Download lab practice: dissecting a cow`s heart

E=
/6
The Victoria School
MYP Year 3
February 22nd 2013
LAB PRACTICE: DISSECTING A COW’S HEART
Criterion Evaluated: E
ATL: Thinking. Applying knowledge and concepts, including logical progression of arguments.
The purpose of this activity is:


Identify and compare the size, shape and tissue type of the mayor anatomic landmarks of the heart
Associate the heart’s structure with its function.
Materials
Dissection kit
Rubber/latex gloves
Cow Heart
Labelled pins
Pencils
Dissection guide and results table
Diagram of heart
Digital camera or cell phone with camera
PROCEDURE (during the lab practice)
SAFETY

Take care with sharp dissecting tools and report any cuts to your teacher.

Do not play with any of the materials you are given.

At the end of the practical, disinfect the work area and wash your hands thoroughly using soap and plenty of
water.
LAB PRACTICE
This lab practical allows you to identify and compare the size, shape and tissue type of the major chambers and
vessels of the heart. The goal of the lab is not, however, just to observe anatomy, but to associate structure with
function. The heart is a pump for blood that comes into the right atrium, goes out to the lungs through the right
ventricle, returns through the left atrium, and leaves again through the left ventricle. Each chamber is separated by
valves that prevent the backflow of blood. Try and figure out where the various components are, how each works,
especially how the shape, composition, and even texture of each part contribute to its function.
a
b
Check the look, feel and color of the heart.
First, identify the right side and left side 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).
c
d
e
f
g
h
i
Label the external parts of the heart with the pins given:
i.
Right atrium and left atrium (if possible)
ii.
Right and left ventricle (lower chambers of the heart)
iii.
Coronary artery and vein (the diagonal line of blood vessels that divide the heart)
iv.
Aorta (artery leaving from the left side of the heart)
v.
Pulmonary artery (artery leaving from the right side of the heart)
vi.
Vena cava and Pulmonary vein (if possible)
Take a picture of your labeled heart with the pins. Print this for your guide.
Locate the right atrium and make an incision down through the wall of the right ventricle.
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 "heartstrings."
Make an incision down through the pulmonary 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.
Insert your dissecting scissors or scalpel into the left atrium 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.
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.
Aorta
The two vena cava go into the right
atrium on the other (dorsal) side
Pulmonary artery
The pulmonary vein goes into the left
atrium on the dorsal side.
Coronary artery and vein
When you need to see inside the right
ventricle, cut here.
When you want to open the left
ventricle cut here.
QUESTIONS (to solve AFTER the lab practice)
1. What do these structures look like? Complete the table.
Structure
Observations (color, texture, and thickness of the wall)
Aorta
Right and left
atrium
Right
Ventricle
Left Ventricle
Pulmonary
Artery
2. Include a drawing of the following:
Membranous pockets of the pulmonary artery
Mitral valve (or bicuspid valve) that separates the
left atrium and the left ventricle.
3. How are the walls of the left ventricle different from the walls of the right ventricle?
……………………………………………………………………………………………..
4. Cow’s Heart labeled (picture taken in the lab):