Rat Dissection

For our biology classes final dissection of the year, we were to dissect a rat. This dissection was much bigger than what we've previously done, beating the earthworm and the squid by a long shot. We were given the usual tools for the dissection, a scalpel, pins, and tweezers, yet our group was still divided on who should be the one to cut the rat open. By that i meant that no one wanted to do it, leaving it to me to start the dissection.We analyzed the external anatomy first, finding the rat's various body parts and openings, including the urethra, anus, and mouth. It was now time to cut our rat open. we made our first incision along the length of the rats stomach, and splitting the lines along it's hind legs and fore legs. Upon opening it's body, we found the rat's digestive cavity, and it's rib cage  which we cracked open at a later time to get at the heart and lungs. We were able to identify the small and large intestines on sight, and the stomach and other processing organs, like the liver and kidneys after some digging around. The thing that surprised me about the worm was how similar it was compared to our anatomy. It would have to do with the phylum that we are grouped in, as well as our class of mammalia. The dissection was a truly interesting experience, even more so since they belong in the same phylum, sharing similar organs and body functions that we do, even with some differences due to the differences of our orders. The rat dissection was a fun experience and i hope to see what things that'll be done next year in biology!

1. Why are your hands the best tools for dissection?
Our hands are the best tools for dissection as they are very versatile, much more so than most other tools, and we can control them much better considering they are our own appendages. They also help us feel what we are dissecting, allowing us to understand the purpose of the dissection more so than with a cold tool.

2. What is the purpose of having all the different titles and labels for the dissection?
They provide accurate information towards the assignment at hand, and allow us to focus in specific parts of the body, instead of aimlessly wandering around the inside of the body.

 3. In what way does the tail differ from the body?
The rat's tail is much more stiffer and coarse, as well as appearing to have scales along the length of the tail.

4. What purpose is served by the vibrissae?
The vibrissae allow the rat to detect disturbances or changes in its environment.

5. Your specimen is bilaterally symmetrical, what does that mean?
This means that the rat has a line of symmetry, meaning that one side of the rat would be the same as the other side of the rat, laterally speaking. This also means that this species is highly developed, as all developed phyla exhibit bilateral symmetry.

6. The sphincter is described as a circular muscle. Why is it this shape and what does it do?
The sphincter is an opening that regulates the flow of substances, such as urine or blood. They are circular to fit into the shape of the tubes that they belong in, which are also circular in shape.

7. Why is there a difference in size between the small and large intestine?
The intestines differ in size as the large intestine is made to process and create the waste, while the smaller intestine is smaller to increase nutrient absorption as it passes from the stomach.

8. The liver is the largest organ in the body, what purpose does it serve?
The liver is a processing organ, like the kidneys. They detoxify the things taken into the body and create chemicals to aid in digestion.

9. How did the duodenum acquire it's name?
The duodenum is names after 12 finger widths (around 20 centimeters) and has a Latin origin.

10. What purpose does the appendix  provide in animals that still retain it as a functioning organ?
The appendix is used to breakdown cellulose, mainly found in the diets of herbivorous mammals. The organ contains bacteria which assist in the breakdown of cellulose.

11. In each cavity, there is a membrane that covers both the wall of the cavity and the organ it 
contains. What is the function of the membrane?
The function of this membrane, like all the other membranes of the body, is to protect and contain the organs and parts of the body to prevent damage, like for example the organs mixing up with another, changing places with where they are supposed to be.

12. What is the function of the spleen?
The spleen works as part of the immune system and produces/stores blood cells for the circulatory system.

13. What is the function of the diaphragm?
The diaphragm controls the flow of air into the lungs, pulling the lungs upwards and downwards to expand
the chest cavity to let air in.

14. What distinguishes the atria from the ventricles?
The atria hold the blood as it enters the heart, keeping it until it is then passed onto the ventricles, which push he blood to where it needs to be.

15. Why is the wall of the left ventricle thicker than the right?
The left ventricle is responsible for pumping oxygenated blood to the entire body. This means that the thicker wall is meant to give it more power to push the blood as far as it needs to go, unlike the right ventricle, which only needs to take blood to the lungs.

16. What similarities exist between the male and female reproduction system?
The male and female reproductive systems are both completely different, aside from the adrenal glands and the connection to the bladder. They also share the pituitary gland.

17. What do the kidneys do?
The kidneys are responsible for processing the blood, getting rid of as much waste as possible. It collects the waste from the blood and sends it to be excreted in the form of urine.

18. What system of the body do the thymus, thyroid, and adrenal gland belong to?
The thyroid, thymus, and adrenal glands all belong to the Endocrine system, or the system responsible for the control and releasing of hormones involving the metabolic function of the body.

THYMUS- Produces T-cells for the immune system

THYROID- The largest endocrine organ, and controls how sensitive the body is to other hormones, makes protein, and controls how quickly the body uses energy

ADRENAL GLAND-Releases hormones in response to stress and affect kidney function.