The Circulatory System

BY Olivia Collings

The left side of the heart. The bicuspid valves are easily visable.

Sheep's Heart Dissection

1. Describe the appearance of the heart. What does it look like? How does it feel? Are there any features you can describe? The exterior is a red/pink colour with hard, thick, white/yellow fat around the rim of the heart. The muscle is very thick.

3. Find the blood vessels on the surface of the heart muscle. These are the coronary arteries. They carry nutrients and oxygen to the heart muscle.Describe what this artery looks like.Thin; 3mm thick, a bright red. It branches off into lots smaller muscles.

What do you think would happen if this artery was blocked by a clot? If the coronary artery was blocked by a clot, the heart would be unable to receive oxygen and nutrients required to function thus resulting in a heart attack.

4. How do you know which side is the left and right side of the heart? The right side of the heart is smaller as it only needs to pump blood to the lungs, the left is bigger because it pumps blood all around the body.

5. Have a feel of the thickness of the heart muscle at the top and the bottom of the heart. Describe the following features: a. The thickness of the muscles at the top of the heart Less than one centimeter. It is thin because it doesn't do any pumping. It only recieves returning blood. b. the thickness of the muscles at the bottom of the heart The thickness of the bottom heart was much thicker than the top of the heart because the ventricle pumps blood out. c. The amount of fat surrounding the heart The fat was concentrated around the top of the heart and almost none at the bottom. d. Any major vessels entering and exiting the heart Pulmonary vein and the inferior vena cava. These are much thinner than the arteries, because the blood is going back to the heart, they don't need to be thick because the blood is only trickling back.

6. Choose the correct answer Oxygenated/Deoxygenated blood leaves the right ventricle/right atrium in an artery/vein and travels to the lungs/rest of the body. Here the blood collects oxygen/drops off oxygen, so it is now oxygenated/deoxygenated. The blood travels back to the heart via an artery/vein.

7. Find the aorta that carries the blood away from the left ventricle of the hearta. describe the thickness of the vessel. Why do you think it needs to be so thick? 2cm thick. It is the main artery so it needs to be thick. It pumps blood all around the body so it need to be strong and withstand the high pressure. b. Where is it taking blood to? All around the body

8. Find the vena cava. This is the vein that returns blood from the bodya. compare the thickness of the vena cava to the aorta. Why do you think it is different?The vena cava doesn't have any thick, muscular tissue because it is very low pressure. To return to the heart the blood is only trickling back. b. What part of the heart does the vena cava go back into? The right atrium c. Remember what you observed when you observed the water flowing through the heart. The water went into the vena cava and into the heart. Which blood vessel did the water come out of the heart from? The pulmonary atery.

9. When the water was flowing in the pulmonary vein, which vessel did it come out of? Aorta


1. Describe what you see inside the left side of the heart:Thick pink/red muscle tissue, white stringy valves.

2. Observe any valves you see. What do you think their job would be? To stop blood travelling the wrong way (reflux)

3. Cut the aorta. Describe how it appears and how it feels Tough and thick. With strong elastic walls.

4. Cut the atria of both the left and right sides so you can see the muscle thickness of all four chambers. Fill out the table below:

5. In the table below, indicate the location and role of the following structures:

6. In the diagram below, label the parts of the heart. Indicate the direction of blood flow around the body, use blue and red pencils to indicate oxygenated and deoxygenated blood. Indicate where the blood has come from and where the blood is going.

label the parts of the heart

Conclusion - How the circulatory system links with the respiratory system

When the heart pumps blood from the right ventricle into the pulmonary artery to the lungs to collect oxygen. The pulmonary vein branches out into a network of capillaries that bypass the alveoli in the lungs and the red blood cells pickup oxygen and drop off carbon dioxide.

The box diagram