Download mammalian heart dissection - Tamalpais Union High School District

Physiology 2
Name
Redwood High School
Class Period
2/17
The Cardiovascular System: Anatomy of a Mammalian Heart
Background
The human heart is the muscular pump of the cardiovascular system. The rhythmic contractions of the
cardiac cycle produce the pressure responsible for arterial circulation, which delivers blood and oxygen to body
tissues. The pump is composed of four (4) hollow chambers. The two right-side chambers relate to the lungs and
are responsible for the pulmonary circulation. Deoxygenated blood from the body enters the right atrium and is
pumped to the lungs, under relatively low pressure, by the right ventricle. The two left-side chambers relate to
the rest of the body and are responsible for systemic circulation. Oxygenated blood returns, from the lungs, to
the left atrium and is pumped to the body tissues by the left ventricle, under rather high pressure. The cardiac
valves regulate this one-way flow of blood. The bi- and tri-cuspid valves prevent backflow between atria and
ventricles, while the semi-lunar valves prevent reflux between the right ventricle and pulmonary artery and the
left ventricle and aorta.
The human heart displays the four chambered structure which is typical of birds and mammals, and
serves to effectively separate oxygenated and deoxygenated blood. This separation ensures that body cells of
these endothermic organisms will receive a maximal amount of oxygen with each cardiac cycle. The large
oxygen requirement is necessary to produce the energy needed by warm-blooded organisms. These structural
similarities allows us to use a non-human, mammalian heart– from a pig– to directly study the anatomy of the
human heart.
Focus Questions
•
What are the structural similarities shared by all mammalian hearts?
•
What are the structural differences between arterial and venous connections to the mammalian heart?
•
What are the structural differences between right and left sides of the mammalian heart?
•
What are the structural differences between atria and ventricles of the mammalian heart?
•
What are the structural differences between mammalian heart valves?
Procedure
Part A. External Anatomy
1. Obtain a dissecting tray, and a pig heart. Dip the heart in the provided warm water bath. This
should remove any excess blood.
2. Place the heart in a dissecting tray with the ventral side up. Look closely on one side for a
diagonal line of blood vessels that divide the heart. The half that includes the apex (pointed end)
of the heart is the left side.
3. Identify and closely observe the chambers of the heart from an external view.
4. Identify and closely observe the blood vessels which enter and leave the heart: aorta, vena cava
(inferior and superior), pulmonary arteries and pulmonary veins. For a better view, you may
need to remove the connective tissue around the pulmonary arteries and aorta.
5. Use your finger or a blunt probe to follow the vessels into their respective heart chambers.
Recall: The inferior and superior vena cava empty into the right atrium. The aorta takes
oxygenated blood from the left ventricle to the rest of the body. The pulmonary arteries and
veins transport blood between the heart and lungs.
6.
Locate all of the coronary arteries and follow, as much as is possible, the path of cardiac
circulation. Probe the coronary arteries. Create Drawing #1. Complete Measurements and
Written Descriptions.
Data Collection – Record all data on Student Data handout.
 Drawing #1. Make a detailed, scaled and labeled drawing of the external view of the heart.
Label the following structures: right atrium, left atrium, right ventricle, left ventricle, aorta,
vena cava (inferior and superior), pulmonary artery, pulmonary vein and coronary arteries.
 Measurements. Conduct and record the following measurements: aortic diameter (mm);
thickness of aortic wall (mm); vena cava diameter (mm); thickness of vena cava wall (mm).
 Written Descriptions. Record a set a written observations on the following 'great vessels' of the
heart: aorta; vena cava (inferior and superior); pulmonary artery and pulmonary vein. Focus
on the differences between arteries and veins, as well as the specific connections between
vessels and heart chambers. Feel free to support your written observations with appropriate,
labeled diagrams.
Part B. Internal Anatomy and Dissection Procedures
1. Locate the superior vena cava. 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.
2. Pull the two sides apart and look for 3 flaps of membrane that form the tricuspid valve between
the right atrium and the right ventricle to the apex.
4. Locate and observe the chordae tendinae and the papillary muscles.
5. Insert your probe into the pulmonary artery and watch it come through to the right ventricle.
Make an incision down through this artery and look inside for three membranous pockets that
form the pulmonary semilunar valve. This valve prevents blood from flowing back into the right
ventricle. Create Drawing #2.
6. 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 to the apex. Locate the mitral
(bicuspid) valve between the left atrium and left ventricle.
7. Insert a probe into the aorta and obsere where it connects to the left ventricle. Make an incision
up through the aorta and examine the inside carefully for three membranous pockets that form
the aortic semilunar valve. This valve prevents blood from blowing back into the left ventricle.
Create Drawing #3. Complete Measurements and Written Descriptions.
8. Return the heart, any leftover pieces and your rubber gloves to the storage bag for disposal.
Wash and dry your dissecting equipment. Thoroughly wash your hands.
Data Collection – Record all data on Student Data handout.
 Drawing #2. Make a detailed, scaled and labeled drawing of the internal view of the heart.
Label relevant chambers and valves, along with chordae tendinae and the papillary muscles.
 Measurements. Conduct and record the following measurements: thickness of right atria wall
(mm); thickness of left atria wall (mm); thickness of right ventricle wall (mm); thickness of left
ventricle wall (mm).
 Written Descriptions. Record a set a written observations on the following heart valves:
tricuspid valve, bicuspid valve, aortic semilunar valve and pulmonary semilunar valve. Focus
on the differences between the valves, as well as the specific connections between valves,
vessels and heart chambers. Feel free to support your written observations with appropriate,
labeled diagrams.