The document summarizes a student lab where a group dissected a fetal pig to observe the circulatory system. They hypothesized that the circulatory system could be observed since fetal pigs are mammals similar to humans. During the dissection, the students identified structures like the heart chambers, veins and arteries. They observed that arteries carry oxygenated blood away from the heart while veins bring deoxygenated blood back to it. The dissection supported the hypothesis that the human circulatory system could be accurately observed in a fetal pig.

2. Start date: 4/5/12
End date: 4/6/12
Project members: Naheen, Kyle, Mesha, Amna, Sandhya
Teacher’s name: Mr. Green
Background Information:
All organisms must exchange materials within their environment, including nutrients and wastes, such
as oxygen and carbon dioxide. Also known as the cardiovascular system, the circulatory system is
composed of the heart, arteries, and veins. There are four chambers in the heart, two atria and two
ventricles (right and left). The right atrium receives deoxygenated blood from the body (high in carbon
dioxide) and sends it to the right ventricle, which pumps the blood through the pulmonary arteries.
These arteries lead to the lungs, which oxygenate the blood and sends it to the left atrium. After
flowing into the left ventricle, the aorta pumps the oxygenated blood to all body cells. This system is
essential for moving nutrients and wastes to and from cells and therefore, maintaining homeostasis.
In this investigation, we will discover how the circulatory system can be observed in fetal pigs.

3. Purpose: How can we observe the circulatory system of the human body in fetal pigs?
Hypothesis: If we believe that fetal pigs are mammals with similar body forms and organs as humans, then we should
be able to observe the organs of the circulatory system in the body of the fetal pig and how it functions.
Materials:
•Fetal pig
•Dissecting tools (scalpel, scissors, probe)
•Disposable gloves
•Camera
Procedure:
1.) Place the fetal pig on its back in the dissecting pan.
2.) Tie a cord around one forelimb, and then bring the cord around underneath the pan to fasten back the other
forelimb.
3.) Spread the hind limbs the same way.
4.) With the scissors always pointing up, make incisions to expose the thoracic and abdominal cavities.
5.) Cut up from the diaphragm until you reach the hairs in the throat region.
6.) Make two lateral cuts, one on each side of the midline incision anterior to the forelimbs.

4. 7.) Make two lateral cuts, one on each side of the midline just posterior to the forelimbs and anterior to the
diaphragm, following the ends of the ribs. Pull back the flaps created by these cuts to expose the thoracic cavity.
8.) Once the blood vessels of the circulatory system (in the thoracic cavity) have been identified, remove the heart
from the cavity and cut it open.
9.) Identify the chambers and valves of the heart.
Observations:
Fetal pig
Thoracic cavity and other organs exposed

5. Back of heart

6. Dissection
of the
heart
Front of heart

7. Blood Vessels Type of Blood Organ or Structure
Observed Carried Serviced by Blood
Vessel
Superior/Inferior Vena Deoxygenated Heart (right atrium)
Cava
Pulmonary arteries Deoxygenated Right ventricle to lungs
Aortic trunk Oxygenated Left ventricle to body
Carotid arteries Oxygenated Heart to head and neck
Jugular veins Deoxygenated Head to heart
Renal arteries/veins Oxygenated Blood to kidneys

8. Analysis:
In this lab, I was able to observe the human circulatory system in a fetal pig. The purpose of the circulatory system is to
transport blood to deliver important substances, such as oxygen, to body cells and remove wastes, such as carbon
dioxide. The heart pumps blood through a vast network of tubes, known as the blood vessels. Blood also carries
disease fighting materials for the immune system and distributes heat to regulate body temperature. Arteries carry
oxygenated blood away from the heart. They are strong, thick walled vessels that are elastic and durable. Arteries
need to be capable of high pressure because of the force of the blood being pumped away from the heart. Their outer
layer consists of connective tissue, with smooth muscle in the middle layer and endothelial tissue in the inner layer.
Veins bring deoxygenated blood to the heart and have thinner walls, since they are driven by blood circulation. The
pulmonary arteries carry blood that is high in carbon dioxide away from the right ventricle and into the lungs. The
aorta is the largest blood vessel in the body and the left ventricle uses it to send blood to body cells. The pacemaker,
also known as the sinatrial, is located in the right atrium and receives information about the body’s oxygen levels. If
detected low, it will adjust the heartbeat rate (faster).
The chamber with the thickest walls is the left ventricle, because it has to propel blood into the systemic circuit. The
right ventricle only sends deoxygenated blood to the lungs and the atria only have the empty the ventricles. When
dissecting the pig and observing the heart, it can be noticed that the pulmonary veins were colored red. This is
because the pigs were injected with dye. Since the pulmonary veins carry deoxygenated blood, it would make sense
for this blood to be blue. In order to differentiate between arteries and veins without being able to see the colors of
the blood, it is essential to notice that veins are thinner and send blood to the heart. Arteries are much thicker and
send blood away from the heart.

9. Conclusion:
In conclusion, my hypothesis was correct. We can accurately observe the human circulatory system in a
fetal pig. During this investigation, I was able to observe several organs and their properties, whose
functions take place actively in our bodies.
Fetal pigs are often used in classroom dissections. These mammals have similar hair, organ systems,
metabolic levels, and body forms as humans. Their soft tissue and underdeveloped bones (cartilage)
make them easier to dissect than other organisms. The circulatory system of a fetal pig is different from
that of an adult pig because there is a shunt between the wall of the right and left atrium, which would
allow blood to pass directly from the right atrium to the left. This closes shortly after birth.
I was able to learn countless things during this lab. When dissecting a fetal pig, it is important to have
patience when handling the equipment and making incisions on organs. Accidental incisions can result
in damaging organs of the specimen.