Laura's
Lesson
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This lesson was designed for use in a high school Biology class, but the lesson can be simplified for younger students. Lesson Objective After the lesson, the students will be able to describe the anatomy of the cardiovascular system and be able to explain the movement of blood throughout the system, especially the heart. Background Information This lesson can be used as an introduction to the heart and cardiovascular system in general. It would be used, most likely, during the later part of the semester when animal structure and function (all of the body systems) are being taught. Materials needed 1) lesson lecture outline (printed from this
page) *You may not need all of these materials
(depending on the activity/activities you choose). See Activity and Conclusion below. Lesson Outline (print this for use in preparing lecture): Definition of the cardiovascular system (also known as circulatory system): system that transports fluid throughout the body and functionally connects the aqueous environment of the cells to the organs that exchange gases, absorb nutrients, and dispose of wastes. The system includes the heart, blood vessels, and blood. Open vs. Closed Circulatory systems Mammals have a four-chambered heart with two atria and two ventricles. Double circulation ensures vigorous flow of blood as it is pumped a second time after losing pressure in the lungs. The left side handles oxygen-rich blood and the right oxygen-poor blood. The human heart is located just beneath the sternum (breastbone) and is composed of mostly cardiac muscle tissue. The two atria have thin walls and receive blood while the two ventricles have thicker walls and are more powerful than the atria, especially the left ventricle which pumps blood to all body organs. There are four valves in the heart that prevent the back flow of blood. The valves between each atria and ventricle are called atrioventricular (AV) valves, and semilunar (SV) valves or "exit" valves. A stethoscope amplifies the sound of the valves closing. A defect in one or more can cause a heart murmur. The cardiac cycle is the complete sequence of the heart pumping and filling with blood. The contraction, called systole, is when the heart pumps blood. The diastole phase is when the heart relaxes and fills with blood. The volume of blood per minute that the left ventricle pumps to the systemic circuit (organs) is the cardiac output. Arteries rhythmically expand as blood is sent from the ventricles, creating a pulse. Using this, heart rate, the number of times a heart beats per minute, can be be measure. The heart pumps blood into an aorta or arteries. These arteries carry blood away from the heart to arterioles and then to capillaries. In the capillaries, gas exchange occurs, and blood returns to the heart from the capillaries through venules and veins. Tracing the flow of blood through the cardiovascular system:
Beginning with the pulmonary circuit (lung), the right ventricle pumps oxygen-poor blood to the lungs through pulmonary arteries. Gas exchange occurs in capillary beds and then oxygen-rich blood returns to the left atrium heart through pulmonary veins. The blood then flows into the left ventricle where the blood is pumped through the systemic circuit (organs) via the aorta. This sends the oxygen-rich blood through arteries to capillaries to give the body oxygen and pick up carbon dioxide. Within each organ, arteries branch into arterioles which branch into the capillaries which send the blood through venules and then veins (vena cava) which empty into the right atrium. The now oxygen-poor blood flows into the right ventricle and back to the lungs to start the cycle again. Other
related discussion/lecture topics: Activity There are a variety of activities teachers can do with their students concerning the cardiovascular system. Here are my suggestions (choose one): 1: After the lecture, allow students to tour Franklin Institute's Heart Preview. This site provides information, pictures, related topics, movies, and more. Teachers could ask students to listen to a heart murmur, create a menu for a diet that keeps a heart healthy, read about blood types, look at movies of heart surgery, etc. This gives students or groups of students a choice of a project related to the cardiovascular system and promotes technology skills. There is also a great activity under LEARN for younger students that involves making an early stethoscope.
2: After
the lecture, allow students to work in pairs and measure blood pressure.
The typical blood pressure for adults (young) is 120/70. The first
number is the systolic pressure, and the second is the diastolic
pressure. Using a sphygmomanometer, wrap the cuff around the upper arm
and inflate until above 120. Listening with a stethoscope, gradually
deflate until the blood begins to flow through the arm (heard with the
stethoscope). At the point of hearing the blood, record the systolic
pressure. Continue loosening the cuff until the sound disappears--this
is the diastolic pressure. Conclusion Complete the activity at LessonPlanz.com as a class. In doing the activity, students will follow the flow of blood throughout the cardiovascular system. This activity connects all of the concepts and anatomy learned in lecture, the objective of the lesson, while provided a fun summary of the information.
If time does not permit such an
activity, the teacher can ask students to write a brief journal tracing the
flow of blood through the system. This is also great review for a test
or quiz. Evaluation Evaluation should include the teacher making anecdotal (mental) notes of each student's participation and comprehension during the activity and conclusion. In addition, being a high school class, the teacher will most like give a test over the material. Again, the conclusion can be used as a review.
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