Introduction

Like in human beings, the sheep ha a four chambered heart. Medical practitioners and other biomedical students dissect the sheep heart with an aim of learning how the human hearts anatomy is and how this heart functions. One is able to understand the aspects of the heart in terms of the valves delicacy, great vessels thickness and how the walls of the two ventricles differ in thickness.

The human heart size is close to that of a sheep heart though there are a few differences. The human heart is larger than fist and weighs less than a pound and it is approximately two times that of the sheep. It pumps blood to all body parts. The upper chamber of the heart is the atrium and the lower chamber is the ventricles.

Dissecting of sheep heart is less messy because there is little fluid in the heart thus making the dissection clean and dry. When the students dissect and observe the sheep heart, they learn on how the heart looks like and how it really works. Students undertake the exercise with an aim of understanding the basic circulatory system by fist having to identify the different four chambers of the heart, the heart valves, and vessels of blood flowing in and out of the heart. This way, the students are able to compare the heart they are dissecting with the one they read in the text books.

Material and method

Students should be in laboratory coats and in protective gloves to prevent contact with unnecessary fluids and more so potential germs. They should also be in goggles. After the students identified the right and the left side of the heart, they found the diagonal line made by blood vessels that divide the heart. The right half is looser than the left half. The right side was examined and auricles were identified as ear-like flaps. The large opening at the top of the right auricle was also found. A probe was inserted at the left of the superior vena cava where another blood vessel opening is found.

Next to the left auricle is pulmonary vein. The aorta is seen sticking from the centre of the heart. Pulmonary artery is then seen behind the aorta to the left.

So as to view the internal anatomy of the heart, a scalpel was inserted at the superior venacava and an incision made down. The two sides were separated and three flaps of membrane were seen.

These membranes make the tricuspid valve. An incision is made through the pulmonary artery where three small membranous pockets are seen. These pockets form the pulmonary semilunar valve. Make another incision at the left auricle at the base of aorta and look for mitral valve found between the atrium and the ventricle. This valve has two flaps of membrane. Finally make an incision through the aorta up and look for some other three membranous pockets which form the aortic semilunar valve

Results

It was found out that sheep heart resembles the human heart and has four chambers.

The left side of the heart is firmer than the right side because it is the side that pumps blood to the entire body.

The large opening next to the right auricle at the top of the heart is called the vena cava and it brings blood to the right atrium.

Inferior venacava brings blood to the lower tissue while the pulmonary vein brings blood to the left atrium from the lungs. Aorta gets oxygenated blood from the left ventricle to all the body parts. The pulmonary artery gets blood from right ventricle to the lungs. Tricuspid valve allows blood to pass to the ventricle from the atrium, and prevents backflow of blood from the ventricle to the atrium. Pulmonary semilunar valve prevents blood from going back to the right ventricle. Aortic semilunar valve prevents flow of blood back into the left ventricle.

Discussion

From the results it is true that really the sheep heart resembles that of human being a lot and that the students can dissect it as an aid in the understanding how different heart structures look like and how they perform their functions. Just like the human heart, the sheep heart has four chambers which are the right and the left atrium on the upper half and the right and the left ventricles on the lower half. Different arteries were seen as there are in the human heart and also the valves that control the flow of blood just as in the case of human being. Dissection of the sheep heart is there fore necessary for biology students who wish to have a better understanding of the human heart in terms of its anatomy and functions.

References

Frink R. J. and B. Merrick, The sheep heart: Coronary and conduction system anatomy with special reference to the presence of an os cordis, 2005.

Guyton, A. C. and Hall, J. E., Textbook of Medical Physiology, 11th ed, Philadelphia, Elsevier Saunder, 2006.

Marieb, E., Human Anatomy & Physiology. 6th ed. Upper Saddle River, Pearson Education, 2003.

R Sherwood and S. Thomas, The Vertebrate Body, Holt-Saunders International, Philadelphia, PA, 1977, pp.

Marieb, E., Human Anatomy & Physiology. 6th ed. Upper Saddle River, Pearson Education, 2003.

Guyton, A. C. and Hall, J. E., Textbook of Medical Physiology, 11th ed, Philadelphia, Elsevier Saunder, 2006.

Frink R. J. and B. Merrick, The sheep heart: Coronary and conduction system anatomy with special reference to the presence of an os cordis, 2005.

Sherwood and S. Thomas, The Vertebrate Body, Holt-Saunders International, Philadelphia, PA, 1977, pp.