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What happens to the flow of blood when heart disease narrows a person's arteries? Create a model to illustrate the answer using straws, disposable cups, and colored water.
| Activity's uses: | Classroom demo or small group exploration |
| Area(s) of science: | Life Science |
| Difficulty level: | 5 |
| Prep time: | <10 minutes |
| Activity time: | <10 minutes |
| Key terms: | health, heart disease, artery, circulatory system, diameter, flow rate, building a model |
To be healthy, every part of the human body needs to be supplied with oxygen and nutrients. The blood's job is to travel through the body's circulatory system (heart, lungs, veins, and arteries) picking up nutrients and oxygen and delivering them to the other parts of the body. The heart acts as a powerful pump that generates the force necessary to move the blood around the circulatory system. When something goes wrong with the body's circulatory system, it can lead to serious health consequences or death.
The most common problem with the circulatory system is coronary heart disease, also called coronary artery disease. Coronary heart disease is caused by the buildup of cholesterol and other material, called plaques, in the arteries. This buildup is known as atherosclerosis. Over time as the plaques grow larger, the arteries, which usually carry oxygenated blood to the heart, become narrower. As the arteries narrow they cannot carry as much blood to the heart. The decrease in oxygenated blood can lead to chest pains and heart attacks. The plaques sometimes become dislodged and form blood clots that block the blood flow—this can also cause heart attacks and strokes.
In this science activity students can model what happens to blood flow when coronary heart disease narrows a person's arteries by comparing the flow of water (blood) through straws (arteries) of different diameters.
This science activity can be used as a starting point for a variety of science and health discussions. Here are a few examples of questions that can be used to start a discussion:
Needed for preparing ahead:
Needed for each demo or small group at the time of the science activity:
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| Figure 1. A few simple household materials are all that are needed to do this fun science activity. |
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| Figure 2. Place play dough, or a similar material, around the straw on the inside of the cup to prevent leaking. Water should only be able to escape through the straw. |
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| Figure 3. Water will flow out of both straws, but at different rates. |
You should see that the cup with the smaller diameter straw empties more slowly. This is because a pipe or straw with a smaller diameter has a slower flow rate. This is also what happens in coronary heart disease. The arteries (straws) become narrower (smaller diameter) due to the build-up of plaques. As the arteries narrow, they carry blood (water) less quickly to the heart.
This science activity can be expanded or modified in a number of ways. Here are a few options:
Sandra Slutz, PhD, Science Buddies
Sponsored by a generous grant from Medtronic
