This assignment will describe my personal experience whilst participating in a heart dissection. It will explain the internal and external heart structure and detail the structure of blood vessels in relation to their function. This assignment will also describe what I did, saw and felt during my participation.
My first thought when the sheep’s heart was given to our group was how fatty it looked to be. At first glance, the heart seemed to be covered in a thick and creamy white Adipose tissue. We later learned that a sheep’s heart has much more fat than a human heart and that a human heart would be much leaner and a little larger.
When holding the heart, I first realised how tough the muscle felt and could easily notice that the left ventricle wall was much thicker than the right ventricle wall. This is due to the vast amount of contracting the left ventricle wall has to undertake in comparison to the smaller amount required by the right ventricle wall.
We could then see clearly that from the right ventricle, the blood would have been pumped into the pulmonary artery. This is the only artery that carries deoxygenated blood. The pulmonary artery was quite thin and rubbery and would then have split into two tubes, the left and right arteries. These arteries then carry blood to the lungs. We could not see the split in the arteries during the dissection but we did find the pulmonary valve which comprised of three semi lunar cusps. This valve prevents the backflow of blood into the right ventricle. We then discovered the two pulmonary veins, these veins carry oxygenated blood back to the left atrium. They were slim, rubbery and flexible. We were then shown the location of the atriums on the heart. I was shocked to learn how small the left and right atriums actually were. They were simply small, brown flaps of tissue. They would enlarge when filled with blood. We then discovered the huge coronary artery. It was very prominent and looked like a large, thick, silvery vein that ran from one
side of the heart to the other.
The interior wall of the heart was smooth and shiny. This is to allow the smooth flow of blood within the heart. We then cut down the right ventricle which exposed the tricuspid valve between the right atrium and ventricle. These valves work to control and direct blood flow. Inside the ventricle was an empty space, this is where the blood gathers once it has passed through the tricuspid valve from the right atrium. The tricuspid valve looked like a flap of thick skin, we tested the strength of the skin with a probe and it was surprisingly tough and stretchy. This strength is needed as the valve closes once the ventricle is full to ensure that there is no backflow of blood into the atrium. The septum also became visible once the ventricle was opened. It was very thick, it was possibly the thickest muscle within the whole heart.
The next step was when we cut through the left ventricle, immediately the difference in thickness between the right and left ventricle was apparent. It was quite tough to cut through the left ventricle wall, we first used scissors and then had to use a scalpel to gain access all the way through. Whereas with the right ventricle wall, scissors sufficiently cut through the wall as it was much thinner. The two ventricles overall had quite thick walls these work by contracting to squeeze blood out into the arteries, although the left ventricle does considerably more work than the right.
From the left atrium, the blood would pass through the bicuspid valve and into the left ventricle. Again, we located the stretchy valve and found that it was very strong under pressure as we tried to stretch it with our fingers. The blood would then have been pumped into the aorta which then pumps blood to the rest of the body. The pulmonary artery and the aorta were very visible during the dissection. The aorta felt quite rubbery and stretchy. I could fit my finger through the creamy white coloured aorta and it lead down through the valves into the left atrium and ventricle. At the opening of the aorta we discovered an aortic valve which is formed by three semi lunar cusps. It was much like the other valves that we had seen, translucent, very rubbery and strong.
Once we had located most of the main components of the heart, we cut a small chunk of Adipose tissue from the exterior at the top of the heart, next to the left atrium. I rolled a lump of the tissue between my fingers and it felt like soft wax, it was very pliable. We then investigated the inside of each ventricle, the walls were shiny, smooth and muscular.
Overall, I feel that the heart dissection was very useful and informative. I now feel more confident in recognising the different components of the heart. I think it was unfortunate that the superior and inferior vena cava were missing during the dissection due to the way the heart had been prepared. I feel it would have been great to see if their image and consistency was as I expected it to be but other than that I feel it was a completely positive and educational experience that I would like to take part in again.