Sheila M. Martin-Corbin
Students will respond to pre-assessment questions on the cardio-vascular system to assess their prior knowledge of the subject matter and to clarify any misconceptions.
(See Lesson 1)
This will be followed by class discussion on pre-assessment questions and feed-back noted on chalk-board. Students will record corrected responses in their notebooks.
In small groups students will brain-storm the impact sedentary jobs have on one’s physical health and what things could be done to promote a healthy heart. The recorder from each group will share their findings with the whole class. Students may respond by saying that soda and coffee machines on the job is responsible for obesity. Too much sugar intake and an unhealthy diet and no physical exercise can lead to heart attacks.
The next three lessons will be devoted to exploring and learning about the anatomy and physiology of the cardiovascular system. Varied resources will be implemented, including descriptive charts, models, CD-ROM, interactive websites, such as www.interactivephysiology.com with tours and animation about cardio-vascular anatomy and physiology. Students will explore these websites individually and in small teams. After this guided research, students will complete a graphic organizer illustrating blood flow in the heart and will use this information to produce a schematic, labeled drawing of the anatomy of the heart and the pathway of blood circulation. Students may use red and blue markers or crayons to highlight the flow of deoxygenated and oxygenated blood during pulmonary and systemic circulation.
Subsequent lessons will include the dissection of a sheep’s heart. Dissection of a sheep’s heart is valuable because it is similar in size and structure to the human heart. Also it allows students to view structures in a way not possible with models and diagrams. Students will examine the external surface of the heart, identify the major structures of the heart involved with blood circulation, describe what each structure looks like and the role each play in blood circulation. (See vocabulary below).
Students will view microscope slides showing cross sections of an artery, vein and capillaries. A comparison of these blood vessels will be described in chart form by students. (See vocabulary below).
Students will listen to his or her partner’s heart sounds with an ordinary stethoscope, determine body sites where the pulse is most easily palpated, and then accurately determine each other’s blood pressure using a sphygmomanometer, with guidance from the school nurse. .At the end of this activity, students will be able to discriminate diastolic from systolic pressure. Students will be provided with an article on ‘heart physiology and blood pressure’ as an extension of this activity for reinforcement and further understanding of the concepts learned.
Changes in blood pressure and pulse during and after exercise provide a good yardstick for measuring overall cardiovascular fitness. Different kinds of activity affect blood pressure differently. Although blood pressure goes up during any kind of exercise, the changes brought on by exercise vary according to whether the exercise is aerobic or 99isometric. Aerobic exercise involves large muscle groups engaged in rhythmic, repeated movements ex. jogging. Isometric exercise is defined as a sustained contraction of a muscle group ex. weight lifting. Aerobic activities depend mainly on energy derived from consuming oxygen. Thus, they increase the body’s need for oxygen. Because blood delivers oxygen to the body, aerobic activity challenges the heart and circulatory system to meet this increased need. Systolic blood pressure rises progressively, while diastolic blood pressure stays the same or decreases slightly. Pulse rate rises, and blood flow to the muscles increases. Thus, aerobic exercise exerts a volume load on the heart. One way to detect changes in cardiovascular activity and oxygen consumption is to measure your pulse rate before, during and after an activity. Aerobic exercise will increase one’s pulse over the course of the exercise, and the more energy demanding, the more one’s pulse will increase. When one stops exercising, his or her pulse rate does not immediately return to normal. Instead, it gradually returns to its resting level. The greater one’s fitness level, the sooner one’s pulse rate will fall.
Students will work in small groups to investigate cardiovascular responses to changes in posture --heart rate sitting quietly, heart rate immediately on standing, heart rate after standing for three minutes and heart rate holding his or her breath. As a result, the heart rate will increase more rapidly by holding one’s breath compared to standing or sitting as the heart is pumping faster to supply and compensate for the oxygen which is cut off. One student in each group will act as the subject, another as the examiner and the third student will act as timer and record data.
Extended activities involving parents and/or siblings will include students taking their heart rates and graphing the data based on their ages. Students can then show the correlation between heart rate and body mass. Students will also be required to keep a log for one week on their heart rate in the morning and at night and then construct a graph to show their results. Blood pressure can vary widely. It can rise when one exercises, or
it may become low when one is asleep. However, blood pressure is a little on the high side when a person wakes up in the morning. It remains at these levels during the daytime and decreases during sleep. Therefore, a single reading should not be used to make a diagnosis of high blood pressure.
Students will research cardiovascular diseases and then create a pamphlet or a poster to educate the public about what are some possible solutions to decrease the number of heart attacks and disorders. Examples include modifying school cafeteria menus, banning cigarette smoking in restaurants and public places, banning of the use of Trans fat in restaurants and increase and availability of recreational areas such as gyms, and parks.
I have designed this unit to accommodate the different learning styles and abilities of my students. Students who have difficulty with writing and or verbal expression have the opportunity to demonstrate their artistic talent with their schematic drawing, creating a brochure, inquiry lab. activities and dissection of the sheep’s heart. Opportunities for developing and improving their writing and verbal skills are offered in this unit as mastering these skills are crucial for students to become successful.
