FIGURE 5 4 Aortic valve With the three valve leaflets open blood flows freely

Figure 5 4 aortic valve with the three valve leaflets

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FIGURE 5-4 Aortic valve. With the three valve leaflets open, blood flows freely through the valve. When the valve leaflets close, their edges seal tightly against one another, preventing the backflow of blood. Source : Pearson Education Leaflets open Leaflets closed FIGURE 5-5 Layers and membranes of the heart. The endocardium lines the four chambers and valves inside the heart. The myocardium is the muscular layer of the heart. The pericardium is the membrane around the pericardial sac that contains pericardial fluid. Source : Pearson Education Parietal pericardium Pericardial fluid Visceral pericardium (epicardium) Myocardium Coronary artery and vein Endocardium Pronunciation/Word Parts myocardium ( MY -oh-KAR-dee-um) my/o- muscle cardi/o- heart -um period of time; structure myocardial ( MY -oh-KAR-dee-al) my/o- muscle cardi/o- heart -al pertaining to chordae tendineae (KOR-dee TEN-dih-nee-ee)
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Chapter 5 Cardiology 199 The myocardium contracts in a coordinated way to pump blood. First the myocar- dium around the two atria contracts, forcing blood into the two ventricles. Then the myocardium around the two ventricles contracts. The blood in the right ventricle goes into the pulmonary trunk and the pulmonary arteries (that go to the lungs). The blood in the left ventricle goes into the aorta (that goes to the entire body). The myocardium is thickest on the left side of the heart because it is the left ventricle that must work the hardest to pump blood to the entire body. Thoracic Cavity and Mediastinum The thoracic cavity contains the lungs and the mediastinum , an irregularly shaped central area between the lungs (see Figure 5-6 ). The mediastinum contains the heart and parts of the great vessels (aorta, superior vena cava, inferior vena cava, pulmonary arteries and veins), as well as the thymus, trachea, and the esophagus. The word cardiothoracic reflects the close relationship between the heart and the thoracic cavity. endocardium Innermost layer that lines the atria, ventricles, and heart valves. ( Note : This layer also extends into the blood vessels where it is known as the endothelium or intima .) myocardium Muscular layer of the heart pericardium Outermost layer. This membrane surrounds the heart as the pericardial sac and secretes pericardial fluid. The pericardial sac is U-shaped, and the heart is within the U. The part of the membrane that is next to the surface of the heart is the visceral pericardium or epicardium because it is upon the heart. The part that is the outer wall of the pericardial sac is the parietal pericardium . Pericardial fluid is a slippery, watery fluid that allows the two membranes to slide past each other as the heart contracts and relaxes. Table 5–1 Layers and Membranes of the Heart cardiothoracic ( KAR -dee- OH -thor-AS-ik) cardi/o- heart thorac/o- chest; thorax -ic pertaining to mediastinum ( MEE -dee-ah-STY-num) mediastinal ( MEE -dee-ah-STY-nal) mediastin/o- mediastinum -al pertaining to parietal (pah-RY-eh-tal) pariet/o- wall of a cavity -al pertaining to thoracic (thor-AS-ik) thorac/o- chest; thorax -ic
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  • Summer '19
  • Adam Thompson
  • right ventricle, left ventricle, right atrium, left atrium, ascending aorta

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