There are three layers of the heart: the epicardium, myocardium and the endocardium. The heart, like a dual pump, which is to pump blood around the whole body, pick-up nutrients and oxygen, at the same time, helping eliminate deleterious wastes, such as carbon dioxide. Moreover, the heart consists of four chambers: two ventricles and two atria. The upper chambers are called atria while the lower chambers are called ventricles, they are separated by valves. Valves are one-way, see Figure 1(Lane, 2010b), hence, they play an important role in preventing the blood from flowing back.
Figure 1 One Way Valve (Lane, 2010b)
The left are right chambers are separated by muscular wall septum. Without this septum, blood from one chamber will be mixed up with the blood from another and be contaminated (Burnell, 2010).
The ventricles have thicker muscles than the atria, they are strong enough to pump the blood out of the heart and circulate to other parts of the body. Besides, the pressure applied on the left ventricle is greater. As a result, the walls of the left ventricle are the thickest among all the walls of chambers (Burnell, 2010).
The coronary artery supply blood to heart muscles and oxygenated, it under the groove on the front the heart and it branches over the front (Lane, 2010b)
The pulmonary artery can carry blood to lungs to incept oxygen. It is used to travel the short distance to lungs because large volume of blood can be passed through and oxygenated. The pulmonary artery locates d of curving out of the right ventricle (Lane, 2010b).
The material and apparatus used in the experiment: the fresh pig heart, dissecting pan, forceps, scalpels, scissors and gloves.
Methods and Observations
Procedure 1: External Structure (Lane, 2010a)
The heart was washed and placed into a dissecting pan.
The colour of heart is pink, white colour exist in the top (maybe this colour is from fatty) and with much dried blood. It can be held by two hands and approximately is 13 cm – 10 cm – 7 cm. The heart is about 0.25 kg.
The pericardium was found a covering the membrane of heart. The pericardium was cut by a scalpel so that the pericardium could be observed. The myocardium was located below the pericardium.
The pericardium is a strong membrane. Thus, it is difficult to remove this membrane. It is about 1mm and colourless.
The apex was located and was pointing down.
The apex is easy to find, it is pink and pointed.
The front of the heart was recognized by a groove that extends from the right side of the broad end to the left of the apex.
There are many veined patterns in the front of heart, judged it in this way: the major blood vessels were on the top half running down to the apex.
There were four chambers in heart. The left and right atria were found.
Left and right chambers are distinct and atria are upper than the ventricles. Also, the left chambers are bigger than right chamber.
Blood vessels at the broad end of the heart were located. The coronary artery was found its position; the pulmonary artery was located by finger curving out of the right ventricle; and the aorta was located behind the pulmonary artery. The pulmonary veins were found at the top of the left atrium. The superior vena cava was found in top of right atrium.
The coronary artery is under the groove on the front of the heart. The pulmonary artery on the right side, the aorta is behind the pulmonary artery both from the top. The diameters of holes are about 3cm. The pulmonary vein is in the left side and behind the superior vena cave. However, the inferior vena cava can not be found.
Figure 2 and Figure 3 are shown the external structure (Xia, 2010).
Procedure 2: Internal Anatomy (Lane, 2010a)
Using scissors, the pulmonary artery was cut through. The wall of the right ventricle was cut down continually, parallel to the groove of coronary artery.
It is easy to cut through and the wall of the right ventricle. The wall is about 1cm thin and very smooth.
A finger was used to push open the heart, the dried blood inside the chambers was washed out.
Many blood clots exist inside. The blood clots are dark and jellified.
The muscular wall of right atrium was measured. The right ventricle was felt the thickness and its smooth textured lining.
The muscular wall of the right atrium was measured, about 1cm. The wall is very smooth.
Inferior vena cava was found in the internal right ventricle, and the lack of valves was noticed.
Inferior vena cava in the inside chamber lower left, which locate in right ventricle, near apex.
The valve between the right atrium and right ventricle was observed.
The valve between the right atrium and right ventricle is thin and easy to break. It was not easily seen.
The network of irregular muscular cords was noticed.
The network of irregular muscular cords was found everywhere. The colour of them is pink and ropy. It is hard to destroy.
The septum on the right side of the right ventricle was found.
The septum on the right side of right ventricle is very thick about 1.5cm.
Using a finger, the pulmonary artery was followed to locate the right ventricle. The pulmonary valve was found.
The pulmonary valve is very thin about 1mm and not seen to be intact.
Figure 3 is shown the right side of heart (Xia, 2010).
Using scissors, the heart was cut on the outside of left atrium downward into the left ventricle cutting toward the apex to septum at the center groove. The heart was cleaned.
The wall of the left atrium is about 2.5cm. The wall of the left ventricle is thicker, about 3 cm and hard to cut through. Jellified bloods were washed.
Semi-lunar valves were found.
Semi-lunar valves are consisting two valves, about 1mm and pink.
Mitral valve was found.
The two parts of valves were seen and about 1mm.
The left ventricle was cut across toward the aorta, to expose any valves.
The left ventricle is hard to cut because the wall is about 3cm.
The aortic valve was found.
The valve is consisted of three flaps, the shape as half-moon, about 1mm.
Figure 5 is shown the left side of heart (Xia, 2010).
Figure 6 is shown the internal anatomy (Xia, 2010)
Figure 2 The Front View of Heart (Xia, 2010)
Figure 3 The Rear View of Heart (Xia, 2010)
Figure 4 The Right Side of Heart (Xia, 2010)
Figure 5 The Left Side of Heart (Xia, 2010)
Figure 6 The Internal Structure (Xia, 2010)
All these figures are at the end of report in the appendix.
Initially, because the structure of heart is unfamiliar, the process was done slowly, and many aspects are uncertain. In addition, before the experiment a picture of heart structure was found, during the experiment the picture was used to compare with the real heart so that identification can be more easily achieved to find structures position. However, the correct position of picture is different from position in the real heart. The reasons may the diagram is idealized, the real heart is empty and collapsed, structures lack colour contrast to distinguish.
When the wall of left ventricle was cut, it is more difficult to sever than the right ventricle. During procedure 2, some muscular cords were cut and some places were undistinguishable. The wall of left ventricle is much thicker than right wall because the left ventricle did the major work.
The handout suggested that watching the diastole and systole of the heart. However, this is a departed pig heart, thus, the phenomenon can not be seen. In addition, valves are very thin, when the heart is cut, valves are easily destroyed by mistake, such as the pulmonary valve is not seen to be intact.
During the experiment, the heart was examined, its external structure, each vessel’s characteristic and position was found and recognized. In the internal anatomy, different positions of valves were found. Dimensions of different parts of heart were measured: the size of heart, the pericardium, the diameter of vessel’s holes, the wall of the right ventricle and atrium, the wall of the left ventricle and atrium, the thickness of semi-lunar valves, the thickness of mitral valve, the thickness of aortic valve.