Model blood glucose regulation
Use insulin and glucagon to model how the body lowers and raises blood glucose to hold it near the setpoint.
- Negative feedback opposes a change: Glucose control is a negative feedback loop, so you must first know that the response works against the change to return a value to its setpoint.
- Gland → hormone → target organ: You need to know a hormone comes from a gland and acts on a target before you can follow insulin and glucagon from the pancreas to the liver and cells.
Prerequisites are inferred: pending teacher review.
Re-learn the skill with worked practice and clear examples.
Blood glucose is held near a setpoint by negative feedback: when it is high the pancreas releases insulin to lower it, and when it is low the pancreas releases glucagon to raise it.
The table shows one student's blood glucose after lunch. Using the trend in the table, which hormone is the pancreas most likely releasing, and what is it doing?
Reviewed| Time after lunch | Blood glucose (mg/dL) |
|---|---|
| 0 min | 95 |
| 30 min | 150 |
| 60 min | 130 |
| 90 min | 105 |
- A.Glucagon, which is raising the blood glucose
- B.Insulin, which is lowering the blood glucose back toward the setpoint
- C.Glucagon, which is lowering the blood glucose
- D.Insulin, which is raising the blood glucose
Show the worked solution ▾
Answer: B. Insulin, which is lowering the blood glucose back toward the setpoint
- Step 1: Read the trend: Glucose rises from 95 to 150 mg/dL after eating, then falls to 130 and 105 over the next hour: after the peak it is going down.
- Step 2: Match the falling trend to a hormone: A falling blood glucose after a meal means the pancreas is releasing insulin, the hormone that lowers blood glucose.
- Step 3: State the action: Insulin makes body cells take up glucose, pulling the level back down toward the setpoint.
Why it's right: After the post-meal peak the values fall (150 → 130 → 105), which matches insulin lowering blood glucose toward the setpoint.
- A: Glucagon raises blood glucose, but the table shows the level falling after the peak.
- C: Glucagon does not lower glucose; it raises it, so this pairing is wrong.
- D: Insulin lowers glucose; it does not raise it, and the table shows a fall, not a rise.
Aligned to Human Body Systems: glucose negative feedback · reading level ~grade 9
- A continuous glucose monitor draws this exact curve: a rise after eating, then a fall as insulin acts: letting a patient and clinician see the negative feedback loop in real time.
Fill these in as you work through the lesson.
- Insulin (lowers blood glucose):
- Glucagon (raises blood glucose):
- Negative feedback (response opposes the change):
- Setpoint (the glucose level the body holds):
- Target organ (where the hormone acts (e.g., liver, body cells)):
When blood glucose rises, the pancreas releases , which makes cells take up glucose and the level. When blood glucose falls, the pancreas releases , which makes the liver release glucose and the level.
- Which hormone is released when blood glucose is high, and what does it do to the level?
- Which hormone is released when blood glucose is low, and what does it do to the level?
- After a meal, blood glucose rises. Trace the two-step response that brings it back toward the setpoint.
A student eats lunch and blood glucose rises above the setpoint. Model the response: name the hormone the pancreas releases, what it makes body cells do, and how the blood glucose then changes.