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IGCSE Coordinated Sci. Y2
Mammalian Heart Dissection
Objective
Using a pig, sheep or cow heart, students will observe the major chambers, valves, and vessels
of the heart and be able to describe the circulation of blood through the heart to the lungs and
back and out to the rest of the body. (The pig, sheep, or cow heart is used because it is very
similar to the human heart in structure, size, & function.)
Materials
Dissecting pan,
dissecting kit,
safety glasses,
gloves,
mammalian heart,
lab apron
Procedure - External Structure
1. Place a heart in a dissecting pan & rinse off the excess preservative with tap water. Pat the
heart dry.
2. Locate the tip of the heart or the apex. Inside, only the left ventricle goes all the way to the
apex.
3. Place the heart in the dissecting pan so that the front or ventral side is towards you (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 & to your left of the apex.
a) Sketch an external diagram of the heart
in your science journal. Label the apex.
b) label the approximate location
of each of the major chambers.
- right atrium
- right ventricle
- left atrium
- left ventricle
Figure 1
IGCSE Coordinated Sci. Y2
4. The heart is now in the pan in the position it would be in a body as you face the body. Locate
the following chambers of the heart from this surface:
Left atria - upper chamber to your right
Right atria - upper chamber to your left
Left ventricle - lower chamber to your right Right ventricle - lower chamber to your left
5. While the heart is still in this position in the dissecting pan, locate these blood vessels at the
broad end of the heart:
Coronary artery – (very hard to see) this blood vessel lies in the groove on the front of the heart
& it branches over the front & the backside of the heart to supply fresh blood with oxygen &
nutrients to the heart muscle itself.
Pulmonary artery - this blood vessel branches & carries blood to the lungs to receive oxygen &
can be found curving out of the right ventricle (upper chamber to your left)
Aorta - major vessel located near the right atria & just behind the pulmonary arteries to the
lungs. Your aorta might have a curved part of this vessel known as the aortic arch. Branching
from the aortic arch is a large artery that supplies blood to the upper body.
Pulmonary veins - these vessels return oxygenated blood from the right & left lungs to the left
atrium (upper chamber on your right)
Inferior & 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 enters the
body through these vessels into the right receiving chamber.
a. Examine the dorsal (back) surface of the heart (Figure 2) Locate the stumps of two
relatively thin-walled blood vessels that enter the right atrium. The upper vessel is the
superior vena cava, and the lower one is the inferior vena cava.
b. Use your blunt probe to feel down through the superior vena cava into the right atrium
and then try to pass the probe out the inferior vena cava.
IGCSE Coordinated Sci. Y2
Procedure - Internal Anatomy: Right Side
6. Open the right atrium. To do this, follow these steps:
a. Make a long cut through the right atrium.
b. Lift the edges of the flaps and observe the wide openings where the inferior &
superior vena cava enter this chamber & notice the lack of valves.
c. Notice the thinner muscular wall of this receiving chamber.
7. Locate the valve between the right atrium and ventricle. This is called the right
atrioventricular valve, or tricuspid valve. The valve consists of three leaflets & has long fibers of
connective tissue called chordae tendinae (“tendons”) that attach it to papillary muscles of the
heart. This valve allows blood flow from the right atrium into the right ventricle. It closes when
the ventricle contracts.
8. Open the right ventricle as follows:
a. Continue cutting downward through the atrioventricular valve and the right
ventricular wall until you reach the apex of the heart.
b. Find the opening to the pulmonary artery and use the scissors to cut upward through
the wall of the right ventricle. Follow the pulmonary trunk until you have exposed the
right semi-lunar valve.
c. Examine the valve and its cusps.
9. Use your fingers to feel the thickness of the right ventricle and its smooth lining. Also note
the network of irregular muscular cords on the inner wall of this chamber.
10. Find the septum on the right side of the right ventricle. This thick muscular wall separates
the right & left pumping ventricles from each other.
