Module 2 Lesson 6 - 3
Lesson 6 — The Pancreas
Pancreatic Hormones
Read pages 456 - 457
As with calcitonin and PTH produced by the thyroid and parathyroid glands, insulin and glucagon produced by the pancreas are antagonistic hormones. They responsible for regulating blood glucose.
Through its mechanisms, insulin lowers blood glucose levels and glucagon, through its mechanisms, raises levels of blood glucose. Together, these hormones maintain homeostasis by way of negative feedback. Restoration to a range of normal glucose levels
acts to control hormone secretion.
Read pages 456 to 457 of your textbook, which describes how pancreatic hormones maintain blood glucose levels. A good summary of negative feedback is given in Figure 13.25 on page 457 of the textbook.
Watch and Listen
Visually explore the same concepts by watching the following segment of Biologix-11 on Blood Glucose Levels (4 minutes).
©Alberta Education. The Pancreas: Regulating Blood Glucose Levels (3:43 - 8:08); Series 11. LearnAlberta.ca
Try This
Now that you know about blood glucose regulation by insulin and glucagon, complete the following written-response question.
Use the following information to answer the following question.
Blood glucose concentrations of one individual were monitored for several hours. The following data was collected. The blood glucose level of a healthy person is approximately 90 mg/100 mL.
| Time | Blood Glucose Levels (mg/100 mL) |
|---|---|
| 7:00 a.m. |
80
|
| 8:00 a.m. |
120
|
| 9:00 a.m. |
90
|
| 10:00 a.m. |
75
|
| 11:00 a.m. |
100
|
| 12:00 noon |
80
|
| 1:00 p.m. |
125
|
| 2:00 p.m. |
100
|
| 3:00 p.m. |
90
|
-
Plot this data on the grid below. Draw a curved line through the points and label your graph appropriately. Draw a horizontal dotted line showing the approximate blood glucose level of a healthy individual. (6 marks)
-
On the graph, indicate with an arrow two places where a blood test would reveal high levels of insulin. Explain why insulin would be at high levels at these times. (4 marks)
-
Predict what would happen to this person's blood glucose levels if he or she worked out at the gym from 9:00 a.m. to 10:00 a.m. How would his or her body respond with respect to blood glucose levels? (2 marks)
- The graph shows that this person's glucose levels fluctuate throughout the day. Is this person healthy or does he or she have a malfunctioning pancreas? Explain your answer. (3 marks)
Self-Check Answers
- The graph should look similar to the one shown below.
The marks will be assigned as follows.
1 mark for the title - including the manipulated and responding variable
1 mark for correct labels and units on the x-axis
1 mark for correct labels and units on the y-axis
1 mark for using suitable scales for each axis - graph should use the whole grid
1 mark for drawing a smooth curved line through the points rather than a jagged line
1 mark for showing the approximate blood glucose level of a healthy individual
-
First place that insulin will be high - a time selected somewhere between 7:00 a.m. and 8:00 a.m. and marked on the graph with an arrow (1 mark)
This is a time shortly after breakfast. The absorption of glucose from the meal raises blood glucose levels and the high glucose levels stimulate the beta cells in the pancreas to release insulin to lower blood glucose levels to the normal range. (1 mark for the explanation)
Second place that insulin will be high - a time selected somewhere between 12:00 noon and 1:00 p.m. and marked on the graph with an arrow (1 mark)
This is a time shortly after lunch. Absorption of glucose from the meal raises blood glucose levels and the high glucose levels stimulate the beta cells in the pancreas to release insulin to lower blood glucose levels to the normal range. (1 mark for explanation). (1 mark for the explanation)
Because the explanation is the similar for both places, award two marks if the student explained the reason correctly.
(Total 4 marks)
-
The muscle cells use increased amounts of glucose for cellular respiration. (1 mark)
As a result, blood glucose levels start to drop. (1 mark)
In response to lower blood glucose levels, the alpha cells in the pancreas secrete glucagon into the bloodstream.
Glucagon stimulates the liver to convert glycogen into glucose, which is released into the blood to raise blood glucose levels. (1 mark)
(Total 3 marks)
-
This individual is healthy according to the levels of blood glucose indicated. (1 mark)
If 90 mg/100 mL is considered to be a normal set value, then small fluctuations around the set value are to be expected. (1 mark)
Only if the fluctuations are large and stay above or below the set value continually is the person considered to have pancreatic dysfunction. (1 mark)
(Total 3 marks)