
- Increase = final - initial.
- Increase = 7.0 - 5.0 = 2.0 units.
- Percentage increase = 2.0/5.0 × 100 = 40%.
- The numerical change is evidence of a disturbance, not a diagnosis on its own.
Your turn: A value rises from 4.0 to 5.0. Calculate the percentage increase.
A value rises from 4.0 to 5.0. Calculate the percentage increase.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
The result is 25 %. Known: the value rises from 4.0 to 5.0 units. Increase = final - initial = 5.0 - 4.0 = 1.0 unit. Use percentage increase = increase / initial x 100. Percentage increase = 1.0/4.0 x 100 = 25%. The change is evidence of a disturbance, not a diagnosis by itself.
Check the conclusion and its limits
- Negative feedback does not mean the response is harmful or the measured value becomes negative.
- Diabetes has different mechanisms; do not treat every case as a failure to make insulin.
Not true: Negative feedback always makes the measured value negative. Negative feedback means the response opposes the change - it pushes the value back towards the set point. "Negative" describes the direction of correction, not a harmful effect or a negative measurement.
- Homeostasis maintains internal conditions within suitable limits.
- When blood glucose is high, insulin helps increase glucose uptake and storage as glycogen.
- Watch for: negative feedback does not mean the response is harmful or the measured value becomes negative.
Negative feedback means the response opposes the change - it pushes the value back towards the set point. "Negative" describes the direction of correction, not a harmful effect or a negative measurement.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
True. Negative feedback means the response opposes the change - it pushes the value back towards the set point. "Negative" describes the direction of correction, not a harmful effect or a negative measurement.
Maintenance of suitable internal conditions: write the technical term.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
homeostasis means Maintenance of suitable internal conditions.