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Heart Dissection Procedures
Procedure - External Structure
1) Place a heart in a dissecting pan & rinse off the excess preservative with tap water. Pat the heart
dry.
ASK THE WRITER TO FIND THE
LOOKING FOR!
ON THE LAB SHEET SO YOU KNOW WHAT YOU ARE
2) Examine the heart and locate the thin membrane or pericardium that still covers the heart. The
pericardium or pericardial sac is a double-layered closed sac that surrounds the heart and
anchors it. After examining the pericardium, carefully remove this tissue.
3) Located below the pericardium is the muscle of your heart called the myocardium. Most of the
myocardium is located in the lower two chambers of the heart called ventricles.
4) Identify the right and left sides of the heart. Look closely and on one side you will see a
diagonal line of blood vessels that divide the heart. The half that includes ALL OF THE
APEX (pointed end) of the heart is the left side (YOUR RIGHT SIDE).
a. Confirm this by squeezing each half of the heart. The left half will feel much firmer and
more muscular than the right side. (The left side of the heart is stronger because it has to
pump blood to the whole body. The right side only pumps blood to the lungs.)
5) Find the flaps of dark tissue on the top of the heart. These ear-like flaps are called auricles.
6) Turn the heart so that you are looking at its DORSAL SIDE. Find the large opening at the top of
the heart next to the right auricle. This is the superior vena cava, which brings blood from the
top half of the body to the right atrium (the atria are the top chambers in the heart). Stick a
BLUE COLORED PENCIL down this vessel. You should feel it open into the right atrium.
7) A little down and to the left of the superior vena cava there is another blood vessel opening.
Insert a GREEN COLORED PENCIL into this; it should also lead into the right atrium. This is the
inferior vena cava, which brings blood from the lower tissues.
8) You can also see another blood vessel next to the left auricle. This is a pulmonary vein that
brings blood from the lungs into the left atrium. Put a RED COLORED PENCIL in this.
9) Sticking straight up from the center of the heart is the largest blood vessel you will see. This is
the aorta, which takes oxygenated blood from the left ventricle to the rest of the body (the
ventricles are the lower chambers of the heart). Put a YELLOW COLORED PENCIL into the
aorta.
10) Behind and to the left of the aorta there is another large vessel. This is the pulmonary
artery which takes blood from the right ventricle to the lungs. Put a BLACK COLORED
PENCIL into this artery.
Use colored pencils as shown above to mark the
chambers. See below for colors.
Pulmonary Vein – red
Pulmonary trunk/artery – black
Aorta - yellow
Superior Vena Cava – blue
Inferior Vena Cava – green
Procedure - Internal Anatomy
ASK THE WRITER TO FIND THE
LOOKING FOR!
ON THE LAB SHEET SO YOU KNOW WHAT YOU ARE
1) 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.)
2) With your GLOVED fingers, push open the heart at the cut to examine the internal structure. If
there is dried blood inside the chambers, rinse out the heart.
3) Locate the right atrium. Notice the thinner muscular wall of this receiving chamber. Find where the
inferior and superior vena cavae enter this chamber and notice the lack of valves.
4) Locate the valve that is between the right atrium and right ventricle. This is called the tricuspid
valve. The valve consists of three leaflets and has long fibers of connective tissue called chordae
tendinae that attach it to papillary muscles of the heart. The papillary muscles are located in the
ventricles contracting to keep the valves from loosening when they should be tightly closed. The
tricuspid valve allows blood flow from the right atrium into the right ventricle during diastole (period
when the heart is relaxed). When the heart begins to contract (systole phase), ventricular pressure
increases until it is greater than the pressure in the atrium causing the tricuspid to snap closed.
Tricuspid Valve
1) Use your GLOVED 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.
2) Find the septum on the right side of the right ventricle. This thick muscular wall separates the right
& left pumping ventricles from each other and prevents the mixing of deoxygenated blood with
oxygenated blood.
3) 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.
4) 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 toward the apex to the septum at the center groove. Push
open the heart at this cut with your GLOVED fingers and rinse out any dried blood with water.
5) Examine the left atrium. Find the openings of the pulmonary veins from the lungs. Observe the
one-way, semi-lunar valves at the entrance to these veins.
6) 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
& blood flows from the left atrium into the left ventricle during diastole.
7) Examine the left ventricle (remember it is on your right side). Notice the thickness of the ventricular
wall. This heart chamber is responsible for pumping blood throughout the body.
8) Using your scissors, cut across the left ventricle toward the aorta & continue cutting to expose the
valve. 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.
9) 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.
When you have finished dissecting the heart, clean up as follows:
 dispose of the heart in the assigned bag
 clean all dissection equipment and pan and the lab tray with hot soapy water. Dry everything
well and return all dissecting equipment to the appropriate area.
 Using surface spray, clean your lab table thoroughly.
 Wash your hands thoroughly with soap.
 THEN answer all questions on your lab report.
Heart Dissection Lab Sheet
NAMES: ________________________________________
1. How can you tell which side of the heart is the ventral surface?
2. How many chambers are found in the mammalian heart? _________ Research what other organisms
(besides mammals) have this many chambered-hearts.
3. RESEARCH: What is the advantage in having this number of chambers compared to organisms with a
fewer number of chambers?
Checkpoint: SHOW YOUR TEACHER.
superior vena cava
inferior vena cava
aorta
left atrium & ventricle
right atrium and ventricle
pulmonary artery
auricle
apex
pulmonary veins
coronary arteries & veins
4. Which chambers are the blood-pumping chambers of the heart?_________________________
5. Which chambers are the blood-receiving chambers of the heart?__________________________
6. How do the walls of the atria compare with the walls of the ventricles and why are they different?
7. Differentiate between heart systole and diastole.
8. What is the purpose of heart valves?
9. True or false? The vena cavae do not have valves. ____________________
10. Name all the valves found in the heart and what they are between.
Checkpoint: SHOW YOUR TEACHER.
cordae tedinae
septum
aortic valve
tricuspid valve
coronary sinus
11. Vessels that carry blood away from the heart are called __________________, while
__________________ carry blood toward the heart.
12. Which artery is the largest and why?
13. RESEARCH: What is the purpose of the coronary artery and what results if there is blockage in this
vessel?
14. Find the bolded and underlined heart structures throughout the lab procedures and match them up to
their functions/descriptions outlined below:
a) Major blood vessel that supplies blood to the body ________________________________________
b) Thin membrane that surrounds heart and anchors it ________________________________________
c) Supplies fresh blood with oxygen and nutrients to the heart muscle itself ______________________
d) Returns oxygenated blood from the lungs to the left atrium ______________________________________
e) The muscle of the heart ________________________________________________________
f) Carries blood to the lungs to receive oxygen and can be found curving out of the right ventricle
________________________________________________________
g) The tip of the heart ________________________________________________________
h) The thick muscular wall that separates the right and left pumping ventricles from each other
________________________________________________________
i)
What muscles hold the valves in place? _______________________________________________________
j)
What is another name for the bicuspid valve? _________________________________________________
k) What are the flaps on the front of the atria called? ______________________________________________
l)
If you place a probe in the aorta, into what chamber will it exit? ______________________________
m) The superior and inferior vena cava enter into what chamber of the heart? _______________________
n)
What are the tendons that connect the valves to the muscles? __________________________________
o) What is the only artery in the body that carries deoxygenated blood? _________________________
15. Label the diagram below. #9 is the papillary muscle (hard to see).