Sheep Heart Dissection

ObjectivesBy the end of this lesson, students will be able

to:• Demonstrate proper dissection safety

techniques• Identify the right and left sides of the heart• Identify the parts of the heart: auricles,

superior vena cava, pulmonary vein, aorta, left ventricle, pulmonary artery, bicuspid and tricuspid valve.

• Measure the diameter of the aorta, pulmonary trunk, left atrium, left ventricle and right ventricle.

• Compare and contrast the structure of a sheep heart to a human heart

Arkansas Frameworks

Grade 6 Grade 7 Grade 8

LS.2.6.1 LS.7.1.2 LS.8.1.8

LS.2.6.2 LS.7.1.3

LS.2.6.3 LS.7.1.4

LS.2.6.4

LS.2.6.6

Why Dissect?Dissection allows students to:• Practice safety procedures• Construct science process skills• Organize the hierarchal

relationships of tissues, organs, organ systems and organisms

• Compare similarities and differences among organisms

• Connect organism complexity to its diversity

Materials• Sheep heart specimen• Dissection tray or

Styrofoam meat tray• Dissection kit with

scissors, pins, scalpels, tweezers and probes

• Gloves• Goggles• Plastic aprons• Student worksheets

General Safety Rules

• The classroom should be well ventilated

• Work space should be flat and free of unnecessary materials

• All equipment should be clean and unbroken

• ABSOLUTELY no eating, drinking or gum chewing during dissection activities

Sharp Instrument Safety

• Prepare a container for disposal of broken instruments or glassware

• Dispose of the container intact and replace with a new one to prevent others from being cut

• Inventory all sharp items to ensure all objects remain in the classroom

• Ensure that students use sharp instruments properly.

• Remind students they should always cut away from themselves and others

Before we proceed

While dissecting, be respectful of your lab partners and of the specimen you are about to explore, observe and learn from.

Take extra care with your dissection tools. Your scissors are your most important tool, but be sure to handle them carefully and always double check before cutting.

If you have any questions, please ask.

Attire• Wear Gloves• Wear Aprons• Wear Goggles (ANSI

Z87.1)

Always!! No Exceptions!!!!

Interesting Facts Sheep have a four chambered heart, just like you. By studying the anatomy of a sheep’s heart, you can learn about how your own heart pumps blood through your body and keeps you alive.

Interesting Facts • 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.

Right Side

Left Side

External Anatomy• Identify the right and left sides of

the heart. On one side of the heart 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. Right

Side Left SideApex

External Anatomy• 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.

Auricle

External Anatomy• Find the large opening

at the top of the heart next to the right auricle.

• This is the opening to the superior vena cava.

• Stick a probe down the vessel. You should feel it open into the right atrium.

Superior Vena Cava

Auricle

External Anatomy• 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 to the right atrium. This is the inferior vena cava.

Superior Vena Cava

Inferior Vena Cava

Inferior Vena Cava

External Anatomy• You can also see

another blood vessel next to the left auricle. This is the pulmonary vein.

Pulmonary Vein

Superior Vena Cava

Inferior Vena Cava

External Anatomy• Sticking straight up

from the center of the heart is the largest blood vessel you will see. This is the aorta. The aorta takes oxygenated blood from the left ventricle to the rest of the body.

Left Ventricle

Aorta

External Anatomy• Behind and to

the left of the aorta there is another large vessel. This is the pulmonary artery.

Pulmonary Artery

Incision 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 picture.

Moderator Band

Chordae Tendinae

Tricuspid Valve

Papillary Muscle

Incision 2• Insert your probe

into the pulmonary artery and see it come through the right ventricle. Make an incision down through this artery.

Pulmonary Artery

Pulmonary Semilunar

Valve

Observe and Measure

• Observe the right half of the heart. • Identify the following:

– Tricuspid valve– Pulmonary semilunar valve– Papillary muscles– Chordae Tendinae

• Measure the following:– Diameter of the right atrium and

ventricle– Wall thickness of the right atrium

and ventricle– Diameter of the aorta and

pulmonary trunk

Incision 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 line.

Chordae Tendinae Bicuspid

Valve

Papillary Muscle

Incision 4• Insert a probe

into the aorta and observe where it connects to the left ventricle. Make an incision up through the aorta.

Observation• Observe the left side of

the heart.• Identify the following:

– Mitral or Bicuspid valve– Aortic Semilunar valve– Papillary muscles– Chordae tendinae

• Measure the following:– Diameter of the left

atrium and ventricle– Wall thickness of the left

atrium and ventricle.

Clean Up• Place all dissecting specimens and

parts into approved container provided by the instructor.

• Wash dissecting equipment and trays in dilute bleach solution provided by the instructor.

• Dry equipment thoroughly to prevent rusting.

• Clean table tops with dilute bleach solution provided by the instructor.

• Wash hands thoroughly before leaving the classroom.

ResourcesColor Me Heartwww.childrenheartinstitute.org/kidsonly/heartflw.htmHeart Housewww.childrenheartinstitute.org/kidsonly/hearthse.htmHeart Dissection Labwww.hometrainingtools.com/articles/

heart-dissection-project.htmlHeart Anatomywww.enchantedlearning.com/subjects/

anatomy/heart labelinterior/label.shtml

ResourcesHeart Lessonshttp://www.smmm.org/heart/

lessons/heartDiagram.htmAnimations/Interactiveshttp://www.smm.org/heart/heart/

top.htmlHeart Diagramhttp://classroom.kidshealth.org/

classroom/6yo8/body/systems/cardiovascular_handout1.pdf

Color Heart Diagramwww.heartfoundation.org.au/

document/NHF/heartimage.pdf