BioEd Online

Teacher Background

The heart and lungs work together to supply all the tissues in the body with oxygen and other materials, and to carry away waste products, such as carbon dioxide. All the cells in our bodies need oxygen to carry out the reactions that release energy. Carbon dioxide, a waste product of this process, is manufactured inside cells when energy is released from sugars and other molecules.

Usually, when parts of the body require more oxygen (as during exercise), the lungs and heart respond by working faster. The lungs also take in more air so that more oxygen can be ab­sorbed into the blood stream and transported to hard-working tissues.

We often measure heart rate by feeling the surge of blood after each heart beat at places on the body where arteries are near the surface of the skin (the wrist, for example). This recurrent surge is known as the pulse. The number of pulses per minute usually is referred to as pulse rate (heart beats per minute). The average pulse rate for a child ranges from 60 and 120 beats per minute.

Objectives and Standards

Concepts

• The functions of the heart and lungs are linked.

• The heart and circulatory system work with the lungs to supply the body with oxygen and to eliminate carbon dioxide.

• The rates at which the heart and lungs work depend on levels of activity.

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Science, Health, and Math Skills

• Observing

• Measuring

• Comparing data

• Drawing conclusions

Materials and Setup

Teacher Materials (see Setup)

• 12 sheets of red construction paper

• 12 sheets of blue construction paper

• paper cutter

Materials per Group of Students

• stopwatch with a second hand, wristwatch, or classroom clock

Materials per Student

• pair of scissors

• one sheet of each color of prepared construction paper

• copy of student sheets

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Setup

1. This investigation works best when the class is divided into two-person teams. The members of each team should take turns monitoring each other. Conduct this activity with the entire class if your students are not able to tell time.

2. Cut the blue and red construction paper (9 in. x 12 in.) in half horizontally to make 9 in. x 6 in. sheets.

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Safety

The safest and most common site to check pulse is on the thumb side of the wrist (radial pulse). Use the middle finger and ring finger together to apply slight pressure at the location shown (see illustration, PDF). This is the pulse site recommended for the general public by the National Heart, Lung, and Blood Institute, National Institutes of Health.

Procedure and Extensions

Time

30–45 minutes to make cut-outs and measure­ments; 30 minutes to graph and summarize results.

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Part 1. Making the cut-outs

1. Give each student one sheet each of blue and red construction paper. Direct students to cut out a set of lungs and a heart from each sheet, using the templates on the “Heart and Lungs Cut-Outs” student sheet. (This can be integrated into a mathematics or art lesson as a symmetry activity.)

2. Have students write their names on their cut-outs.

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Part 2. Gathering data

1. Explain to students that they will be investigating their breathing and heart rates. Make sure they understand that a “rate” is a measure of “how fast” or “how slow” something is happening.

2. Group the students into pairs. Ask them to sit quietly and breathe normally. Have one student count the number of times his/her partner inhales (breathes in) in one minute, and record the results on the “Heart and Lungs Data Sheet.” Older students can time themselves, using a wristwatch or stopwatch. If a student has difficulty observing the breathing of his/her partner, instruct the student being observed to dangle a strip of tissue in front of his/her nose. Have students repeat the measurements at least three times to calculate an average. Then instruct the students to switch jobs.

3. With younger students, conduct this procedure as a whole class activity. You can either time them or direct the timing, while students take turns counting and recording their partners’ breathing rates.

4. Prepare the students to measure their pulse rates (heart beats per minute) by demonstrating the safest way to locate a pulse point (see “Radial Pulse Point,” left sidebar). Give students time to locate their pulse points and practice counting beats.

5. Have students measure their heartbeats by counting the number of times they feel a tiny surge at their pulse points, while their partners time them for 15 seconds. Older students should enter this value on their worksheets and multiply by four to obtain the number of beats per minute. They should take three readings. Younger students may add this value four times to find beats per minute. Have the students switch jobs and repeat the process. Again, with younger students, you  will probably want to direct the activity and measure the time.

6. Next, tell the students that they are going to investigate their breathing and pulse (or heart) rates after physical activity. Ask, What do you think will happen to your heart rate when you exercise? What about your breathing rate? Have one member of each team run in place for one minute and sit down. Have their partners determine their breathing rates again. Older students should repeat this procedure three times. Then, let the students switch jobs and repeat the process. This step should be teacher-directed for younger students.

7. To investigate pulse rate after activity, have the students repeat the process described in steps 3 and 4 after running in place for one minute.

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Part 3. Graphing

1. Draw two large grids for class graphs on chart paper or on the board. Label one grid “Heartbeats per Minute” and the other “Breaths per Minute.” Lines on the vertical axis should be 6 cm apart. Lines on the horizontal axis should be approximately 12 cm apart. Make sure students understand that they were able to quantify their heart rates by counting the tiny surges of blood moving through an artery.

2. Using blue for resting rate and red for active rate, have students write their names and rates on the appropriate cut-outs. Tape students’ cut-outs on the appropriate class graphs OR help each student position his or her cut-outs on the graphs.

3. Ask, Where are most of the blue hearts on the graph? How about the red hearts? Where are the blue lungs? The red lungs? How does exercise affect a person’s breathing rate? Heart rate? Help students notice that heart and breathing rates change together.

Handouts and Downloads