BioEd Online

Teacher Background

In the Scientific Decision-making Teacher’s Guide, students follow the personal stories of Arturo, Brian and Angela, all of whom may be suffering from heart problems brought about by coronary artery disease.

What is CAD? Coronary artery disease, or CAD, develops when the arteries of the heart become damaged or diseased. CAD usually is a result of plaque build-up in the arteries. This condition, called atherosclerosis (Greek for hard paste), begins with inflammation of, and damage to an artery’s innermost layer (endothelium). The cause of this inflammation isn’t understood, but elevated levels of cholesterol in the blood, high blood pressure or smoking may contribute to the initial damage. Inflammation in the artery attracts cholesterol and other substances, which build up just below the inner arterial wall. As we age, this buildup, called plaque, may become thick enough to cause significant blockage, resulting in a condition known as ischemia (reduction in blood flow through the vessel). Cardiac ischemia (or myocardial ischemia) is a reduced flow of blood and oxygen to the heart muscle. It can cause damage to, and a general weakening of the heart muscle, or even total heart failure. Common symptoms included chest pressure or pain, neck or jaw pain, nausea and vomiting. However, it also can be “silent” (showing no symptoms).

Over time, plaque can become unstable and rupture, producing blood clots that may block an artery completely. Such blockage in one of the coronary arteries feeding the heart results in a heart attack, or myocardial infarction (MI). Blockage of an artery that feeds the brain results in a stroke.

Good and Bad Cholesterol

Cholesterol is a kind of lipid (fat) molecule, required by the body to build and maintain membranes. It also is an important precursor molecule for the synthesis of vitamin D and several hormones. All animals manufacture cholesterol. Within the body, about 20–25 percent of cholesterol production occurs in the liver. Cholesterol is stored and transported inside an envelope of lipids and proteins, creating particles called lipoproteins. There are five kinds of lipoproteins, but only two—low density lipoproteins (LDLs) and high density lipoproteins—(HDLs) are measured in a person’s cholesterol score.

For more information about cholesterol, watch the slide show prepared by the American Heart Association (http://watchlearnlive.heart.org/CVML_Player.php?moduleSelect=chlscr).

Objectives and Standards

Materials and Setup

Teacher Materials (see Safety)

• Computer and projector or an interactive white board to display the online animation, What Causes a Heart Attack?

• Small amount (tablespoon) of vegetable shortening in a plastic cup

• Small amount (tablespoon) of vegetable oil in a plastic cup

• Bag of unpopped, plain popcorn kernels

• 3 boxes of small (#1 size) paper clips (15 clips needed per team of students)

• 18 mm x 150 mm glass or plastic test tubes, or six-inch sections of clear tubing (one

• per team)

• Small cups or sandwich bags to hold about 50 kernels of unpopped popcorn

• Nickel- or quarter-size magnets; most refrigerator magnets will work well (one per group)

Materials per Student Team

• One clear 18-mm x 150-mm glass or plastic test tube (or six-inch section of clear

• plastic tubing)

• 15 small (#1 size) paper clips

• Small cup or plastic bag containing about 50 unpopped kernels of popcorn

• One nickel- or quarter-sized magnet

• Masking tape (approximately 12-inch strip)

• Two sheets of notebook paper

Setup

1. Students will work in teams of four.

2. Place all materials in a central location.

Safety

Students should wash their hands with soap and water before and after any science activity, even if wearing gloves. Always follow all district and school laboratory safety procedures.

Procedure and Extensions

A poster-grading rubric is included at the end of this activity (see lesson PDF).

1. In the Scientific Decision-making Teacher’s Guide, one or more characters may have suffered a heart attack. Tell students that they will create a model to learn more about coronary artery disease (CAD) and investigate what happens during a heart attack (myocardial infarction).

2. Show the following video clip (two minutes) on coronary artery disease. The video describes how “plaque” build-up in the arteries leads to heart attack.
   
   What Causes a Heart Attack?
   (http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/causes.html)

3. Ask students, What do you think plaque in the arteries looks like? Allow students time to share their ideas. Tell students that plaque consists of fat, cholesterol, calcium and other substances found in blood; and is waxy in appearance.

4. Then, hold up the cup of vegetable oil and ask students to identify the substance. Tell students that it is cooking oil (a kind of fat or lipid), which typically is extracted from plant seeds (corn, canola, olive, etc.). Next, hold up the shortening, and ask students to identify it. Tell students that shortening can be manufactured from plant oils or it can come from animals (i.e., lard). Pass both containers around the class. Ask, Which of these two kinds of fats is healthier to eat? Tell students that fats that are liquid at room temperature generally are healthier for the cardiovascular system, and can contribute to higher percentages of HDL cholesterol (HDL), which removes cholesterol from the blood stream. Animal fats and fats that are solid at room temperature contribute to higher levels of circulating LDLs. LDL particles are responsible for depositing cholesterol in blood vessels, which can lead to plaque formation.

5. Provide to each student team: one test tube, 15 paper clips, one magnet, one strip of tape (from which they can tear off pieces), and popcorn kernels, as described in the Materials section.

6. Instruct each team to build a model of coronary artery disease from the materials provided. The models should show a narrowing of the passageway (due to plaque), but still allow “red blood cells” to pass through. Accept all reasonable models.

7. On a sheet of notebook paper, have each team create and fill in a table that describes its model. The first column should list all parts of the model (test tube, popcorn kernels, magnet, paper clips). The second column should indicate what is represented by each component. If students need additional direction, tell them that their model should include an artery, red blood cells, plaque and a source of inflammation (something that causes the lining of the artery to become “sticky”).
   
   Note: It is anticipated that most groups will design a model in which the magnet is taped to the side of the tube. One or more paper clips are dropped into the tube (artery) and attracted by the magnet to simulate plaque buildup. Popcorn kernels added to the tube represent red blood cells flowing through the artery.

8. Next, ask each team to build a model of heart attack. This can be accomplished in at least two ways: by creating a build-up of plaque (paper clips) that completely blocks the tube or by making the tube so narrow that red blood cells (popcorn) form a clot that blocks the tube.

9. Have the teams share their models with the class, and explain their designs.

10. Have students return all materials to the original location. Instruct students to use the second sheet of notebook paper to write three things he or she learned from this activity about CAD. Have students submit their answers as they leave the classroom, or complete the assignment as homework.

Extension or Homework

• Make copies of the student page, “Heart Disease Risk Factors,” for each student. Have students read the essay in class or as homework.

• Have students work in teams of 2–3 to create posters on heart-healthy themes, such as describing the process of CAD; risk factors; negative effects of smoking; importance of physical activity, diet and nutrition; or teens and heart disease. Approve each team’s poster idea, and have groups create standard 22-in. x 28-in. posters. Exhibit the posters in school public areas, such as hallways and cafeterias. Consider having team members stand near their posters to answer questions during a lunch period or school-wide heart event, such as a walk-a-thon or blood drive.

Handouts and Downloads