Coronal Section Of Heart

The heart is located in a tough, fibrous sac known as the parietal pericardium which has an outer fibrous layer and an inner serous layer. If this sac is opened you can see a space called the pericardial cavity. The heart is in this cavity. The outer surface of the heart is called the visceral pericardium or the epicardium. Inside of this is the main portion of the heart wall called the myocardium (made of cardiac muscle) and the innermost layer of the heart is the endocardium.

Deoxygenated blood enters the right atrium of the heart by three vessels: the superior vena cava, the inferior vena cava and the coronary sinus. The walls of the right atrium are thin-walled as they only have to pump blood to the right ventricle. The blood in the right atrium is in contact with the fossa ovalis which is a thin spot in the interatrial septum. This thin spot is a remnant of a hole in the fetal heart know as the foramen ovale. Blood in the right atrium flows through the cusps of the tricuspid or right atrioventricular valve into the right ventricle. The tricuspid valve is made of the three cusps, the chordae tendineae and the papillary muscles that hold the chordae tendineae to the ventriclc wall. The ventricle wall is lined with trabeculae carneae that act as struts along the edge of the wall. The wall between the vcntricles is known as the interventricular septum.

From the right ventricle, blood passes through the pulmonary semilunar valve and into the pulmonary trunk where the blood goes to the lungs. In the lungs the blood is oxygenated. From the lungs the blood returns to the left atrium of the heart. Blood in the left atrium moves to the left ventricle through the left atrioventricular valve or the biscuspid valve. This valve has two cusps, chordae tendineae and papillary muscles. When the left ventricle contracts, the blood moves through the aortic semilunar valve and into the ascending aorta.

White arrows = oxygen-rich blood Black arrows = oygen-poor blood

To lungs From lungs w.-

White arrows = oxygen-rich blood Black arrows = oygen-poor blood

= arteries

Image Pericardium And Endocardium

Answer Key: a. Pulmonary trunk, b. Pulmonary semilunar valve, c. Left atrium, e. Left atrioventricular valve, f. Aortric semilunar valve, g. Left ventricle, h. Endocardium, i. Epicardium, j. Myocardium, k. Parietal pericardium, I. Fibrous layer, m. Serous layer, n. Interventricular septum, o. Trabeculae carneae, p. Inferior vena cava, q. Papillary muscle, r. Right ventricle, s. Chordae tendineae, t. Right atrioventricular valve, u. Opening of coronary sinus, v. Fossa ovalis, w. Right atrium, x. Superior vena cava, y. Aorta

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