BIOL1010 Fall21 Lab 9 - The Heart and General Circulation

Lab Exercise 9 The Heart and General Circulation Text reference: This lab exercise is designed as an introduction to the circulatory system. To observe the heart, the major organ of this system, we will continue working with the fetal pig. The thoracic cavity will have to be opened. A mid-ventral cut from the diaphragm toward the throat should be made. Cut carefully through the sternum and gently pull the rib cage apart. Remove the pericardial sac which surrounds the heart. Identify the four chambers of the heart: the right atrium, right ventricle, left atrium, and left ventricle. The atria are flattened, scalloped structures atop the conical, muscular ventricles. The coronary artery approximately shows the division of the ventricles on the ventral surface. Two large veins enter the right atrium from the body: the anterior and posterior vena cava veins. Locate these. They should appear blue. Veins always carry blood toward the heart. The thick-walled pulmonary trunk (artery) exits the anterior part of the heart (as blood leaves the right ventricle). Further along than you will be able to see, it branches into the pulmonary arteries that carry blood to the lungs. Locate the pulmonary trunk. Dorsal to it a small portion of the arch of the aorta can be seen. This is the largest artery and it carries blood to the body as it leaves the left ventricle. Arteries always lead away from the heart. Label the following parts on the diagram provided. As your instructor describes blood flow through the heart, place arrows to show direction of flow. Also, to show where oxygenated and deoxygenated blood would be found, color in red the oxygenated parts and in blue the deoxygenated parts. a. Anterior Vena Cava; Posterior Vena Cava b. Right Atrium c. Tricuspid (right A-V) valve d. Right Ventricle e. Pulmonary semilunar valve f. Pulmonary trunk g. Pulmonary arteries h. Pulmonary veins i. Left Atrium j. Bicuspid (left A-V) valve k. Left Ventricle l. Aortic semilunar valve m. Aorta

On other heart models, also be able to identify: - Sinoatrial node - Chordae tendineae Several major changes occur in circulation at birth, as the lungs begin to function in gas exchange. The fetus relies on the placenta for gas exchange as well as food and waste exchange. The umbilical vein returns oxygenated blood to the fetus where it flows into the posterior vena cava. Therefore, how does blood in the right side of the heart compare before and after birth has occurred?____________________________________________________ Since the lungs are not functional in gas exchange before birth, there are two short circuits to bypass the lungs. These are the ductus arteriosus and the foramen ovale. Describe the position of each of these:______________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________