This activity page will offer:
lab experience during which students explore the relationship
between pressure and vessel diameter
A model that represents how elevated blood pressure may
affect weakened vessels
An open-ended design challenge in which students engineer
their own remote repair device
Clean drinking straws
plastic soda container
1- Vessel Flow
this program, you learned how changes in the diameter of a
vessel can affect the flow of moving blood. Vessels that become
obstructed or constricted offer more resistance to the movement
of fluid. This may cause blood to backup or the pressure to
build to damaging levels. In this activity, you'll explore
models that represent normal and constricted blood vessels.
You'll also observe how a build-up of pressure may affect
a weakened vessel wall.
Work with a partner. Fill a plastic container 2/3 full of
a clean straw about halfway down the container's length
measured from the bottom of the vessel to its top. Although
the exact depth isn't critical, it is important that you
remember this depth and restrict it as a controlled variable.
Therefore, use a piece of tape to mark this depth on the
outside of the container. Make sure the tape is even with
the lower edge of the straw.
team member blows into the straw with a steady air stream
that produces about a continual stream of bubbles. Describe
the blowing effort needed to produce this steady, but non-violent
stream of bubbles.
pack the end of a second straw with a bean-sized lump of
a paperclip and use it to poke a small hole through the
this straw to the depth marked in step 2. Again, blow a
steady air stream into the straw. How does the effort compare
to when the passageway was larger? Does the appearance of
the bubble stream change? How?Don't
throw these straws away. You'll reuse them in Part 2.
roles with your partner. Make sure to use two new straws
when you repeat the above steps.
What did the clay represent?
happens when the clay constricts the flow of air?
did you compensate to maintain the steady bubble rate?
was the depth of the straw marked and kept constant throughout
2 - Wall Weakness
excessive pressure, blood vessels can burst open with fatal
consequences. Often, this rip occurs in a region of the vessel
that has been weakened or damaged. In this next activity,
you'll model how an increase of pressure can stress a vessel
beyond its limits. Before you start on the hands-on part of
this next activity, let's engage some of your minds-on skills.
From what you have learned both in and out of the classroom,
answer the questions below.
What physical properties are essential in materials used
to build both water pipes and organic vessels?
have been asked to build a water pipe. Rate the following
materials based upon their ability to withstand water pressure.
wood, plastic, copper, modeling clay,
you were patching a bicycle tire. How would the composition
of the patch material affect the long-term success of your
sure that all straws to be used in this activity are completely
dry. Both partners should use scissors to make a "v" snip
about 2/3 of the way up the length of the two straws you
each used in the previous activity. The hole should be about
the same size in all straws.
four pea-sized lumps of clay and flatten each one out into
a thin, rectangular clay patch that is large enough to form
a "collar" around the straw.
the patch on a flat surface. Position the straw's hole above
the middle of the patch. Lightly press the straw against
the patch and roll it so that the patch forms a complete
"collar" around that section of the straw. Make sure that
the clay sticks to the straw's surface and that the seal
has no observable leaks.
First, test the straw that is unobstructed (no inner plug).
Take turns inserting your straws into the water-filled container.
Make sure that the patch remains above the water level.
Start blowing. What happens?
take turns testing the obstructed straw. Insert the clay-plugged
end into the water filled container. Keep the patch above
the water level. Start blowing. What happens?
Analysis of Your Model
the following questions and discuss them based on the above
In your model, what does the plastic straw represent?
does the flattened clay seal represent?
can the experience above be applied to the obstruction/constriction
of blood vessels?
does the seal rupture when air is blown through the plugged
Why did surgeons in the television program position the pressure
release hole within the heart? Wouldn't it be safer and easier
to locate (and later repair) this hole if it was positioned
outside the heart?
seen the trick before. A magician taps a wand and presto!
Flowers seem to materialize out of thin air. In this segment,
Alan commented that loading the metal seal reminded him of
the magic flower trick he performed as a child. With what
you now know about the seal's action, can you figure out what
Alan meant? If so, draw a blueprint for a both the magic wand
and the appearing flowers. The blueprint should illustrate
and explain how a bouquet can appear almost instantly from
the tip of the wand.
this show, you observed an invention that is used to close
a small by-pass opening in a human vessel. His device used
a spring-loaded seal that opened and attached to all sides
of the opening, almost completely filling the hole. When the
delivery line was removed, the seal remained firmly in place
offering a substrate on which living cells would soon grow
and fill the hole entirely.
a house has a water hose buried in its front yard and it suddenly
ruptures. Digging up the hose up to repair it will be extremely
costly. You have been asked to create a remote sealing device
that was used to plug the hole. What type of seal would you
create? How would this be loaded into a buried hose? What
action would trigger the patch to open and plug the leak?
how holes in garden hoses and water pipes are plugged. Decide
on a sealing method. T hen, create a blueprint for your remote
delivery system. Share it with other class members and invite
suggestions to improve the design. With your instructor's
approval, construct this device. Test your apparatus in a
section of garden hose or within a piece of 1" thick plastic
tubing, and evaluate its effectiveness. Keep improving your
design until you've created the best remote sealing device.
and Heart Disease
General information on the heart and its disorders from the
American Heart Association
Children's Heart Institute
This site offers some great visuals using a building floor
plan analogy to illustrate the movement of blood in various
activities in this guide were contributed by Michael DiSpezio,
a Massachusetts-based science writer and author of "Critical
Thinking Puzzles" and "Awesome Experiments in Light & Sound"
(Sterling Publishing Co., NY).
Advisors for this guide
Corrine Lowen, Science Department, Wayland Public Schools,
Suzanne Panico, Science Department, Fenway High School, Boston,