Similarities and Differences between Fetal Pig and Sheep Heart

1.a. I did not notice much differences between the two hearts. However, the difference between the fetal pig heart along with the sheep heart is that the heart of the fetal pig is smaller than that of the sheep heart. On the other hand, the similarities are that both the specimens possesses the same anatomy. Accordingly, both have right and left atriums similar to right and left ventricles. The third similarity is that both have prominent great vessels just like the pulmonary artery along with the aorta (Rizzo, 2015).

b. The 4 valves of the heart in the fetal pig are the tricuspid valve, pulmonic valve, mitral and aortic valve. The tricuspid valve is located between the right atria and the right ventricle. As an illustration, the right atrium usually gets deoxygenated blood which returns from circulation within the body via superior Vena cava which is then pushed via the tricuspid valve into the right ventricle (Allen & Harper, 2014). The deoxygenated blood is then forced from the right ventricle through the pulmonic valve to the lungs to get oxygen.

The pulmonic valve is termed as the semilunar cusped valve which is found within the ostium of the pulmonary artery.  Blood usually moves to the heart from the lungs via the pulmonary vein into the left atrium. From there, blood then moves through the mitral valve into the left ventricle. The mitral valve is usually a bicuspid or leaflet atrioventricular valve. The left ventricle usually contracts when it gets full, and hence blood is pushed into the aortic valve via aorta into the body (Rizzo, 2015). The aortic valve are found along the root of the aorta at its junction with left ventricle. It is usually a high pressure, cusped semi lunar valve which must withstand tremendous pressures during the election from left.

c. The heart is usually masculine on the left ventricle together with the left atrium. Conversely, the difference is their sizes. In this case, the left side of the heart was larger than the right side. Furthermore, the right and left ventricles had papillary muscles along with chordae tendinea which attaches the tricuspid and mitral valves to the interventricular wall. Accordingly, the right side circulates blood without oxygen while the left side circulates oxygenated blood. Last but not least, the aortic and tricuspid valve was at the left side of the heart while the tricuspid along with pulmonary valve was on the right side (Reece & Rowe, 2017).

Left and Right Sides of the Heart

d. The mitral along with tricuspid valve are both atrioventricular valves. However, the mitral valve possesses two cusps while the other valves have three (Allen & Harper, 2014). The valves are anchored to the walls of the ventricle with the chordae tendineae which is absent in semi-lunar valves. Furthermore, they are responsible for the first sound of the heart called LUB sound (Denbow, 2015).

The aortic and pulmonary valves termed as the semi-lunar valves. Conversely, they usually work more like the valves in veins to avoid backflow of blood. Accordingly, the semi-lunar valves are typically responsible for the second sound of the heartbeat which is called the DUB sound (Roper & Voss, 2014).

e. The Papillary muscles are small muscles within the heart which attaches to the chordae tendineae. However, this tendinea are usually attached to the mitral valve along with tricuspid valve thus preventing the backflow of blood from the left ventricle into the atrium. They looked like tough strings within the sheep heart specimen (Rizzo, 2015).

f. From the right atrium, the blood usually flows via the tricuspid valve into the right ventricle. From the left ventricle through the pulmonic valve into the pulmonary artery towards the lungs. The deoxygenated blood in the lungs is usually passed through tiny structures referred to as alveoli where there is an exchange of oxygen and carbon dioxide via the capillary walls (Denbow, 2015). When the blood gets full of oxygen, it moves back to the heart through the left atrium. From there it passes via the mitral valve and into the left ventricle. The left ventricle usually pushes the blood past the aortic valve into the aorta and hence out of the body to supply blood rich in oxygen throughout the body. The blood from the whole parts of the body usually returns to the heart via veins. That is the superior vena cava and then into the right atrium to start the oxygenation process again (Allen & Harper, 2014).

2.a. Trachea and esophagus are usually part of the respiratory and digestive system respectively. However, since they belong to different systems they perform different functions. As an illustration, the trachea is generally surrounded by a ring-shaped cartilage that is hard to keep it open all the time to facilitate gas exchange. On the other hand, the esophagus is usually flexible to allow the foods and liquid movement. Accordingly, the trachea is defined by two parts that are the thoracic and the cervical (Roper & Voss, 2014). The esophagus possesses three parts that is the thoracic, cervical and abdominal and hence extends from the lower side of the pharynx to the cardiac opening of the stomach. The esophagus also has some constrictions at the places it originates, and therefore food can lodge themselves within these areas (Allen & Harper, 2014). The trachea usually has two parts while the esophagus has three parts.

Atrioventricular Valves and Semilunar Valves Structure Comparison

b. Structures of the trachea, bronchi, and lungs were all within the fetal pig. The trachea is rigid and hollow tube-like which when felt had several small hard rings surrounding it. This was the cartilages which surround the trachea to keep it upright and patent for the gaseous exchange (Scanlon & Sanders, 2014). The two Bronchi which are usually interlinked by the trachea could be described as upside-down tree as they spread further into bronchioles in the lungs (Rizzo, 2015). In fetal pig, the left lung had three lobes while the right lung had four lobes. Accordingly, the lungs of the fetal pig were dark pink to almost red and had a spongy texture because of millions of alveoli which make up the surface area of the lungs (Denbow, 2015).

c. I could describe the texture of the lungs as spongy. Accordingly, both the left and right lungs were relatively light.

d. The lungs in the right side were shorter and broader while the left lung is long and narrow. However, both of them usually facilitates gaseous exchange through millions of the alveoli in each (Denbow, 2015).

