Rat Dissection Lab Report

The objectives of this lab were fulfilled. During the dissection, diagrams of the rat were conducted from several different perspectives including both the dorsal and ventral views. Throughout the dissection, the prior knowledge that was theoretically learned in class, assisted in allowing the group to have a more complete and thorough understanding of the different organs, and parts that were present in the rat. This helped reveal the several different similarities and differences in the circulatory, digestive, and respiratory system when comparing the rat and human.

Both similarities and differences between the rat and the human were evident while participating in the dissection. As mentioned before in the introduction, both rats and

humans are omnivores which imply that they share a similar digestive system.

While conducting the dissection, only four teeth were observed in the specimen, which consisted of the two incisors on the top, and two on the bottom. However, subsequent to the dissection it was noted that rats possess 16 teeth consisting of both incisors and molars (website 3, 2004). Humans possess 32 teeth that consist of 12 molars, of which four are wisdom teeth. Nowadays, several people are getting their wisdom teeth removed, which is somewhat due to the fact that they have become “useless” throughout the years. Modern diets consist of softer foods, which have eliminated the purpose of wisdom teeth that were once distinct (website 4, 2007). However, due to the rat’s diet consisting of “rough” foods, all 12 of its molars are useful in providing more “chewing power”, and force. Another difference that was between the rat and the human that was observed in the dissection was the size of the caecum (see figure1). One of the main purposes of the caecum is to digest cellulose. Rats

consume a variety of food, including many plant materials which contribute to the size of its caecum. However, since the majority of humans consume much more meat and fatty nutrients than plant materials, the size of the caecum is much smaller. One unexpected result that came from observing the digestive system was the absence of a gall bladder in the rat. The purpose of the gall bladder is to store and concentrate bile which is essential in breaking down fats during chemical digestion. The gall bladder has a distinct role in our digestive system, so the observation that it was absent in the rat
When comparing the respiratory system of both the rat and the human, there are little to no differences (refer to figure 2). Both the rat and the human share similar oxygen flow/passage. For example, in both animals oxygen enters the nasal passage, pharynx, trachea, bronchi, bronchioles, and then the alveoli which allow the oxygen to move between the lungs and the bloodstream (website 5, 2003). Furthermore, both the lungs of the human and the rat help provide the same purpose of getting the oxygen to each cell in the body, in addition to removing carbon dioxide from the body.
In addition to comparing the respiratory system, and digestive system of both the rat and the human, observations of the circulatory system were also made. While conducting the dissection, it was at first thought that the heart of the rat was not similar to humans because of the significant contrast in size. However, after observing the heart much more closely through cutting inside, it was concluded that both the heart of the rat and human were very similar, and consist of four chambers. Additionally when comparing the size the rats paw, to its heart, it was basically the same. This fact is also true when comparing the size of a human’s closed fist to its heart.