When Kat and I were learning about the heart and cardiovascular system, we really wanted to get an in depth understanding about the human heart and how it works. We had built a model of a pump to mimic a heart, we had made up a circulation game with little blood cell pieces, and we had even made an anatomically correct model of the human heart! What we hadn't done, was look at a real heart, in the flesh, and see how we we learned looked in reality.
For this, we turned to the tried and true method of biological dissection! A biological dissection is a very detailed examination of a deceased (and sometimes preserved) plant or animal. It often involves cutting it open at specific points to get a good look at the inner workings of the organism. Kat is no stranger to doing dissections, as she did her first when she was four years old. She had found a giant crab spider that had perished in our office and wanted to take a look at it. She actually made a fascinating discovery, that spiders have almost metallic looking springs loaded in their pedipalps (pads on their front two legs) that they use in mating!
|Kat's crab spider dissection, featured in|
The Not So Creepy Crawlies
From then on, she had taken just about every dead insect she could find to dissect! She wanted to know if all of the parts on the inside were the same, and what they were for. As we later learned about the anatomy of mammals, she wanted to know why the parts were different for insects and other animals! She's always been wanting to take a deeper look. Sometimes, facilitating this desire has made me pause to take a deep breath, as the dissections get more and more involved.
In the case of the bat dissection, it was the first time I had any hesitation. I didn't let her on to it, as I wanted her to fully experience and explore her curiosity without adopting my opinion of it. It was, admittedly, a bit difficult at first, to watch her cut open a cute little bat specimen. However, she loved it, and was absolutely fascinated by how everything inside the bat matched what she had seen in pictures of our own anatomy! She could see the lungs, the heart, the intestines, everything! It was all right there, opened up in this world of biological wonder to a little girl.
|Kat participating in a bat dissection.|
Featured in Dissection at the Science Center!
I ordered a pig heart from Carolina Biological Supply Company. For only $10.00, this kit came with the heart, a teacher and student guide, a dissection tray, scissors, magnifying glass, forceps (similar to giant plastic tweezers), a ruler, probe, and safety goggles! It had just about everything we needed to do our dissection! We had some disposable scalpels on hand in the house, so we added those to our kit and we were ready to go!
|This was one of the best packages EVER to come in the mail!|
|Bev Tryk The Science Chick|
|Science: It's serious business.|
When we learned about the intricacies of how the heart works to pull the valves open to pump blood out, we of course wanted to check out the valve to see what it actually looked like! Kat cut right into the left atrium on her quest to find the valve. With some help with Beverly (again, those muscles are thick!), we were finally able to get it open.
|Tricuspid Valves open to let blood through, then immediately close to|
prevent back flow.
This is an auricle, and it sits on top of the left atrium, collecting oxygenated blood as it leaves the lungs, before depositing it in the ventricle so it can continue its cycle through the heart and body! All of that mass of tissue is normally filled with the oxygen rich blood our bodies need to function properly. There is an auricle on the other side of the heart as well. The right auricle fills with deoxygenated blood, before dropping it off into the right ventricle so it can be pumped back into the lungs to collect more oxygen.
One of the coolest things we found while we were dissecting the heart, was that the heart is filled with so many nerve cells! Some of them are large enough that you can actually see them! We cut open the aorta, so we could see what the tissues looked like inside the largest artery in the body. What we found were regularly spaced bundles of nerve cells!
For me personally, this was the most exciting part of our heart dissection. There were real bundles of nerves, right there! In hindsight, I really should have sliced a sample of nerve cells to look at under the microscope. I'm going to have to keep an eye out for another heart dissection (perhaps at our Arizona Science Center), and see if I can snag a sample. I did, however, manage to slice off portions of the heart muscles, so we could take a look at these under the microscope! I had almost purchased my own set of prepared heart muscle slides, but decided to try to make my own instead. Not only was it very easy to do (you just slice VERY thin pieces of the tissue), but the clarity was fantastic!
Doing a heart dissection was such a fantastic way to really gain insight into the inner workings of the heart. We had spent so much time learning about it, making our models, and drawing diagrams, but really getting to look at how it all connected together in the flesh, made our understanding of it that much greater. Being able to conduct our dissection under the tutelage of our wonderful friend and certified EMT, Beverly Tryk, made the experience all the more incredible, as every question could be answered with precise detail right then and there!
|Labeled with insect pins and index cards, here are the major components of the heart!|
|Look Mom! It's the aorta!|
We bought our dissection kit from Carolina Biological Supply. This company has several dissection kits that are under or around $10 and come with everything you need to do your dissection! The specimens are preserved using their special "Caro fluid" which does not use formaldehyde. On a personal note, I HIGHLY recommend going through them, as their selection is huge and low priced, their service is prompt, their customer service is responsive, and their teaching materials have been trusted by science institutions for many years.