“Don’t Break My Heart, My Achy Breaky Heart” Heart Dissection Walk Through

Step 1 – What to Expect When you First See the Heart When you first obtain your heart, you will see a lot of white fatty tissue surrounding it. It is usually a waste of time to try to remove this tissue. a lot of tiny blood vessels on the outside of the heart (these feed the tissue of the heart – remember the heart itself needs oxygen too!) a shape you may not expect – often the packaging and preserving process can cause this How will you know which side is front, back, right, left? The front side of the heart curves; the backside is flatter. The front has a couple of key features: 1) a large pulmonary artery that extends off the top 2) the flaps of the auricles covering the top of the both of the 2 atria (upper chambers)

Remember that if you are looking at the back of the heart, then the right and left sides are the same as your right and left hand. Front Side of Heart Back Side of Heart

Step 2 - Supplies You Will Be Given BEFORE - Prepare the Area newspapers DURING - To Dissect ProbesScissorsBlades DURING - To mark specific structures PencilsWool AFTER - Clean-Up Paper Towel Gloves Lab Questions (pre-read them so you are prepared)

Step 3 – Locate the 4 Main Vessels (2 arteries, 2 veins) Use your fingers to probe around the top of the heart. Four major vessels can be found entering the heart: Two arteries Pulmonary artery (from __________) (aorta is a little behind it) Aorta (from _________) Two veins Superior vena cava (from _____________) Pulmonary vein (from _______________)

Aorta Pulmonary Artery

Aorta *may be covered by fat, so use your fingers to poke around until you find the opening. Push your finger all the way in the aorta and you will feel inside of the left ventricle. The left ventricle has a very thick wall, unlike the right ventricle. Why do you think this is so? _________________________ Insert your finger through the pulmonary vessel to feel the left ventricle and you will notice and feel that it is much thinner than the left side of the heart. With your fingers or probes in the aorta and the pulmonary artery you should notice that they criss-cross each other, with the pulmonary artery in the front.

Step 3 – 2 Major Veins The two major veins that enter the heart can be found on the backside because both enter the atria. On the left side, you should be able to find the opening of the pulmonary vein as it enters the left atrium. The superior vena cava enters the right atrium. In many preserved hearts, the heart was cut at these points, so you won't see the vessels themselves, you will just find the openings. Again, use your fingers to feel around the heart to find the openings. Aorta Pulmonary Artery Pulmonary Vein Superior Vema Cava

Step 5 – Make the Incision Now that you have all of the vessels located and marked, you can now open the heart to view the inner chambers. Use the superior vena cava and pulmonary vein as guides for where to cut. You are basically going to be cutting each side of the heart so that you can look inside.

The heart below is marked to show you where the two incisions should be made. STEP ONE STEP TWO

Step 6 – Viewing the 4 Chambers At this point it is helpful to have 2 hands one hand holds the heart apart so you can take a peek inside one hand to use a probe to locate the specific parts Your colored pencils you used to mark the heart in step 2 can also now be used to see where those vessels connect within the heart. Example: the aorta pencil can now be seen ending in the left ventricle. You can also now see how much thicker the walls of the left ventricle are compared to the right ventricle.

Step 7 -Other Obvious Structures *chordae tendinae These tendons hold the heart valves in place, sometimes they are called the "heartstrings". When someone is attracted to someone else we can say “They are pulling on your heartstrings” *valves *were probably cut when the heart was opened, but if you follow the "cords" they should lead you to a thin flap of skin that opens and closes to let blood in/out of the heart *atrioventricular (bicuspid) valve (left side) *tricuspid valve (right side)

Step 8– Trace the Path of the Blood Using wool trace the path of blood from the right atrium to the left ventricle. Superior Vena Cava (vein from body) Right atrium Left atrium Pulmonary Artery Pulmonary Veins Left Atrium Left Ventricle Aorta (artery to the body) DID YOU SUCCEED?

Step 9 – Clean-Up Clean up Newspaper, paper towel, wool -- garbage. Wash and dry scissors, probes, blades, pencils Wipe the table area. Rinse. Repeat until there is no streaking. Return the dissection tray to the area indicated. Lab Summary sheet to be completed and turned in.

Plux Demo (trachea, heart, lungs) Identify the *trachea *bronchi *bronchiole tubes (if visible) *alveoli Touch the lungs of the pig and think about how they feel What do you think will happen to the lungs if the teacher were to blow air into the trachea?