Comparative Anatomy Dissection 6: The Pig Heart
Learning Objectives:
1. Students will observe the major chambers, valves, and vessels of the heart.
2. Students will describe the circulation of blood through the heart to the lungs
and back and out to the rest of the body.
The pig heart is used because it is very similar to the human heart in structure, size and function.
Part 1: Examining the Exterior of the Pig Heart
1. Place a heart in a dissecting pan with the ventral side up. The major blood vessels are on the top and
the apex is down). The front of the heart is recognized by a groove that extends from the right side of
the broad end of the heart diagonally to a point above and to your left of the apex.
2. Examine the heart and locate the thin membrane or pericardium that still covers the heart. The
pericardium is a double-layered closed sac that surrounds the heart and anchors it.
3. The heart is in the pan in the position it would be in a body as you face it. Locate the following
areas of the heart and then LABEL them on the heart diagram.
 Left Atrium
 Left Ventricle
 Right Atrium
 Right Ventricle
 Apex
 Septum
 Check In: Prediction: Why are there smaller blood vessels along the front side of the heart that
don’t lead directly to the lungs?
4. While the heart is still in this position in the dissecting pan, locate these blood vessels at the
broad end of the heart and LABEL them on your heart diagram.
 Pulmonary artery - this blood vessel branches and carries blood to the lungs to receive
oxygen and can be found curving out of the right ventricle (upper chamber to your left)
 Aorta - major vessel located near the right atria and just behind the pulmonary arteries to
the lungs. The curved part of this vessel is known as the aortic arch. Branching from the
aortic arch is a large artery that supplies oxygenated blood to the upper body.
 Pulmonary veins - these vessels return oxygenated blood from the right and left lungs to
the left atrium (upper chamber on your right)
 Inferior and Superior Vena Cava - these two blood vessels are located on your left of the
heart and connect to the right atrium (upper chamber on your left). Deoxygenated blood
(has very little or no oxygen) enters the body through these vessels into the right atrium.
 Check In: Which of the blood vessels is the most muscular? Why do you think this is true?
Part 2 Examining the Interior of the Pig Heart
5. Use scissors to cut through the side of the pulmonary artery and continue cutting down into the
wall of the right ventricle. Be careful to just cut deep enough to go through the wall of the heart
chamber. (Your cutting line should be above & parallel to the groove of the coronary artery.)
6. With your fingers, push open the heart at the cut to examine the internal structure. Locate the
right atrium and find where the inferior and superior vena cava enter this chamber.
7. Locate the valve that between the right atrium and right ventricle. This is called the tricuspid
valve. The valve consists of three leaflets & has long fibers of connective tissue called chordae
tendinae that attach it to muscles of the heart. This valve allows blood flow from the right
atrium into the right ventricle
but snaps shut when the heart
beats to prevent blood from
going back up into the atrium.
8. Use your fingers to feel the
thickness of the right ventricle
and its smooth lining.
 Check In: Which chamber has
thicker walls, the right atrium
or the right ventricle? Why do
you think this is so?
 Check in: Describe the muscle
fibers on the inner wall of the
ventricle. Are they parallel
lines or intersecting lines?
9. Find the septum on the right side
of the right ventricle. This thick
muscular wall separates the right
and left pumping ventricles from
each other.
10. Inside the right ventricle, locate
the pulmonary artery that
carries blood away from this
chamber. Find the one-way valve
called the pulmonary valve that
controls blood flow away from
the right ventricle at the entrance
to this blood vessel.
11. Using your scissors, continue to cut open the heart. Start a cut on the outside of the left atrium
downward into the left ventricle cutting towards the apex to the septum at the center groove. Push
open the heart at this cut with your fingers.
12. Examine the left atrium. Find the openings of the pulmonary veins form the lungs.
13. Inside this chamber, look for the valve that controls blood flow between the upper left atrium and
lower left ventricle. This valve is called the bicuspid or mitral valve. This valve consists of two
leaflets and keeps blood from flowing backwards from the left ventricle into the left atrium.
10. Using your scissors, cut across the left ventricle toward the aorta & continue cutting to expose the
valve.
11. Count the three flaps or leaflets on this valve leading from the left ventricle into the aorta and note
their half-moon shape. This is called the aortic valve.
12. Using scissors, cut through the aorta and examine the inside. Find the hole or coronary sinus in the
wall of this major artery. This leads into the coronary artery which carries blood to and nourishes the
heart muscle itself.
 Check In: Label the following structures on the heart diagram.
 Tricuspid Valve
 Pulmonary Valve
 Mitral Valve
 Aortic Valve
 Clean Up: Wipe off all tools with the wet wipes and put them away in the kit correctly. Wipe
out your pans with a paper towel and put the hearts back in their individual bags. Put both
bags in your pan.
Analysis Questions: Complete the following questions in the space provided on this sheet. This
completed lab report is due on Monday 6 June, 2011. If you need extra assistance, use the resources
available on the Comparative Anatomy page of the class wikispace. Do it!
1. What is the main function of the circulatory system?
2. How are the functions of arteries and veins similar and different?
3. How is blood found in the vena cava different from the blood found in the aorta?
4. Explain how the flow of blood in the circulatory system is similar to a “Figure 8”.
5. Write a paragraph describing your three main take-aways from the pig heart dissection and
any additional observations you now have about the heart.
CHALLENGE QUESTION: Put the following terms in order as blood flows through them starting
with the vena cava and ending with the aorta.
Aorta, left atrium, left ventricle, mitral valve, pulmonary artery, pulmonary veins, right
atrium, right ventricle, tricuspid valve, vena cava.