11. Inside the right ventricle, locate the pulmonary artery that carries blood away from this
chamber. Find the one-way valve called the right semi-lunar valve that controls blood flow
away from the right ventricle at the entrance to this blood vessel.
IGCSE Coordinated Sci. Y2
Internal Anatomy: Left Side
12. Open the left atrium by cutting from the top of the atria down toward the ventricle along
the side ridge of the left ventricle:
a. Determine the number of blood vessel openings draining into the left atrium. These
openings belong to pulmonary veins that drain blood from the lungs. How does the wall of the
left atrium differ from that of the right atrium?
13. Start a cut on the outside of the left atrium downward into the left ventricle cutting toward
the apex until you reach the septum . Push open the heart at this cut with your fingers & rinse
out any dried blood with water. Your heart should now be completely divided in half.
14. Inside the left chambers look for the valve that controls blood flow between the upper left
atrium and lower left ventricle. This valve is called the left atrioventricular valve, or bicuspid
valve.
15. Examine the left ventricle. Notice the thickness of the ventricular wall. This heart chamber
is responsible for pumping blood throughout the body.
16. Using your scissors, cut from the apex through the septum toward the aorta & continue
cutting to expose the valve.
17. 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 left semi-lunar or aortic valve.
18. Using your paper heart model, practice describing the flow of blood through the heart with
a partner in your group.
When you have finished dissecting the heart, dispose of the heart as your teacher advises
(NOT in the trash). Clean, dry, and return all dissecting equipment to the lab cart. Wash your
hands thoroughly with soap.
IGCSE Coordinated Sci. Y2
End of Activity (expected learning)
After you have dissected the heart (resource: https://www.youtube.com/watch?v=yE3Y-XR8Ax4)
then you should be able to answer the following questions below:
1. How can you tell which side of the heart is the ventral surface?
2. How many chambers are found in the mammalian heart? List these chambers.
3. Which chambers are the pumping chambers of the heart?
4. Which chambers are the receiving chambers of the heart?
5. Compare the structure of the tricuspid valve with that of the pulmonary valve.
6. How do the walls of the atria compare with the walls of the ventricles and why are they
different?
8. What is the purpose of heart valves? Name & compare the heart valves found between the
upper & lower chambers of the right and left sides of the heart.
9. Vessels that carry blood away from the heart are called __________, while __________ carry
blood toward the heart.
10. Which artery is the largest and why?
11. What is the purpose of the coronary artery and what results if there is blockage in this
vessel?
12. Can an artery carry deoxygenated blood? Explain.
This heart dissection activity should help you to understand the content from B5.2 Transport in
Humans. This activity with resources, lectures, and demos from your teacher should help you
to cove the following Content Objectives from the syllabus.
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Describe the circulatory system as a system
of tubes with a pump and valves to ensure
one-way flow of blood
Describe the structure of the heart
including the muscular wall and septum,
atria, ventricles, valves and associated
blood vessels
Describe the function of the heart in terms
of muscular contraction and the working of
the valves
Name the main blood vessels to and from
the heart, lungs, liver and kidneys
Describe double circulation in terms of a
low pressure circulation to the lungs and
a high pressure circulation to the body
tissues and relate these differences to the
different functions of the two circuits
IGCSE Coordinated Sci. Y2
Supplementary Web Resources:
Interactive anatomy of sheep heart (Gateway Community College, AZ):
http://www.gwc.maricopa.edu/class/bio202/heart/anthrt.htm
Images of sheep heart dissection (Penn State Univ.):
http://www.bio.psu.edu/faculty/strauss/anatomy/circ/circulat.htm
Images of the human heart (University of Utah Health Sciences Center):
http://www-medlib.med.utah.edu/WebPath/CVHTML/CVIDX.html#1
This lab manual was adapted from: http://www.cohs.com/teachers/docs/155_bisc104-lab_08.pdf &
http://www.nsummit.k12.ut.us/highschool_root/html/Teacherpages/Marsh/BiologyFolders/StandardIII/ObjectiveIII/Pdf/Heart%20Dissection%20Lab.pdf