Dissecting Procedures for a Sheep Heart

Sheep heart dissections are popular in biology classes because the heart represents the anatomy of a human heart and provides accurate information on the functionality and purpose of a heart. Although many dissections can be messy, sheep heart dissections are quite dry and clean since there is little to no fluid in the heart. As with all dissections, protective latex gloves should be worn at all times to avoid contact with leftover liquid and keep your hands free from potential germs.

External Identification

• Before physical dissection can begin, you should first be able to externally identify the parts of the sheep heart. Usually these are labeled during a class dissection, but they can be unlabeled during lab exams. Studying ventricles can be difficult since they are labeled respective to the sheep. When examining left and right ventricles, remember that the left ventricle is respective to the sheep, so your left would be the sheep's right. You can also use the apex to determine each side of the heart. The apex is the cornered lower tip of the heart and is located on the left side of the heart. By squeezing each side of the heart you can feel the muscular difference between the left side, which pumps blood to the entire body, and the right side which pumps blood solely to the lungs.

  Once surface external identification is done, move on to the top section of the heart to identify more parts. Locate two slightly discolored flaps on either side of the top section of the heart. These are the auricles or pouches extending from the left and right atriums of the heart. The atriums are located inside the heart and are seen during the internal dissection. Click the "Reference" link (below) to identify more external part of a sheep heart including the superior vena cava, the pulmonary vein and the aorta, which is responsible for transferring blood to the rest of the body.

Internal Dissection

• The tools you will need to perform an internal dissection include a scalpel, dissecting scissors and a probe. These instruments are part of a dissection kit and can be purchased at college bookstores or purchased online at science shopping outlets. Sharp dissection instruments should only be used under the supervision of a teacher or individual experienced in handling this type of equipment.

  To begin the internal dissection, place your dissecting scissors into the superior vena cava opening and gently cut directly down through the right ventricle. You should be able to open the heart through this incision and view the right atrium and ventricle. Inside the heart are muscles and tissues like the chordae tendinae and papillary muscles that help pump blood and prevent blood from flowing back into the atrium.

  Make an incision on the left side of the heart by cutting through the left auricle and down to the left ventricle. Open the incision and locate important parts such as the mitral valve and the left atrium. Papillary muscle and chordae tendinae tissue can also be seen through this incision. To view the pathway of the aorta, insert your probe into the aortic opening. For more in-depth sheep heart dissection information, informative diagrams and practice sheets visit the link below.