Big+Mac

=** General Anatomy **= Meet Big Mac. Whattabro. This is Big Mac, who was named after a famous type of McD's burger in spite of the fact that pigs are not generally used for burgers. We've pointed out some defining characteristics that are unique to mammals: hair and nipples. Another feature only found in mammals is the presence of nails, which we will discuss later.

Here is a perspective of Big Mac's mouth. We can clearly see a row of teeth; the jaggedness of the lower incisors suggests a diet composed of tough materials, such as roots or even meat. A ring of inflamed taste buds are present in spite of the fact that this is the underside of the tongue. (The fact that a little portion of Big Mac's tongue was hanging out of her mouth and thus was exposed to many preservative chemicals most likely caused this irritation.) Big Mac's taste buds are much more prevalent on the obverse side of the tongue.

The rest of Big Mac's taste buds, most of which are not inflamed, are clearly visible here. We can also see more of Big Mac's teeth, which are much more prominent and sharp here. In addition, we can easily discern the hard palate, but the soft palate, which continues down into the mouth after the hard palate, is slightly hidden as a result of the tongue's shadow.

Here we can clearly see each of Big Mac's toes. Pigs use digitigrade locomotion, which essentially means they walk or stand on their toes. On the other hand, we humans use plantigrade locomotion, which means we walk or stand with our feet flat on the ground. Also pictured above are the nails, a defining feature of mammals.

The Genital papilla can be seen just ventral of the anus. The urogenital opening is on the genital papilla, however it is not visible in this picture.

A good cross section of the umbilical cord is pictured above. The umbilical arteries are highlighted with coagulated blood, while the vein lacks any substance within. The umbilical arteries carry oxygenated blood out of the fetus and the vein carried deoxygenated blood, rich with carbon dioxide, back to the fetus.

Pictured above is Big Mac's folded urinary bladder.

Here we can see many of the larger organs involved in the digestive system as well as the diaphragm, which stretches all the way across the body cavity.

Displayed above is a better view of the diaphragm, which is a key component in respiration. Although Big Mac never had a chance to breath, she still needed a fully developed diaphragm for her first breath. It sits between the thoracic and the abdominal cavity, separating and sealing the two off from one another. When at rest, this large muscle lies in a concave position, arching up into the superior cavity. Upon contraction, it flattens out, thus forcing the lungs above to expand into the space created. The result is inhalation. When the diaphragm relaxes, it and the lungs return to their original respective positions. Although muscles found in the ribcage also assist in breathing, the diaphragm is perhaps the most essential muscle; if it is punctured, an organism cannot breath. Asphyxiation most likely occurs in this situation because although the diaphragm may contract and relax, other substances will flow between the two cavities to fill the pressure void created by the diaphragm. Thus the diaphragm cannot create a vacuum-like situation in the thoracic cavity and the lungs do not expand or or deflate.

Here is the gallbladder, which is usually tucked neatly away inside the lobes of the liver.

Big Mac's liver appear to have four lobes, but in actuality there is another tiny lobe tucked away. Similarly, her lungs appear to have only four lobes, but she really has seven, according to http://www.upt.pitt.edu/ntress/Bio1_Lab_Manual_New/fetal_pig_respiratory_intro.htm. //N.B.// Unfortunately, the thymus glands were sacrificed in the process of reaching the trachea. Their remains are evident on the left and right side of the trachea, however; they appear as knotty tissue.

=**The Digestive System**=

As illustrated above, the mouth is a rather complex structure. Directly behind the epiglottis is the glottis, which leads to the larynx and then the trachea. If Big Mac were to swallow, the epiglottis would cover the glottis, thus preventing any bits of food from entering the "wrong pipe."

Here is a portion of the esophagus that is just superior of the stomach. It leads dorsal of the liver into the stomach.

Above is the stomach with a lateral incision, exposing its inside. Ruggae, or folds, are commonly found within.

The main reason for the picture above is to show the pancreas, which was hidden behind quite a bit of tissue. Its primary role is to produce insulin, sodium bicarbonate, and a digestive juice cocktail that aids in digesting all sorts of substances.

Here the connection between the small intestine and the large intestine is visible; also present is the caecum, which branches out from the large intestine directly after this juncture.

Although we don't have a picture of the rectum, it is simply the end of the large intestine running along the dorsal side of the thoracic cavity to the anus.

=The Circulatory System=

The coronary sulcus is the groove running along the heart, denoting the separation of the two ventricles. A prominent coronary artery traces this small indentation. The arteries indicated above are the pulmonary artery and aorta - see below for more details.

Note that the ascending aorta and the pulmonary artery are the two arteries that leave the heart.



Pictured above is the ductus arteriosus, which is the opening that allows blood to pass from the pulmonary artery into the ascending aorta; this shunting of blood to the lungs occurs because the lungs serve no purpose in fetal pigs - they cannot breathe in the womb.

Here are the fringes of the pericardial sac. Unfortunately, most of the sac was torn off in the dissection, but we managed to find this picture from an earlier part of the dissection, showing the fact that it normally surrounds the entire heart. It normally contains fluid, which lubricates the heart so that it can perform its best. The sac also protects the heart itself and helps prevent irregular heartbeats.

=The Excretory System= Unfortunately, some fecal matter oozed from the rectum; this occurrence would explain the green matter on the ureter.

Note the lack of a right kidney - it has been removed for a cross section.

In the above image, the urethra can be seen dorsal to the urinary bladder, leading to the urogenital opening.

The renal cortex appears as a more spongy section, while the renal medulla appears as a more membranous section in the middle. The beginning of the ureter is visible on the bottom of this picture.

Here we have cut away at some of the tissue, exposing the renal pelvis, which leads directly into the ureter. It appears much smoother than the other sections. The ureter actually opens "downwards" in this picture, but the "top" wall of it has been cut away to reveal the renal pelvis.