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11. Circulatory and resp

11. Circulatory and resp - Name Section 11 Circulatory and...

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Name______________________________________ Section________________ 11 Circulatory and Respiratory OBJECTIVES 1. Describe the pulmonary circuit versus the systemic circuit 2. Trace the path of blood through the fetal heart Describe where these organs are positioned in relation to each other 3. Trace the path of blood from the heart to and from the placenta in the fetus 4. Compare circulation of blood in a fetus to circulation of blood in an adult 5. Distinguish arteries, veins and capillaries and note the function of each 6. Identify the chambers, valves, and major blood vessels of the human heart and trace the blood flow through the heart. 7. Review “Organs to know” MATERIALS NEEDED Pig dissection materials Sheep heart Heart model PREPARATION Read Biology a Guide to the Natural World Chapter 28 INTRODUCTION Blood must circulate to serve the body. The heart pumps the blood, which moves away from the heart in arteries and arterioles and returns to the heart in venules and veins. Capillaries connect arterioles to venules. Arteries have thick walls that can expand when blood enters under pressure. Blood pressure moves blood in arteries and arterioles. Veins have weak walls and valves that prevent blood from falling back. When skeletal muscles contract, they press against the venules and veins, keeping the blood moving toward the heart. The thin walls of the capillaries allow exchange of materials with the tissue fluid that surrounds the cells. In today's laboratory, you will first learn to trace the path of blood in adult and fetal humans. There are differences in the circulatory patterns of human adults and fetuses. In adults, oxygen enters the blood in the lungs, and nutrient molecules enter the blood at the digestive tract. In fetuses, the lungs and digestive tract do not function. Blood is transported to the placenta, where exchange with the mother's blood takes place and fetal blood receives oxygen and nutrient molecules. You will dissect some of the major arteries and veins in the body of a fetal pig. ACTIVITY I. Path of Blood in an Adult versus a Fetus Your primary goal is to know the path of blood in an adult; therefore, we will begin by learning to trace the path of blood in adults. Your pig is a fetal pig; therefore, we have an opportunity to also learn the path of blood in a fetus. 77
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78 Figure 1 Diagram of the human cardiovascular system. In the pulmonary circuit, the pulmonary arteries take 02-poor blood to the lungs, and the pulmonary veins return 02-rich blood to the heart. In the systemic circuit, the aorta branches into the various arteries that go to all other parts of the body. After blood passes through arterioles, capillaries, and venules, it enters various veins and then the superior and inferior venae cavae, which return it to the heart.
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Path of Blood in Adult Human In adult mammals, the heart is a double pump. The right side of the heart, consisting of two chambers (the right atrium and right ventricle), pumps blood into the pulmonary circuit-that is, to the lungs and back to the heart (Fig. 1). While the blood is in the lungs, it gives up carbon dioxide and
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