Home > Glucose in balance Lesson Four Today we will… See how homeostasis works to keep the body in balance Learn about the organs and
Glucose in balance
Lesson Four
Today
we will…
Meet the players
Who’s who of diabetes:
Glucose! Many
of the foods we eat are broken down during digestion to this simple
sugar. Glucose is carried to every cell in our body by the blood
stream, where it is used as the source of energy for our bodies.
In our model, the 6-sided glucose sugar
is represented by a round pasta piece.
Glycogen! The
stored form of glucose is called glycogen. Glycogen is made up of many
connected units of glucose.
Please fill out the first section of Student Sheet 4 as you proceed through the next few slides.
Meet the players
Who’s who of diabetes:
Insulin! This hormone is released into the blood when
blood glucose levels are high. It enables glucose to be transported
into the cell in some tissues.
In our model, insulin is represented
by a piece of I-shaped pasta
Glucagon! This hormone is released into the blood when
blood glucose levels are low. It enables glucose to be released
from some tissues back into the blood stream.
In our model, glucagon is represented
by a piece of curvy-shaped pasta
Please fill out the first section of Student Sheet 4 as you proceed through the next few slides.
Meet the players
The body organs:
Pancreas: One of the major players in glucose
homeostasis, the pancreas releases the hormones, insulin and
glucagon, that control blood glucose. The cells in the pancreas
that produce insulin are called β (beta) cells.
Liver: This organ takes up glucose when levels
are high and releases glucose when levels are low. It stores glucose
in chains as glycogen. It is key for glucose regulation.
Meet the players
More body organs:
Muscles: Our muscles are able to take up and store lots
of glucose when insulin is present. More muscles mass means more of
a reservoir for glucose.
Fat cells: Fat cells take up glucose when insulin is present.
Fat cells use glucose to make more fat.
Brain: The brain takes up glucose whenever it needs energy, and doesn’t require insulin. Glucose is the fuel the brain normally uses.
Glucose in balance
All of these systems work together to keep our blood glucose level balanced.
For our model, 3 pasta wheels represent
a balanced amount of blood glucose.
Balanced
Blood Glucose
Balanced
Blood Glucose
Balanced Blood Glucose
Glucose in balance
High blood glucose triggers the pancreas
to release insulin.
High
Blood Glucose
Pancreas releases insulin
Blood vessels carry insulin and glucose to cells
Glucose in balance
Low blood glucose triggers the pancreas
to release glucagon
Low
Blood Glucose
Pancreas releases glucagon
Blood vessels carry glucagon to the body to trigger the release of stored glucose back into the blood.
Glucose in balance
This balancing act happens many times
a day—every time you have a meal or consume a drink with sugar. The
ability of the body to maintain balance and regulate internal conditions
is called homeostasis.
Balanced
Blood Glucose
Please answer question 1, 2 and 3 on Student Sheet 4.
Glucose in balance
How does the pancreas respond?
SCENARIO ONE
You have just eaten a meal of pancakes and maple syrup. What happens?
Glucose in balance
SCENARIO ONE, continued
You have just eaten a meal of pancakes
and maple syrup. What happens?
Please answer question 4 on Student Sheet 4, and wait until your teacher directs you to go on.
Glucose in balance
What happens to the blood glucose level?
How does your pancreas respond?
SCENARIO TWO
You’ve been sitting in school and
haven’t eaten in hours! What happens?
Please answer question 5 on Student Sheet 4, and wait until your teacher directs you to go on.
Glucose in balance
meal
Time in minutes
-60
0
60
120
180
240
Unger, FH. N Engl J Med.
1971; 285:443-9
Please talk about this graph with your partner(s) and draw your predictions on Student Sheet 4 before advancing the slide.
Glucose out of balance
So far, everything we’ve seen has
been the body’s healthy response to glucose.
When our bodies are overweight, especially
around the middle, our insulin receptors become changed and do not bind
insulin as well. This is called insulin resistance
and can lead to the development of type 2 diabetes.
SCENARIO THREE
What happens to blood glucose after
eating a meal when the body becomes insulin resistant?
What does this do to the blood glucose
level? How does the pancreas respond?
Glucose out of balance
Release
5 more insulin in the blood stream.
Put insulin
on all its receptors.
