Sheep Heart Dissection

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Sheep Heart Dissection
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Objectives

• By 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

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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
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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

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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

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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

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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

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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.

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Attire

• Wear Gloves
• Wear Aprons
• Wear Goggles (ANSI Z87.1)
• Always!! No Exceptions!!!!

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Interesting Facts

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

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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
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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 Side
Apex
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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
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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
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External Anatomy
Superior Vena Cava

• 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.

Inferior Vena Cava
Inferior Vena Cava
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External Anatomy
Inferior Vena Cava

• You can also see another blood vessel next to the
  left auricle. This is the pulmonary vein.

Superior Vena Cava
Pulmonary Vein
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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.

Aorta
Left Ventricle
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External Anatomy

• Behind and to the left of the aorta there is
  another large vessel. This is the pulmonary
  artery.

Pulmonary Artery
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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.

Chordae Tendinae
Papillary Muscle
Tricuspid Valve
Moderator Band
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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 Semilunar Valve
Pulmonary Artery
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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

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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
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Incision 4

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

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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.

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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.

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Resources

• Color Me Heart
• www.childrenheartinstitute.org/kidsonly/heartflw.h
  tm
• Heart House
• www.childrenheartinstitute.org/kidsonly/hearthse.h
  tm
• Heart Dissection Lab
• www.hometrainingtools.com/articles/heart-dissectio
  n-project.html
• Heart Anatomy
• www.enchantedlearning.com/subjects/anatomy/heart
  labelinterior/label.shtml

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Resources

• Heart Lessons
• http//www.smmm.org/heart/lessons/heartDiagram.htm
  
• Animations/Interactives
• http//www.smm.org/heart/heart/top.html
• Heart Diagram
• http//classroom.kidshealth.org/classroom/6yo8/bod
  y/systems/cardiovascular_handout1.pdf
• Color Heart Diagram
• www.heartfoundation.org.au/document/NHF/heartimage
  .pdf