Fetal Pig Dissection
Also, to implement new skills such as dissection and the use of a scalpel as well as other related tools and to attain the ability to locate the organs of the mammalian system and compare their location to that of human organs. Through the process of sus scrofa dissection, insights have been made into the comparison of biological structures between mammals– particularly fetal pigs, and humans through study of the ventral cavity and the organs lying within.
The aforementioned dissection, which was performed with the use of specialized tools such as the scalpel, has yielded fruitful results leading to a greater understanding of the functions of organ systems in other life forms; including the fetal pig. Due to the four-legged nature of the fetal pig, there have been several similarities and differences regarding the human race and the fetal pig. Firstly, the pig possesses a tail whereas humans do not. The second differences observed were the large distinctions in facial structure.
The fetal pig, perhaps due to its linear body shape, possessed a thinner, more streamlined facial structure with large, upright ears, and an extended snout. Internally, the fetal pig and the human have been observed to have similar internal organ systems, with size as the major difference between the two. With this knowledge in mind, a better understanding of the differences and similarities between the biological structures of the human race and the animal kingdom has been attained for possible use in methods that could prove beneficial to both.
Due to the great similarity between the functions of human organ systems, and animal organ systems, future developments in animal organ transplants are in sight, for the greater benefit of mankind. Submitted To: Mrs. Pellegrino Submitted By: Johans Mascardo Lab Partner(s): Derrick Porter Date Performed: Monday, April 3, 2011 Date Due: Friday, April 8, 2011 Course Code: SBI3U1-07 Mammalian and Human Organ System Differentiation During Fetal Pig Dissection Introduction This report represents a study of the organ systems contained mostly within the ventral body cavity of a fetal pig through the method of dissection.
Dissection provides valuable information pertaining to the importance and the primary functions of mammalian organ systems—particularly the circulatory, respiratory, and digestive systems—in relation to humans. This lab provides a new, direct, and unique approach to studying the path of food towards digestion, the flow of blood through circulation, and the exchange of air during respiration. Also, due to the mammalian nature of the organs being studied, comparisons can be drawn to the organs of humans, whose own systems appear to be very similar both in shape and function.
Locations of these organs are studied closely to provide insight on how they contribute to the effectiveness and efficiency of the system as a whole and to answer the question of whether or not this applies to humans as well. Purpose: 1. To Compare and Contrast the functions of organ systems of humans and fetal pigs, primarily those contained within the ventral body cavity, which includes both thoracic and abdominal cavities. 2. Implement new skills such as dissection and the use of a scalpel as well as other related tools. 3.
To locate the organs of the mammalian system and compare their location to that of human organs. Questions: 1. Are fetal pig and human internal systems different? 2. What skills were gained in the process of this lab? 3. What is the difference in location of the organs of the mammalian system in comparison to humans? Hypothesis: The performing of dissection would implement new skills to be learned and honed for future use such as the proper handling of the scalpel, and the use of the dissecting tray, pins, and related apparatus.
Through the use of dissection, it will be shown that the mammalian organ system is indeed similar to the of homo sapiens, both in appearance and function. The sizes of the organs may differ, which lends to the fact that animals such as pigs have very different diets to those of humans. If the muscles surrounding organs such as the stomach and the digestive tract are stronger or larger, it may due to a greater need for efficient contraction and peristalsis when swallowing which would suggest that the animal’s diet consists of larger, harder foods which would require a degree of strength to swallow and digest.
However, if the muscles are found to be smaller in organ size to muscle ratio than those of humanoids, it would reveal that the pig’s diet is lighter than those of humans, resulting in less dedication to muscle development in that area. Also, because the pig is an animal the does not stand upon its hind legs and spends much of its lifetime on four limbs, it would result in various changes to the pig’s circulatory system. Because of the fact that the pig’s natural position is horizontal, contractions in the valves of arteries are weaker due to the less required pressure needed to propel the blood vertically if the animal were standing.
Materials: – Fetal Pig – Gloves – String – Garbage Bag – Press and Seal Apparatus: – Forceps – Dissecting Probe – Dissecting Scissors – Scalpel – Blades – Dissecting Pins – Small Beakers – Eye Dropper – Goggles – Dissecting Mat – Procedural Diagram Book – Measuring Tape Procedure: Part 1: External Anatomy 1. Fetal pig was placed on the dissecting tray. Its length is measured and the age is recorded with use of a statistical graph. 2. The regions of the pig’s body were identified and noted (Ritter, & Adam-Carr, pg. 308). 3.
