PEER Module Test Template s1

Veterinarians’ Black Bag Activity Plan The Circulatory System

Lesson Summary: This activity is to teach students more about the heart and how the heart pumps blood through the body. If available, the students can observe the Daphnia organism and see the heart beat and blood flow. The students are able to listen to their own and each other’s hearts and identify important sounds. The students will fill out the corresponding worksheet to guide them in this process.

Subject: Science: Unifying Concepts and Processes, Science as Inquiry, Life Science

Grade Level:  Target Grade: 8  Upper Bound: 8  Lower Bound: 6

Time Required: One class period.

Materials:  vial of live Daphnia (These may be purchased at specialty tropical fish stores or ordered online from websites such as http://www.lfscultures.com/cultures.html ) o If you do not have a microscope, but would like to see the Daphnia heart, please visit http://ebiomedia.com/gall/classics/Daphnia/daphnia_behave2.html  pipette or dropper  slide  light microscope  cold water  hot water  thermometer  Stethoscopes (these may be purchased at any medical supply or nursing supply store)  Timer (stopwatch)  Circulatory System worksheet

Lesson Plan:

Observation of the Heart of Daphnia (this can also be done as a teacher demonstration with the students taking turns looking in the microscope) or it may be viewed online if a microscope is not available (although you will not be able to alter the temperature)  Obtain a vial of Daphnia. Measure and record the temperature of the water in the vial.  Place a drop of the Daphnia onto a slide, and put on a cover slip. Place the slide on the microscope, under the scanning objective.  Focus on the reddish pulsating object in the thorax of the Daphnia. This is the heart. Increase the magnification as high as possible, and observe the flow of blood. Record the number of heartbeats in a minute.

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 Add a drop of cold water to the slide. Record the temperature of the water used. Then observe to see if the heart rate changes. Observe for eight minutes, recording the heart rate every two minutes.  Add a drop of warm water to the slide, preferable warmer than room temperature but not boiling. Record the temperature of the water used, then repeat the observation of the heart rate under the microscope.  Based on your observations, write down what you infer about the effects of temperature on heart rate.

Identifying Heart Sounds  Students should be paired with other students of the same gender.  Obtain a stethoscope and wipe the ear pieces with an alcohol swab. Place the ear pieces in the ears.  Place the bell of the stethoscope on your subject's chest, and listen for the heart sounds.  Identify the first sound, which signals ventricular contraction or systole. How long is the interval between the first sound and the second sound, which signals ventricular relaxation or diastole?  Time the interval between the second sound and the next first sound. After five of these intervals, estimate the average time the heart is at rest in a minute, and the average time the heart is in contraction in a single minute.

Assessment: Grade the student worksheet for completeness. There are not necessarily right or wrong answers, but the students need to grasp the major concepts associated with these activities.

Background & Concepts for Teachers:  Blood pressure: The force of blood exerted on the inside walls of blood vessels. Blood pressure is expressed as a ratio (eg 120/80) The first number is the systolic pressure, or the pressure when the heart pushed blood out into the arteries. This is when the heart contracts. The second number is the diastolic pressure, or the pressure when the heart rests. The first heart sound is loudest because it is associated with contraction and the forceful movement of blood through the circulatory system. The second heart sound is associated with relaxation and the passive movement of blood into the heart.  Daphnia: They are small, mostly crustaceans, between 0.2 and 5 mm in length. Daphnia are one of the several small aquatic crustaceans commonly called water fleas because of their saltatory or jumping swimming style (although fleas are only very distantly related). They live in various aquatic environments ranging from acidic swamps to lakes, ponds, streams and rivers. Even under relatively low power, it is possible to observe blood being pumped around the circulatory system by the simple heart. The heart is at the top of the back, just behind the head. Their average heart rate is approximately 180 bpm under normal conditions. Daphnia are tolerant of being observed live under a cover slip and appear to suffer no harm when returned to open water. Daphnia are cold-blooded animals, and they do not thermoregulate. This means that their body temperature is the same as the water they are floating in. The chemical reactions that occur in the cells of Daphnia are dependent on certain enzymes, or proteins, to help the reactions proceed. As the temperature of the water is increased, the metabolism of the Daphnia increased as well, because chemical reactions occur faster at higher temperatures. This means that the

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heart rate will speed up in order to provide oxygen to the cells as the metabolism increases. The reverse occurs as the organism is placed into a cooler environment.

References:  http://www.accessexcellence.org/AE/AEC/CC/heart_activities.html  http://www.sciencefriday.com/kids/sfkc20030912-1.html http://www.fi.edu/biosci/vessels/veins.html

Additional Resources For more cardiology fun visit PBS NOVA’s website, Electric Heart at http://www.pbs.org/wgbh/nova/eheart/. Students can read an interview from one of the pioneers of heart surgery, learn cool facts about keeping your heart healthy, and practice their own heart replacement surgery.

TEKS: Health Education 6.2 (A) Analyze the relationships among the body systems 7-8.6 (A) Relate physical and social environmental factors to health Science 6.12 (A) Identify responses in organisms to internal stimuli 6.12 (C) Identify components of an ecosystem to which organisms respond 7.5 (A) Describe how systems may reach an equilibrium 7.9 (A) Identify the systems and functions of the human organism 8.6 (A) Describe interactions among systems in the human organism 8.6 (B) Identify feedback mechanisms that maintain a system’s equilibrium

A product of the Partnership for Environmental Education and Rural Health at Texas A&M University