On the of July 2002, a sheep’s heart was examined by dissection. The heart is a muscle in all mammalian bodies that is used to pump blood and nutrients throughout the body.
A sheep’s heart was used in this prac because like the human heart it has four chambers and is similar in size. Two of these chambers are receiving chambers called the left and right atrium. The other two are pumping chambers called the right and left ventricle.
The reliability of the cycle of blood through the body depends on the sequence of contractions from the atrium and the ventricle. When ever the atriums contract it is called the systolic phase. And when ever the ventricles contract, it is called the diastolic phase. These sequences ensure the blood flow through the heart. These occur one after the other to create a heart beat.
The blood flow through the heart starts when the right atrium takes the blood that flows through the superior or inferior vena cava. The right atrium then fills with blood and the pressure of the blood causes the tricuspid valve to open. The blood then travels through into the right ventricle where it pusses the blood into the pulmonary arteries. After this the blood is pumped into the lungs where it is oxygenated, the oxygenated blood travels through the left ventricle then pushes the blood through the aorta, which provides the body with blood.
The aims and goals of this procedure was to:
1.Dissect and examine a mammalian heart
2.Develop dissection skills
3.An in-depth investigation into how the heart works.
Materials used in this dissection were:
The first step in the dissection is to put on the rubber gloves before handling the raw hearts. Next was to place the sheep heart on the dissection tray. After that an exterior examination happened to detect the mail valves. Next was to locate a fatty area on the heart to help guide the first incision into the heart.
Two incisions were required during the procedure. The first one was to be parallel to the right ventricle. The incision must be deep enough to cut into the ventricle to be able to get a proper view.
The second was opposite the first to examine the other side of the heart, to be able to view the chordae tendinae.
After the dissection is completed, the heart must be properly disposed along with the gloves and hands must be washed.
diagram of heart valve system
During the dissection of the sheep heart, features of the muscle were detected. One of these was that the left ventricle wall was thicker then the right ventricles. This is because it uses this extra muscle to propel the blood through the aorta to the rest of the body.
Also some stringy substances holding a kind of flap was found, this was soon made clear that it was the chordae tendinae. It is attached to the bicuspid valve and capillary muscle and had a remarkable strength because it had to work hard in a high-pressure area and hold the heart tougher.
Also in this region, the heart wall was wetter and slipperier then the rest of the heart. This was for extra lubrication.
The flow of blood was made clearer when the heart was opened up.
Diagram of path of blood flow through the heart.
The direction of blood flow through the heart starts from superior or inferior vena cava to the right atrium. Then it passes through the tricuspid valve into the right ventricle to the pulmonary arteries. The blood then goes to the lungs where it is oxygenated comes back down to the pulmonary veins to the left atrium, then passes through the bicuspid valve into the left ventricle where it is propelled through the aorta into the body.