Put
more glucose in liver, muscle and fat.
SCENARIO THREE
Glucose out of balance
Once β cells are damaged, diabetes
becomes a life-long condition that will always require management.
Please answer question 7 on Student
Sheet 4.
What happens?
Insulin resistance
occurs because insulin receptors don’t bind insulin as well. This
causes the pancreas to work hard all the time to release enough insulin
to bring down blood glucose levels.
β cell damage
When the β cells in the pancreas are working hard all the time, they gradually become damaged and cannot make enough insulin to overcome insulin resistance.
Glucose out of balance
Pre-diabetes
At this stage, blood glucose levels
are higher than normal after a meal and at a resting state, but
not high enough to be classified as full-blown type 2 diabetes.
People with pre-diabetes are at increased risk for type 2 diabetes.
Type 2 diabetes
Blood glucose levels
are always high because of high insulin resistance and/or low insulin
levels.
Diabetes
More
than 200 mg/dl
Between
140 mg/dl
and
200 mg/dl
Less than
140 mg/dl
Normal
Blood glucose levels are well-regulated.
Oral Glucose Tolerance Test
(OGTT)
Glucose out of balance
How is diabetes diagnosed?
By measuring blood glucose levels.
Fasting glucose test:
After fasting for at least 12 hours, a person’s blood is drawn and
tested for glucose. A healthy person would have a fasting blood glucose
level of about 80-90 mg/dL.
Oral Glucose Tolerance Test:
After measuring fasting glucose, a person is given a glucose-rich
drink. Blood is then drawn at time intervals to see how that person’s
body is processing the glucose.
A third test, the A1C test, measures how much of a person’s hemoglobin is coated with sugar. Since red blood cells (which carry hemoglobin) turn over every few months, the A1C test gives an average blood sugar level over the past 2-3 months.
Healthy (n=240)
Prediabetes (n=191)
Diabetes (n=100)
0
50
100
150
200
250
300
0
20
40
60
80
100
120
Time (min)
Time (min)
0
20
40
60
80
100
120
0
20
40
60
80
100
120
140
Jensen CC et al: Diabetes 51:2170-2178;
2002
Oral Glucose Tolerance
Test
Please talk about
this graph with your partner(s), and draw your predictions about glucose
levels—the graph on the left—on Student Sheet 4 before advancing
the slide.
Glucose given
Fasting
What happens if…
Using what you’ve learned, predict
what would happen in the following situation:
ONE: The β cells in the pancreas can only produce a very small amount of insulin.
Answer: Without adequate insulin, glucose cannot enter the cells and glucose levels continue to rise in the blood.
Why does this matter?
Excess glucose in the blood binds to proteins, cells and tissues and
they no longer work the way they should. This can lead to:
Please make your prediction on 9a of Student Sheet 4.
What happens if…
Using what you’ve learned, predict
what would happen in the following situation:
TWO: You go from a sedentary lifestyle to one that includes daily exercise.
(Hint: Muscles can take in about five times as much glucose as liver and fat can. Muscles also burn glucose for energy.)
Answer: Regular activity can lower blood glucose levels. Muscles can use their own stored glycogen as energy, as well as taking in glucose from the blood. When glucose levels are low, the liver can also release stored glycogen as glucose for the muscles to use.
Why does this matter?
Exercise lowers blood glucose levels in the following ways:
Please make your prediction on 9b of Student Sheet 4.
What happens if…
Using what you’ve learned, predict
what would happen in the following situation:
THREE: You have been diagnosed with type 2 diabetes and have been prescribed the drug Metformin. (Hint: Metformin acts to lower glucose production in the liver, and increase insulin sensitivity in the muscles.)
Answer: By lowering glucose production in the liver, glucose released by the liver won’t add to already high levels of blood glucose. In addition, the muscles will be able to better utilize the insulin in the blood--sort of like removing some of the sticky notes from the insulin receptors.
Why does this matter?
Treating diabetes often requires medication.
Other drug treatments for type 2 diabetes include:
Please make your prediction on question 9c of Student Sheet 4.
Contributions to type
2 diabetes
Insulin Resistance
in organs and tissues
Decreased Insulin Production
in the pancreas
Elevated Blood Glucose
=
PREDIABETES
TYPE 2 DIABETES
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