On Thursday and Friday our Biology Class participated in a rat dissection. We had previously dissected a squid and an earthworm but neither were as exciting as the rat. We dissected a rat because it's body is closely related to a humans. Both a human and a rat are in the class Mammalia It was a surprising realization that the insides of a rat and human are similar but the physical appearances are so different.
The rat is part of the class Mammalia They have all the basic characteristics such as 4 chambered heart, fur, a diaphragm for breathing, amniotic egg, mammary glands for nursing, extensive post natal care and high learning and reasoning levels. Both the rat and humans are placental mammals. Both their tissues in the embryo and mothers uterus develop into a placenta which transfers nutrients and wastes between the mother and embryo. This allows the embryo to develop for longer inside the mother, unlike marsupials.
The rat dissection was a very hands on experience that I am glad that I got to participate in it. It was slightly nerve wracking because I felt like with one wrong cut the entire dissection could go wrong. However while moving along I became truly fascinated by the dissection and rat's anatomy. This was probably my favorite part of this course.
Discussion Questions:
1. Because you can easily feel the texture of the animal. It is also easier to grasp the animal. You can also be more accurate and precise with your incisions.
2. The different labels and titles for the dissection have the purpose of helping to keep the dissection organized. With these labels we can easily gain knowledge to what we are dissecting and having some what of a reference to look at.
3. A rat's tail is different from the rest of the body. It has a different texture. It looked scaly with fur. It also felt hard. The rat uses their tail for balance and to regulate their body temperature.
4. The purpose served by the vibrissae is tactile sensation. The vibrissae do not have any nerves in them.
5. My specimen is bilaterally symmetrical. This means that if an imaginary line was to be drawn down the middle of the animal, the two sides would be symmetrical.
1. The sphincter is a circular muscle. It is a ring of muscle that contracts to close an opening. For example the pyloric sphincter allows the stomach to digest proteins then opens up to allow the digested material to pass to the small intestine.
2. The small intestine is longer than the large intestine but it has a smaller width. In the small intestine the digestion and absorption of food occur. The large intestine helps to reabsorb the food and eliminate wastes.
3. The liver is the largest organ in the body. It has many functions such as, producing bile and proteins for blood plasma and proteins that help carry fat throughout the body. The liver also helps get rid of toxins and other poisonous substances. It converts ammonia into urea and produces immune factors and removes bacteria from the blood.
4. The duodenum acquired its name because it means 12 fingerbreadths (25 cm) in Latin.
5. The purpose of the appendix is in debate. Some scientists believe that it is a vestigial organ meaning that it has no use anymore. However studies are suggesting that the appendix hold bacteria which could be used to help cleanse out intestinal disease.
1. The function of the membrane is to help protect the cavities and make sure that the fluids don't escape the cavity. It also separates the layers as well.
2. The function of the spleen is to remove old red blood cells and also produce white blood cell lymphocytes.
3. The function of the diaphragm is to help with respiration and breathing. The contraction and expansion of the diaphragm helps inhale and exhale air from the lungs. The diaphragm is also used to expel vomit.
4. There are quite a few differences between the atria and ventricles. The atria are smaller than the ventricles. The atria is located above the ventricles and contains thinner tissues. The atria pump blood to the ventricles and the ventricles to the rest of the body.
5. The wall of the left ventricle is thicker than the wall of the right ventricle because the left ventricle pumps blood to the rest of the body.
6. A similarity between the male and female reproductive structures is the preputial glands. They are glands the secret hormones.
7. The kidneys clean and filter blood to remove wastes, stimulate the production of red blood cells, regulate blood pressure and substances in blood, and regulate the acidity of blood by controlling the amount of water in it.
8. The thyroid, the thymus and adernal glands belong to the endocrine system. This system regulates growth, mood and development. They also release hormones which influence every cell.