The pig was placed on its back and various features are identified, such as the umbilical cord and paired rows of nipples appearing on the pig’s ventral surface. 4. The feet were examined and the position and number of the toes are noted. Part 2: Abdominal Cavity 5. While the pig was on its dorsal surface, a piece of string was attached to a hind leg and pulled beneath the dissecting pan before being tied to the other hind leg. The same procedure was done for the fore legs. 6. The first incision was made with scissors/scalpel**.
The incision was first made around the umbilical cord before cutting towards the anterior of the pig. 7. The second incision was made towards the posterior of the fetal pig, followed by the third incision which was made at the end of incision #1 arcing towards both of the pig’s shoulders. The fourth incision was made at the end of the second, arcing towards and across the pig’s inner thigh. The fifth incision was made horizontally, parallel to the diaphragm, in order to separate the thoracic and abdominal cavities of the pig (Ritter, & Adam-Carr, pg. 309). 8.
Flaps along incision #5 were pulled off to reveal the abdominal cavity and the probe was used to open the connective tissue that holds the internal organs to the lining of the body cavity. Flaps covering incision #4 were also pulled apart and revealed the posterior portion of the abdominal cavity. The flaps of skin were held back with the use of pins. 9. The liver was located along with the number of lobes. 10. The lobes were then lifted with the probes in order to locate the gall bladder. 11. The small intestine was then located by following the bile duct. 12.
Beneath the liver, the stomach was located and with the forceps and probe, lifted in order to locate the esophagus near its anterior end. 13. With the probe and forceps, the junction between the stomach and small intestine was lifted and the supporting tissue was then removed. The junction was then uncoiled and the creamy white pancreas was located. 14. The spleen was located around the ourter curvature of the stomach. 15. The scalpel was then used to remove the stomach through the use of transverse cuts near the junction of the stomach and the esophagus, and near the junction of the stomach and the small intestine.
A cut along the midline of the stomach was then made in order to open the cavity. It was then rinsed and viewed under a hand lens (Ritter, & Adam-Carr, pg. 310). Part 3: Thoracic Cavity 16. The flaps of skin covering the thoracic cavity were then folded back and attached to the dissecting tray with the help of dissecting pins. 17. The heart was located within the thoracic cavity and the pericardium was removed with the use of the forceps and a probe (Ritter, & Adam-Carr, pg. 311). 18. Blood flow from the head and upper body to the right side of the heart was examined through study of the superior and inferior vena cava. 9. Blood flow through the heart was then traced, beginning with blood collecting in the right atrium and ending with blood being pumped out of the aorta. 20. A diagonal incision was made across the heart to expose the heart chambers. The thickness of the ventricle wall is compared to that of the atrium. 21. The lungs were then located and the trachea was found. 22. Trachea was then pushed down with the index finger and water flowed through a hole which had resulted from an earlier puncture. The lungs expanded slightly (Ritter, & Adam-Carr, pg. 312). Observations Fetal Pig age/size ratio:
The fetal pig dissected was 450mm long from the tip of the snout to the end of the tail. This equated to an estimated age of 150 days. What is the position of the pig’s toes and the number of them? The pig possessed four toes with two on the bottom half of the foot and two on the upper half, allowing for greater stability when standing upright on all four legs. How many lobes are in the liver? The liver of the fetal pig contained five lobes in total. Describe the location of the gall bladder: The gall bladder was located behind the liver, pushing up against its under surface.
It was located above the intestines and on the right side of the fetal pig’s rib cage. Describe the appearance of the pancreas: The pancreas was a creamy white colour with shades of pink and appeared to be bean shaped with several wrinkles or folds of tissue. It was located beneath the stomach and above the large intestine. Inner Lining of the Stomach: The folds of tissue in the stomach were seen, which were later identified as the rugae, which increase surface area for food. Portions of partially digested meals were also found inside the stomach. List the organs found in the thoracic cavity: * The Heart * The Lungs * Trachea * Larynx Bronchi Trace blood flow through the heart: Deoxygenated blood enters the heart via the superior and inferior vena cava into the right atrium. It then passes through the atrioventricular (AV) tricuspid valve to the right ventricle, where it is pumped through the pulmonary semilunar valve, out from the pulmonary artery and to the lungs, where it gets oxygenated. Once oxygenated, the blood returns to the heart via the pulmonary vein into the left atrium, where it passes through the AV bicuspid valve into the left ventricle where it is pumped through the aortic semilunar valve out of the aorta towards the carotid and subclavical arteries.
