Download The Role of Insulin in Maintaining Blood Glucose

THE ROLE OF INSULIN IN MAINTAINING BLOOD GLUCOSE HOMEOSTASIS:
A LESSON PLAN USED IN CONJUNCTION WITH THE VIDEO “HILLBILLY HYPOGLYCEMIA”
Alexis Wren, Michael Ridlehoover, Zachary Minter, Jennifer Cannon
Department of Biological Sciences
Georgia Regents University
Augusta, GA 30904
The video, “Hillbilly Hypoglycemia,” explains the physiological significance of insulin in blood sugar
homeostasis. It begins with the backwoods adventure of Cletus and his diabetic friend Earl, who
unexpectedly loses consciousness. Upon arrival at the emergency room, Dr. Wren is able to explain in
simple terms to Cletus how insulin controls glucose uptake into the cells, thus controlling blood glucose
levels. Included in the video is a demonstration that shows insulin binding to the insulin receptors and
the recruitment of glucose transporters to allow glucose entry into the cell. The video also defines
hyperglycemia and hypoglycemia and explains how these opposing conditions can occur in diabetics.
The video can be found at http://www.youtube.com/watch?v=C1EEgiX4Av8.
Students often know that there is a relationship between diabetes, blood sugar, and insulin, but they
have difficulty in understanding how insulin controls blood sugar levels. To aid students in
comprehending the mechanism by which insulin regulates glucose transport into cells, this video could
be used in conjunction with a lesson designed around reenactment of the demonstration shown in the
video. A suggested lesson plan follows.
Objective: Students will be able to demonstrate the effect of insulin and how glucose transports into the
cell, in a fun and interactive way.
Prerequisites: Students should have a clear understanding of cell structure and function, homeostasis,
and hormonal signaling.
Materials:
-Large, open room (a large classroom would work)
-12 or more students
-8 or more chairs (can substitute with desks if in a classroom)
-white, black, green, and blue shirts for all students (hats or other materials to differentiate may
be substituted for shirts)
-Ratio (approximate): 1 white: 1 black: 2 green: 1 blue
Lesson Procedure: To begin the lesson, review the definition of homeostasis. Ask students the
importance of maintaining relatively constant blood glucose levels. Tell students that one mechanism
for regulating blood glucose homeostasis is the hormone insulin. This would be a good place to review
the definition of hormone and receptor. Have students sketch a cell and designate where insulin
receptors would be found. Next, tell students that you are going to recreate their sketches in the class
using chairs and each other. Arrange the chairs in a large, tight circle. This is the cell membrane.
Designate students as insulin (white shirts), insulin receptors (black shirts), glucose transporters (blue
shirts), or glucose (green shirts). Have the insulin receptor students position themselves randomly
between the chairs, as part of the cell membrane. Have the glucose transporters positioned in the
inside of the cell.
Reiterate to the students that glucose is always in the blood stream and that the body tries to maintain
levels within a defined range. To demonstrate this, allow 1-2 glucose students to walk quickly around
the cell. Explain that the glucose cannot get into the cell without the help of the glucose transporters.
Have the glucose try to get in the cell. They cannot get in because they are blocked by the cell
membrane (chairs).
Explain that after a meal, glucose concentration increases in the blood. Have all of the glucose students
walk quickly around the cell. When glucose concentration rises, insulin is released by the pancreas. The
insulin binds to the insulin receptors in the cell membrane. Have all of the insulin students walk out and
“bind” with an insulin receptor. Have the insulin receptor and insulin students who are “bound” form a
bridge or gate that opens up the inside of the cell to the outside of the cell.
When insulin binds to the receptor, the glucose transporters are allowed to come to the surface of the
cell membrane and “pull” glucose molecules in. Allow the glucose transporter students to get under the
bridge created by the insulin and insulin receptor students. The glucose transporter students can pull
glucose students into the cell as they pass by. Continue to allow them to pull in students until there are
only 1-2 glucose molecules left outside of the cell. Explain to the students that once glucose levels are
back to normal, the insulin levels decline so that the insulin receptors are deactivated and the glucose
transporters are no longer recruited to the cell membrane. At this point, have the students watch the
video, “Hillbilly Hypoglycemia.”
After the video, have the students list the events that occur after consumption of a large meal in terms
of insulin and glucose. Make sure they understand that it is insulin binding to its receptor that allows
the recruitment of glucose transporters to the cell membrane, and it is the glucose transporters that
remove glucose from the bloodstream into the cell. To ensure that students have a clear comprehension
of the process, have them apply their knowledge to different situations. Explain that Type I diabetics do
not produce insulin. You may have the students act out what happens in these individuals or just explain
what happens. Type II diabetics have developed insulin resistance, often meaning their insulin receptors
are no longer present on the cell surface or are no longer working properly. Again, have students act out
this scenario.