Download Sheep Heart Dissection The laboratory sheet Objective: In this

Sheep Heart Dissection
The laboratory sheet
Objective:
In this exercise, you will:
1. Examine, identify, and learn the functions of the exterior and interior
anatomy of the heart
2. Trace the pathway of blood through the heart, pulmonary and systemic
systems
3. Follow the events in the heart as it pumps
Vocabulary:
atrium
ventricle
coronary artery
vein
artery
Websites to have open to lend a helping hand:
National Geographic - the human body - heart
(http://science.nationalgeographic.com/science/health-and-human-body/humanbody/heart-article.html) - this site will help with finding out the functions of
all the parts and to see what a human heart would look like.
ZeroBiology Sheep Heart Dissection video
(http://www.zerobio.com/videos/sheep_heart_anatomy.html) - a good video that shows
what the parts actually look like in the heart
GWC Maricopa (http://www.gwc.maricopa.edu/class/bio202/heart/anthrt.htm) - This
site is good for labeling the interior and exterior of the heart
Home Science Tools (http://www.hometrainingtools.com/heart-dissectionproject/a/1318/) - this site is where these directions came from. You can click on
the images for a much larger and clearer picture.
NOVA Map of the Human Heart (http://www.pbs.org/wgbh/nova/body/map-humanheart.html) - this one is great at showing the flow of blood through the heart. it
also does a good job labeling some of the structures.
Procedures:
As you move your way through this laboratory, make sure to
label the heart on your data page and fill in the functions
and descriptions of the parts that you are seeing.
Observation: External Anatomy
Most heart diagrams show the left atrium and ventricle on the right side of the diagram. Imagine the
heart in the body of a person facing you. The left side of their heart is on their left, but since you are
facing them, it is on your right.
1. 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. 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.)
2. Turn the heart so that the right side is on your right, as if it were
in your body. Examine the flaps of darker tissue on the top of the
heart. These ear-like flaps are called auricles. Find the large
opening at the top of the heart next to the right auricle. This is the
opening to 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 probe down this vessel. You should
feel it open into the right atrium. A little down and to the left of the
superior vena cava there is another blood vessel opening. Insert
your probe into this; it should also lead into the right atrium. This is
the inferior vena cava, which brings blood from the lower tissues. 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.
3. 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). The aorta branches into more than one artery right after it leaves the
heart, so it may have more than one opening on your heart specimen. Look carefully at the openings
and you should be able to see that they are connected to each other.
4. 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.
Dissection: Internal Anatomy
1. Insert your dissecting scissors or scalpel into the superior vena
cava and make an incision down through the wall of the right
atrium and ventricle, as shown by the dotted line in the external
heart picture. Pull the two sides apart and look for three flaps of
membrane. These membranes form the tricuspid valve between
the right atrium and the right ventricle. The membranes are
connected to flaps of muscle called the papillary muscles by
tendons called the chordae tendinae or "heartstrings." This valve
allows blood to enter the ventricle from the atrium, but prevents
backflow from the ventricle into the atrium.
2. Insert your probe into the pulmonary artery and see it come
through to the right ventricle. Make an incision down through this
artery and look inside it for three small membranous pockets.
These form the pulmonary semilunar valve which prevents
blood from flowing back into the right ventricle.
3. Insert your dissecting scissors or scalpel into the left auricle at
the base of the aorta and make an incision down through the wall
of the left atrium and ventricle, as shown by the dotted line in the
external heart picture. Locate the mitral valve (or bicuspid valve)
between the left atrium and ventricle. This will have two flaps of
membrane connected to papillary muscles by tendons.
4. Insert a probe into the aorta and observe where it connects to the
left ventricle. Make an incision up through the aorta and examine
the inside carefully for three small membranous pockets. These
form the aortic semilunar valve which prevents blood from
flowing back into the left ventricle.
Blood Flow
Using the National Geographic website and the Nova Map of the Human Heart interactive, trace the
flow of blood through the heart picture. Use a blue marker for deoxygenated blood and a red marker for
oxygenated blood.
Pumping Action of the Heart
1. Blood enters the top two chambers of the heart. Because they are made of muscle, they are able to
squeeze together or contract. When this happens, blood is pumped to the two bottom chambers which
are relaxed. These events are shown in Figure 4. Note that certain valves in Figure 4 are open while
other valves are closed. Complete the first column of Table 2 on your Data Sheet.
2. Once blood fills the two bottom chambers they contract. Blood is then pumped out of the heart into
the rest of the body. These events are shown in Figure 5. Note which valves are open or closed in
Figure 5. Complete the second column of Table 2.
Data:
You shall record your data on the data sheet given with this, or on your own
paper.
Analysis questions:
1. What is the job of the coronary artery?
2. Blood is pumped from the heart to the body through the aorta.
a. Which chamber does this job?
b. Does this blood have more oxygen or more carbon dioxide?
c. Which valves are open during this process?
3. Blood is pumped from the heart to the lungs through the pulmonary artery.
a. Which chamber does this job?
b. Does this blood have more oxygen or more carbon dioxide?
c. Which valves are open during this process?
4.Trace a drop of blood through the heart by putting these heart chambers, valves
and external places in proper order: left atrium, aortic valve, pulmonary valve,
right atrium, right ventricle, left ventricle, bicuspid valve (mitral valve),
tricuspid valve, lungs, and body. Start with the Right atrium.
Conclusion:
Explain how the anatomy of the heart helps keep it efficient. Think about the blood
oxygen levels and where the blood is going and tie that to the number of chambers.
Also discuss the reasons for difference in the thickness of the ventricle chamber
walls.
Error:
Don't forget to mention if anything went slightly different than the laboratory
wanted it to.
Sheep Heart Dissection
Partners:
___________________
Computer Guru_____________________________
Period __________________
Scribe ______________________________________
Surgeon ____________________________________
Date:
Don't forget to write up your own laboratory report. The data
sheet will be only attached to one persons report, so record in
your data section who the lucky person was that got to keep it.
Data:
Table 1: Anatomy of the Heart
Structure
Aorta
Pulmonary
Artery
Pulmonary
Vein
Coronary
Arteries
Superior
Vena Cava
Inferior
Vena Cava
Left Atrium
Right
Atrium
Left
Ventricle
Right
Ventricle
Function
Description
Pulmonary
Valve
(semilunar
valve)
Aortic
Valve
(semilunar
valve)
Bicuspid
(mitral)
Valve
Tricuspid
Valve
Table 2:
The opening and closing of parts of the heart
Blood entering
Blood leaving
ventricles
ventricles
The atria relaxed or
contracted?
The ventricles relaxed or
contracted?
Semilunar valves open or
closed?
Bicuspid valve opened or
closed?
Tricuspid valve opened or
closed?
Heart Diagram:
Label the following heart diagram and use blue and red markers to
show the direction of blood flow.
Credits: This laboratory report has elements taken from the following locations.
What is not from there is from my mind.
National Geographic (http://science.nationalgeographic.com/science/health-and-humanbody/human-body/heart-article.html)
Home Science Tools (http://www.hometrainingtools.com/heart-dissectionproject/a/1318/))
Biology an everyday experience - Glencoe/McGraw Hill