Describe what happens when you push down on the trachea: When the trachea was pushed down, air filled the lungs, which caused them to expand slightly. However, due to a puncture on the base of the trachea, water seeps out of the whole and air does not completely enter the lungs. The respiratory system of a fetal pig An open fetal pig, revealing the abdominal and thoracic cavities and the organs within (“Fetal Pig Dissection,” 2010) \ The heart of the pig and arteries associated with it. (Uzwiak, 2010) Analysis Questions a) What is the function of the umbilical cord?
The function of the umbilical cord is to transport deoxygenated blood from the fetus and return oxygenated blood to the fetus. It also aids in delivering nutrients to the fetus and removing wastes (“General about the,” 2010). b) State the function of the following organs: stomach, liver, small intestine, gall bladder, pancreas, large intestine, and spleen. Stomach: The function of the stomach is to break down and digest food, turning it into chyme. The stomach prepares food for absorption by the small intestines and breaks it down with the use of enzymes such as trypsin or pepsinogen (Ritter, & Adam-Carr, pg. 214).
Liver: Produce enzymes that break down fats, converts glucose to glycogen. It helps in the creation of amino acids and can filter harmful chemicals or substances from the blood, such as alcohol. The liver also aids in maintaining homeostasis regarding the level of glucose in the blood (“The human liver,” 2010). Small Intestine: The main function of the small intestine is to finish of digestion, absorb nutrients which have taken on the form of chyme, and neutralize the acids from the stomach (Ritter, & Adam-Carr, 2002). Gall Bladder: Stores bile, which is released when food containing fat enters the digesting tract.
This stimlates the secretion of cholecystokinin (CCK). The bile emulsifies fats and neutralizes acids (Ritter, & Adam-Carr, 2002). Pancreas: The pancreas secretes hormones such as glucagon and insulin, which aid in homeostasis of blood sugar levels. It releases glucagon when sugar levels are low, and insulin when they are high. The pancreas also possesses the task of producing chemicals which neutralize acids that pass from the stomach to the small intestine. The pancreas completes digestion of proteins, fats, and carbohydrates (“Pancreas: function,” 2011).
Large Intestine: The large intestine’s job is to reabsorb water and maintain the balance of fluids in the body as well as processing undigested materials such as fiber, absorbing vitamins, and storing waste before it is eliminated. Fiber helps in stimulating bowel movement as it adds waste to the feces before it is expelled (“The digestive system,” 2006). Spleen: The spleen’s functions are to create lymphocytes which destroy and recycle old erythrocytes. It also acts as a blood reservoir to help counter low blood pressure or aid in clotting among other things (“Human spleen,” 2006). ) What is the function of the mesentery? The mesentery supports the intestines, keeping them in place and allows for changes in size and position (“Human intestine,” 2011). d) Why does the left ventricle contain more muscles than the right ventricle? The left ventricle contains more muscles than the right ventricle because it has to pump blood out to the entire body, whereas the right ventricle pumps blood only to the lungs, which is located in close proximity to the heart (Ritter, & Adam-Carr, pg. 256). e) Why do the lungs feel spongy? The lungs feel spongy because of the millions of alveoli nestled within them.
These alveoli are tiny air sacs which have pores that allow for the diffusion of oxygen. Because of these pores, the lungs resemble the makeup of an actual sponge, because when it expands, air enters, and when it is compressed, air escapes (“The internet encyclopedia,” 2011). f) What function do the cartilaginous rings of the trachea serve? The cartilaginous rings of the trachea serve the purpose of keeping the trachea, or airway, open. If the trachea were to close, air would be unable to enter or escape, cutting off all gas diffusion. No oxygen means no ATP and this would ultimately result in cell death (Ritter, & Adam-Carr, pg. 86). g) Make labelled diagrams of the following: Refer to observations h) Write a report in which you point out the similarities and differences between the anatomy of the pig and of the human. Due to the four-legged nature of the fetal pig, there have been several similarities and differences regarding the human race and the fetal pig. Firstly, the pig possesses a tail whereas humans do not. The second differences observed were the large distinctions in facial structure. The fetal pig, perhaps due to its linear body shape, possessed a thinner, more streamlined facial structure with large, upright ears, and an extended snout.
