Recently, Mr. Bradley’s Anatomy and Physiology class have been studying the cardiovascular system.Wednesday, March 13, the class was given the opportunity to study the heart first hand. The students were split into groups of two or three, each given their own pig heart to dissect. The pig heart was used because of its close similarities to the human heart in structure, size, and function. The main objective behind the dissection was to educate each student on the circulation of blood through the heart to the lungs and back out to the rest of the body while identifying each major chamber, valve, and vessel in the process.
Starting externally, the first structure of the heart to identify was the pericardium, or thin membrane covering the heart. Once the pericardium was carefully removed, the myocardium, or muscle of the heart, was easily visible. Next, the heart was placed in the dissecting pan in the position it would be in a body as you face it. From here, the four chambers of the heart were located. When looking at the heart, the left atria would actually be the upper right chamber, the left ventricle on the lower right, the right atria on the upper left, and the right ventricle on the lower left. Externally, the major arteries and veins were located the easiest by sticking a finger inside of each and feeling where they branch to. For example, if an opening lead to the upper chamber on the right, you could conclude that the opening was actually the pulmonary vein.
Finally, the fun part began. Scissors were used to cut through the side of the pulmonary artery and continued down into the wall of the right ventricle. The heart was then pushed open at the cut to examine the internal structure. The four chambers of the heart as well as their valves were able to be explored even deeper with this “inside look”. First located inside the heart were the inferior and superior vena cava which enters into to right atrium, or left upper chamber. The tricuspid valve, between the right atrium and right ventricle, was located next by its three leaflets and long fibers of connective tissue called chordae tendinae attaching to papillary muscles. Continuing through the heart, the students located in order of blood flow the pulmonary valve, left atrium, semilunar valves , mitral valve, and left ventricle.
Although the book does a fine job of outlining and displaying the heart, learning hands on through a dissection aids the visual part of the learning process. Being able to study a real heart in the classroom was the perfect way to further each students understanding of the cardiovascular system.