Biology Essay Sample on Rat Dissection: Structure and Function

There are approximately 500 students per grade level, and each student attends seven classes per day.  There are about 100 classrooms in our school building with maybe fifteen of them being used for storage (give or take some).  The remaining eighty-five classrooms are then used to educate, instruct, and prepare students for the rest of their lives.  The structure of the school (grade levels, lockers, classrooms, etc.) allows for its system to work fluently and efficiently.  The school system works similarly to any multicellular organism, including rats.  The bodily function of a rat allows for it to thrive and take advantage of the ecosystem it lives in. Each and every part of the rat, internal and external, is structured in a way that influences its function. This helps it work towards creating homeostasis, or bodily equilibrium.  The structure of a rat greatly influences the function of its body.

The vast majority of mammals have tails.  Tails can be either long or short, depending on the animal.  Rats have long tails which are usually about the same length as a rat’s body.  They are rough, dense, and fairly flexible.  Their tails consist of a strong core layer of bone with over thirty vertebrae!  Six tendons connect these vertebrae to the muscles of the tail.  Many arteries and veins run in between the tendons.  Thanks to the thick outer skin, the tail of a rat has a thermoregulatory function;  this means that, in order to help regulate body temperature, it serves as a heat-loss organ.  Firstly, warm blood circulates to the surface of the tail.  Because the surface has less insulation, it is much cooler than the rest of the rat.  It loses heat the fastest.  This blood is then returned to the body at a lower temperature; this cools the rat down.  This helps the rat to maintain homeostasis.  In addition to keeping the body at a fair temperature, it also helps with balance.  Because the tail is long and fairly heavy, it counterbalances the weight of the rest of the body, allowing the rat to jump, climb, and run with ease.

All animals have a stomach.  The stomach is round and hollow, located just below the diaphragm on the upper left side of the abdomen.  It could be described as a pouch or container for storing food as it’s being broken down.  The shape is similar to that of a comma.  The stomach has gastric folds, or coiled sections of tissue, that exist within the layers of the stomach.  These coils allow for elasticity and expand when a bolus (a chewed up piece of food) enters the stomach.  The internal lining of the stomach walls contain cells that secrete a powerful, strong acid that assists in the breakdown process of the bolus. This happens because of the enzymes within the acid. Ridges of muscle tissue, called rugae, also line the stomach.  After passing through the esophagus, food is stored within the stomach for two hours or more.  The stomach muscles then contract periodically; this tosses, churns, and breaks down the food being stored. 

Every mammal has a pair of lungs.  They are located on either side of the thorax, or chest.  They are both spongy, and the shape and size of the lung are slightly different.  When a rat inhales, the oxygen travels through the trachea, or windpipe. Eventually, it reaches a section called the carina.  This is where the windpipe splits into two, with each side leading to either lung.  The air then travels throughout the lungs via its tubular branches, or bronchi.  These bronchi split and divide multiple times until they become microscopic bronchioles. The lungs contain alveoli, which are microscopic air sacs that allow for rapid gaseous exchange.   Alveoli, surrounded by capillaries, are where the lungs and blood exchange oxygen and carbon dioxide.  To breathe, the lungs need assistance from the intercostal muscles, abdominal muscles, and the diaphragm, which does most of the work.  Firstly, the lungs expand as air is sucked in.  Then, as the carbon dioxide waste is pushed out during exhalation, the lungs compress.  After passing through the lungs, the body then takes oxygen from the bloodstream and redirects it to other bodily tissues.  The blood gives up its oxygen in exchange for carbon dioxide extracted from tissues.  Then, it passes through the heart and to the lungs until it reaches the capillaries surrounding the alveoli.  By this time, the alveoli contain new oxygen that the rat has breathed in.  Now, when the rat exhales, it releases carbon dioxide.  Then the process repeats.  This is the process of gas exchange.

In conclusion, structure and function must work perfectly in unison in order for a rat to thrive. The body and interior parts of a car manage to maintain its shape when driving at high speeds; this is a popular analogy used to describe the way that the structure of a rat influences the function of its body.  Though attempting to understand the body can be very intimidating and overwhelming, it gets easier.  After putting in lots of time, patience, and effort, it is possible to understand how the structure of the body affects its function.