The Flubbery Eye

For my last blog, I will discuss the eye and then give you more information for continuing your cat dissections. Because the cat has such a small eye, our class uses a cow’s eye in order to see all the different parts.
The eye is an amazing organ that consists of a very complex structure. When we were first given the eye we were a little grossed out. Looking down at an unmoving eye with eyelashes still attached is a little unnerving. We began by making a small incision on the side of the eye with a scalpel. As the pressure of the knife pierced the thick wall of the eye, the change in pressure caused a release of aqueous humor, the watery substance that helps maintain the shape of the eye. As the aqueous humor dribbled out, we continued to cut the skin of the eye, making a complete circle. Once the two sections were separated, we began looking at the side with the lens. We noticed that the solution became thicker; the consistency was between jello and water. The more gel like solution is called vitreous humor. It felt cold and slid between my fingers as I removed it. The slime looked almost like a clear version of flubber.

The lens is directly behind the colored part of the eye and looks like the inside of a white jellybean that someone had sucked the harder sugar covering off of. It is surrounded by the dark capillary bed that gives the eye its needed nutrients. On the opposite side of the eye is retina, a delicate membrane overlying the darkly pigmented choroid coat.

Want more info on the urinary system?

Want more info on the brain? (point and click to see all the different area’s!)

Mysteries of the Heart

Today, we began the circulatory system, by far the most confusing. Because the heart has a confusing pathway, I decided to write a description of how the blood flows from the heart to the lungs to the rest of the body. Also, the following are helpful examples if you are more of a visual learner!

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The circulatory system is a system that brings freshly-oxygenated blood to all the tissues and organs of the body. When the heart contracts it causes a forceful tightening of the myocardium that pushes blood out into two major loops. The systemic loop brings oxygen to the organs, structures and tissues and collects carbon dioxide which much be removed from the body. The systemic loop carries oxygen fresh blood from the lungs that enters the superior left chamber of the heart; this is known as the left atrium. From here, the blood is forced, by contraction, through the bicuspid valve into the left ventricle. When the left ventricle contracts during a heartbeat, the blood on the left side is forced through the aortic semi-lunar valve into the aorta. The aorta sends oxygen-rich blood to every part of the body except the lungs. Because the body has an extensive amount of arteries and capillaries the left ventricle must produce a large enough contraction to give the blood enough pressure to make it to all the capillaries throughout the body and then back to the heart. This explains why the wall or myocardium of the left ventricle is much thicker than the right ventricle.



The pulmonary loop carries blood to and from the lungs and releases the carbon dioxide while picking up fresh oxygen. The pulmonary loop is controlled by the right side of the heart. After the blood has gone through the systemic loop, it returns to the heart through the superior vena cava and the inferior vena cava where veins enter the right atrium. The superior vena cava collects all the blood from the upper part of the body and inferior vena cava collects blood from the lower part of the body. Once in the right atrium, a contraction forces the oxygen-poor blood through the tricuspid valve into the right ventricle. When the right ventricle contracts, it forces the blood through the pulmonary semi-lunar valve and into the two pulmonary arteries which carry the blood to one of the two lungs. Once the oxygen has been “picked-up” and the carbon dioxide has been “dumped,” the blood flows back to the heart through the pulmonary veins where it enters the left atrium, thus started the process over.
The valves are needed because they prevent blood from flowing back into the chamber they came from. The muscle between the heart the splits it into a left and right side is known as the septum. The septum prevents oxygen-rich and oxygen poor blood from mixing.

"Wait, is that just fat?"

We have finally moved on from the muscular system and have now started the digestive system, a system that I find much more interesting! It is dissected easiest starting by the larynx, throat, and cutting your way towards the legs. While in the chest region, it is important to stay in the center because you will not be able to cut through the ribs with the scissors. Be careful not to cut any of the organs while cutting in the stomach region! Also, some of the ribs might get in the way and it will be helpful to actually cut the ribs so you can open the chest wider.
Once we had completed the cutting, Josh and I opened the cat’s body cavity and started pointing out different organs. However, what we thought was the small intestine was really the mesentery layer. Because our cat had packed on a few extra pounds, the mesentery layer had fat dispersed throughout causing it to look somewhat like the small intestines. Below is a picture of the difference.













After we removed the mesentery layer, we were able to see the small and large intestines. Another interesting thing we noted was how the kidneys are located under the intestines and are covered by a thick layer of connective tissue. The connective tissue connects the kidneys to the backside wall of the cat. Because of the thick connective tissue it was hard to see the kidney, and at first Josh and I thought it looked like our cat had a tumor. But no, it was just the cat’s kidneys.

What is Formaldehyde?

Today in lab, we continued with the muscular system and began cutting larger muscles in order to see the smaller ones beneath. The following link shows a man going through all the cat muscles, naming them and pointing them out. They are very helpful for studying!
Before we pulled our cats out of the fridge, Josh pulls out a bandana and ties it around his head, covering his nose and mouth. After laughing for a few minutes, I asked why he was wearing the bandana. He told me he had done some research and found out formaldehyde, the preservative in our cats, was not healthy for us to breathe in. Considering that we have a lady that looks about seven months pregnant, I decided to do a little research of my own.

First, I looked into the effects of formaldehyde on a healthy, non-pregnant person. Research has shown that formaldehyde is extremely harsh on the respiratory system and can promote asthma in children. Second, I looked at the affects of formaldehyde on pregnant women. Not only is formaldehyde bad for a pregnant woman, but also bad for any woman who plans on ever getting pregnant. Studies have been completed and “indicate that even a low level of formaldehyde may have an impact on fertility". Exposure to formaldehyde is associated with delayed conception and an increased risk of spontaneous abortion as well as stillbirth, pre-term birth, and congenital malformation. However, the study suggested that gloves did help in the prevention.
I think Josh will be the one laughing now as I will be buying some surgical masks.

Jinx's Loses a Few Pounds

In our first lab, our goal was to remove any excess fat, or adipose tissue, on our cat and locate a few key muscles. Before we get started there are a few key terms that you should know prior to dissecting a cat. First, the tools we use are scissors, which are a smaller version of normal scissors; a probe, which has a circular thin, metal piece to poke things; a knife, which is very dull; and tweezers, for the hard to reach areas. Also, connective tissue will be seen in almost every system of the body. Connective tissue is a thin layer of white to clear colored material that connects skin to muscles, muscles to muscles, muscles to organs, muscles to bones, organs to organs, and just about anything else that could be connected to something else. You will soon realize that connective tissue is hard to remove and is extremely annoying.
While removing fat might sound like a simple task, you should take a look at our over-fed, very voluptuous cat. Josh and I spent a good hour of the lab just removing fat from Jinx’s stomach. Removing the big chunks was pretty easy; however, the thin layer that covers our cat’s entire body was a little more difficult. In order to remove the thin layer of fat as well as the connective tissue without damaging the cat’s muscles, one must use the probe and rub back and forth with a great amount of pressure until the thin layer is no longer visible. It is important to use the probe because it will not cut the muscle.



When differentiating muscles, it is important to remember that all muscles are made up of individual muscle fibers. The fibers are small; however, you can see with the naked eye what direction the muscle fibers are running. For example, in the picture above you see the pectoralis major and the pectoralis minor and the only way to see the difference is by looking at where the muscle fibers change direction. It is very important that all the connective tissue is removed or else you will not be able to see the muscle differentiation. This link shows a good example of removal of the connective tissue. (scroll down to the bottom of the page to see the connective tissue)