Sheep Heart Dissection Laboratory Report

Abstract

In this laboratory experiment conducted on July 2002, a sheep's heart was dissected to gain a better understanding of its anatomy and functioning. The heart, a vital muscular organ responsible for pumping blood and nutrients throughout the body, shares similarities with the human heart, making it a suitable model for study. The heart's four chambers, including the left and right atriums (receiving chambers) and the left and right ventricles (pumping chambers), work in a coordinated sequence of contractions to ensure the continuous flow of blood.

This lab aimed to dissect and examine a mammalian heart, develop dissection skills, and investigate the functioning of the heart.

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The procedure involved wearing rubber gloves, placing the sheep heart on a dissection tray, conducting an exterior examination to identify major valves, and making two incisions to explore the heart's internal structures. The results of the dissection provided insights into the heart's anatomy, including the differences in ventricle wall thickness, the presence of chordae tendinae, and the importance of lubrication in specific areas of the heart.

Introduction

The heart is a vital organ in all mammalian bodies, responsible for pumping blood and essential nutrients throughout the circulatory system. A sheep's heart was chosen for this dissection because, like the human heart, it possesses four chambers: two atriums (left and right) and two ventricles (left and right). The coordinated contractions of these chambers play a crucial role in maintaining the cycle of blood through the body, ensuring an uninterrupted flow of oxygen and nutrients.

The heart's functioning involves two primary phases: systolic and diastolic.

The systolic phase occurs when the atriums contract, while the diastolic phase occurs when the ventricles contract. These phases work in a sequential manner to create the heartbeat, allowing blood to circulate efficiently.

The journey of blood through the heart begins with the right atrium receiving blood from the superior or inferior vena cava. As the right atrium fills with blood, the pressure forces the tricuspid valve to open, allowing blood to flow into the right ventricle. From the right ventricle, blood is pumped into the pulmonary arteries, leading to the lungs for oxygenation. The oxygenated blood then returns to the left atrium, passes through the bicuspid valve into the left ventricle, and is propelled into the aorta to supply the body with oxygenated blood.

Aims

The aims and objectives of this dissection procedure were as follows:

1. Dissect and examine a mammalian heart.
2. Develop dissection skills.
3. Conduct an in-depth investigation into the functioning of the heart.

Materials

The materials used in this dissection included:

1. Sheep's heart
2. Scalpel
3. Rubber gloves
4. Dissection tray
5. Paper

Procedure

The dissection procedure was conducted as follows:

1. Begin by wearing rubber gloves to handle the raw heart.
2. Place the sheep heart on the dissection tray.
3. Conduct an exterior examination to identify major valves.
4. Locate a fatty area on the heart to guide the first incision.
5. Make the first incision parallel to the right ventricle, ensuring it is deep enough to gain a proper view.
6. Make the second incision opposite to the first to examine the other side of the heart and view the chordae tendinae.
7. Dispose of the heart properly, along with the gloves, and wash hands after completing the dissection.

Results

During the dissection of the sheep heart, several important features of the heart muscle were observed:

1. The left ventricle wall was thicker than the right ventricle wall. This difference in thickness is because the left ventricle needs additional muscle strength to propel oxygenated blood into the aorta and distribute it to the rest of the body.
2. Stringy structures were found attached to a flap-like structure. These structures were identified as chordae tendinae, which are connected to the bicuspid valve and papillary muscles. Chordae tendinae exhibit remarkable strength because they operate in a high-pressure environment and are responsible for holding the heart's components together.
3. The heart wall in the region where the chordae tendinae are located appeared wetter and slipperier than the rest of the heart. This characteristic is attributed to the need for extra lubrication in this area due to the high mechanical stress it experiences.

Through the dissection, a clearer understanding of the flow of blood through the heart was achieved:

The direction of blood flow in the heart starts with blood entering either the superior or inferior vena cava and then moving into the right atrium. From the right atrium, blood passes through the tricuspid valve into the right ventricle. The right ventricle pumps the blood into the pulmonary arteries, leading to the lungs for oxygenation. After oxygenation, the oxygenated blood returns to the left atrium and passes through the bicuspid valve into the left ventricle. The left ventricle then propels the oxygenated blood into the aorta, which distributes it throughout the body.

Discussion

The dissection of the sheep heart provided valuable insights into its anatomy and functioning. Several key observations were made during the dissection:

1. The difference in wall thickness between the left and right ventricles was noted. The left ventricle exhibited a thicker wall, reflecting its role in pumping oxygenated blood into the aorta to supply the entire body.
2. The presence of chordae tendinae, stringy structures attached to a flap-like structure, was identified. Chordae tendinae are essential for anchoring the bicuspid valve and papillary muscles, ensuring proper valve function and preventing backflow of blood.
3. Notably, the heart wall in the region of the chordae tendinae appeared wetter and slipperier than the rest of the heart. This suggests that this area requires additional lubrication due to the high mechanical stress it experiences during heart contractions.

The dissection also enhanced the understanding of the blood flow through the heart. The heart serves as a pump that continuously circulates blood throughout the body, ensuring the delivery of oxygen and nutrients to all tissues and organs. The coordinated contraction of the atriums and ventricles in the systolic and diastolic phases creates the rhythmic heartbeat responsible for maintaining this circulation.

Conclusion

In conclusion, the dissection of the sheep heart allowed for a comprehensive examination of its anatomy and functioning. Notable findings included differences in ventricle wall thickness, the presence of chordae tendinae, and the need for additional lubrication in specific areas of the heart. Understanding the path of blood flow through the heart is essential to appreciate its role in maintaining circulation and providing oxygen and nutrients to the body's tissues and organs. This laboratory experience provided valuable insights into the complexity and significance of the heart's structure and function.

Recommendations

Further studies in cardiovascular anatomy and physiology can deepen one's understanding of the heart's intricate mechanisms. Exploring advanced techniques and technologies for heart dissection and analysis can contribute to ongoing research in the field of cardiology.