3.a. The structures of the kidneys of both the pig and sheep resembled each other. However, the notable difference was their sizes. The kidneys in both specimens had common bean shaped shape which appeared dense to touch (Roper & Voss, 2014). The Kidneys of the pig were however located below the small and large intestine and were covered in a shining coating which is called peritoneum which had to be dissected away from the kidney before it could be accessed. Furthermore, both the kidneys had a visible renal artery, renal vein along with the ureter which was attached.

b. The kidney was found in the abdominal cavity dorsal under the lining of the peritoneum (Scanlon & Sanders, 2014).

c. Urine usually starts from the kidney. It is the kidney that filters the blood wastes which comes in form of urine. Urine however is termed as the mixture of water, urea, salts, ammonia, and creatinine. When blood goes through the renal capillaries, it is then taken into structures called the glomeruli which are just like a filter (Rizzo, 2015). However, its structure usually allows the waste products, water, and salt to pass from the blood into a tiny channel called tubule while keeping the blood cells along with protein in the bloodstream. There are over a million nephrons in each kidney. Urine usually travels from the tubules through the ureters attached to each kidney down to the bladder where the urine is stored until excretion. The body gets ride of urine via the Urethra (Roper & Voss, 2014).

Papillary Muscles Appearance

4.a. The thyroid and thymus glands are the organs which are found within the throat. The thyroid gland found above the trachea in fetal pig was oval with a dark red appearance. The function of the thyroid gland is usually to maintain basic metabolic rate along with production of thyroxin. On the other hand, the thymus gland in the pig is located above the heart. The thymus gland was whitish and had two lobes (Scanlon & Sanders, 2014).

b. The Endocrine gland organs within the abdominal cavity are pancreas, adrenal glands together with the testicles. The pancreas was small and had the texture of small pebbles. However, it was located behind the stomach. The pancreas had a grey to whitish color (Scanlon & Sanders, 2014).

The adrenal glands in pig were tiny and were located anterior to the kidney. Furthermore, they had an oval shape and were very light. Last but not least, testicles were situated on the fetal pig. They were near the anus and surrounded by the sac called scrotum.

5. a.The stomach, esophagus, small intestine along with large intestine are the major digestive organs of the fetal pig. The function of the stomach is usually to store around one to two litres of food for digestion. Furthermore, the stomach lining produces rennin which coagulates milk proteins. I saw the esophagus at the back of the pig’s trachea which was very small and flexible tube whitish in color. It usually links the stomach and hence was found in the abdominal cavity to the right slightly under the liver. Accordingly, I dissected the pyloric sphincter which was found underneath the stomach and leads to the small intestine. This usually prevents backflow of food and has thicker layers (Reece & Rowe, 2017).

The small intestine appeared to possess many loops than large intestine, pink to whitish and very smooth from outside. The inside of the small intestine had projections. This is where the absorption of nutrients usually takes place. On the other hand, the large intestine was darker in color. It was around one meter long and around 10cm wide. Its main function is to absorb water, minerals and salt. Accordingly, the large intestine had few loops as compared to those in the small intestine and had a rigid appearance. I then moved to the anus where the fecal matter moves out of the body (Roper & Voss, 2014).

b. I would describe the accessory organs of the digestive system as Teeth, tongue, salivary glands, pancreas, liver along with the gallbladder. However, every organ usually plays a function within the digestive system. The tongue was not easily accessible since the jaws were tightly closed. However, the tongue is used in digestion to push food towards the back of the throat (Scanlon & Sanders, 2014).

During dissection I saw three salivary glands in the fetal pig which includes the parotid gland, the mandibular gland along with the sublingual gland. The pancreas gland in pig was small and grey to white located just under the liver. Pancreas usually produces insulin. The liver was large and dark in color. The liver had a very dense texture and took the significant portion of the abdominal cavity (Reece & Rowe, 2017). The function of the liver is usually to process the nutrients absorbed from the small intestine along with secretion of bile into the small intestine for fat digestion. Lastly, the gallbladder was under the liver. It is a small sac which appeared dark green. The gallbladder usually holds bile which is produced in the liver.

References

Allen, C., & Harper, V. (2014). Fetal pig dissection: a laboratory guide (No. Ed. 3). John Wiley & Sons Ltd.

Denbow, D. M. (2015). Gastrointestinal anatomy and physiology. In Sturkie’s Avian Physiology (Sixth Edition) (pp. 337-366).

Reece, W. O., & Rowe, E. W. (2017). Functional anatomy and physiology of domestic animals. John Wiley & Sons.

Rizzo, D. C. (2015). Fundamentals of anatomy and physiology. Cengage Learning.

Roper, C. F., & Voss, G. L. (2014). Guidelines for taxonomic descriptions of cephalopod species.

Scanlon, V. C., & Sanders, T. (2014). Essentials of anatomy and physiology. FA Davis.