Other differences were also examined, such as the number and positioning of the toes. Pigs have four toes pointing downwards, which may help in balance as it walks. Internally, the fetal pig and the human have been observed to have similar internal organ systems, with size as the major difference between the two. The positioning of the intestines between the two are remarkably similar, and the thoracic and abdominal cavities are nearly the same. Fetal pigs do have differences regarding muscle size. Due to their equal usage of their legs, the fetal pig examined, like many other four-legged animals, was shown o have similarly dense muscles and thighs, a trait unmistakeably passed down through generations of pigs and centuries of treading four legged upon the earth. i) You have just dissected a fetal pig, but there are other methods of learning internal systems. i. e. Computer simulation software / virtual lab. State some of the adv/disadv in doing fetal dissection. State some of the adv / disadv of doing virtual dissection. In fetal dissections, it is possible to gleam firsthand experience of the workings of the body, human or not.
Invaluable experience is gained through fetal dissection and skill with the scalpel and other dissection tools are honed for use in future careers. If a student wishes to find employment in the medical field, surgical experience–if only gained through dissection, is a helpful asset. However, as with many things, dissection has its downsides. Firstly, during dissection, it is imperative that the dissecting student take care in the position and depth of their cuts so as not to do damage to the organs and tissues underlying the location being cut. Errors are irreversible.
For example, piercing the pancreas or the stomach would remove the opportunity to examine the aforementioned organs in their original state. Lastly, fetal dissection requires the use of consumable items, so multiple uses would not be a viable option, and there aren’t any ‘resets’ or redo’s. In virtual dissections, there is the advantage of reversing these mistakes and redoing the procedure as many times as needed. There is also an infinite amount of time available for the procedure, as the materials do not become unusable, and the pig does not waste away.
However, with virtual dissection comes several disadvantages, including the inability to examine the specimen from various angles or distances. There is little free roam or freedom to explore. Also, you lose the valuable knowledge that was to be gained with fetal dissection such as the uses of a scalpel and scissors as well as the knowledge of the careful procedures involved with removal of the organs. j) After the dissection, the fetal specimens and liquids need to be disposed of safely. This can be an environmental hazard since fetal pigs are bathed in fixative residue.
Investigate what precautions are used in the fetal pig. How might this harm you or the environment if not disposed of properly? Fetal pigs are preserved by being bathed in formaldehyde, which is a harmful substance that is used in the production of fertilizer, paper and plywood, as well as a preservative in some foods, antiseptics, medicines, and cosmetics. Formaldehyde at room temperature is a colorless, flammable gas with a pungent smell. It is a harmful substance that can damage the dermal, gastrointestinal, immune, and respiratory systems.
When disposing, it is critical that the neither the liquid nor the pig escape the bag or bin, as the smell could cause various illnesses, particularly cancer because formaldehyde is a carcinogen. Formaldehyde’s effect on the environment and to plants are reduced due to degradation. It is removed from the atmosphere with free radicals (“Formaldehyde,” 2011). k) Research how the fetal pig is prepared (killed) Fetal pigs are not killed, but taken from pregnant sows at the slaughterhouse. They are a by product of the meat industry.
Before they are slaughtered, fetuses are removed from the sow and sold for educational purposes such as dissection (“Questions and answers about dissection,” 2011). Conclusion The purpose of the fetal dissection was to compare and contrast the functions of organ systems of humans and fetal pigs, primarily those contained within the ventral body cavity, which includes both thoracic and abdominal cavities. Also, to implement new skills such as dissection and the use of a scalpel as well as other related tools and to attain the ability to locate the organs of the mammalian system and compare their location to that of human organs.
During the process of the lab, various errors were made, including the puncturing of the central lobe of the liver. The scalpel penetrated deep and the stab wound was clean and straight due to the nature of the liver tissue, which is dense and not as tightly wound as other tissues of the body. Another error made was the puncturing of the pancreas, which was a result of a uncoordinated cut to remove the intestine from the abdominal cavity of the fetal pig. The remaining pancreatic tissue was observed to be somewhat bean shaped with wrinkle or folds, displaying a pinkish creamy hue.
Fetal pig dissection is a useful and invaluable method of learning which enhances students’ abilities to operation in a surgical-like environment. The experience gained is a useful asset for prospective students in careers dealing with the human body and surgery. The hypothesis made was correct in that the internal systems of mammals and humans are indeed the same, differing only in size. The functions and appearances are the same. Many of the differences between fetal pigs and humans are found externally, such as the presence of a tail, four toes on each foot, a long snout, and upright ears.
Fetal Pig dissection labs are extremely useful for students as they provide a frontier for students to test their skills or gain new ones a have interest piqued towards a career in medicine. With a greater influx of interest towards medicine, advances would be made much quicker and many of humankind’s existing problems could be treated, including but not limited to cancers, viruses, and organ failures especially. Through dissection of the fetal pig, it was found that the internal organs of pigs are much like human’s including function and shape.