8 Chapter 8
LAB 8
Basic Mammalian Anatomy
Prepared by Dr. Jeff Ray, Dept. of Biology, UNA
OBJECTIVES
After completing these laboratory activities, you should understand/be able to:
- Have a basic understanding of the steps of a dissection of a mammal, and how the dissection of the fetal pig is a surrogate for the human.
- Identify the structures of the fetal pig as specified by your instructor and know the basic function of each.
- Identify the structures of the human models as specified by your instructor and know the basic function of each.
Introduction
In today’s lab, you will dissect and study the anatomy of the fetal pig^ as a surrogate for the human. The fetal pig is exceedingly similar to the internal human anatomy in multiple aspects. While performing the dissection, keep in mind these structures are present in the same location and serve the same basic function in humans. Be sure to compare the anatomical structures in the pig with the human torso model.
^These pigs were not killed for the purposes of being dissected, but are the by-product of the food processing (pork) industry and would be otherwise be used as fertilizer or thrown away if not used for dissection purposes.
*Instructions* Check off each structure on the worksheet as you find it.*
Work in groups of 2-3. Wear gloves and a disposable apron if you are dissecting or assisting the “surgeon.” If you are not participating, it is your job to read and instruct the surgeon on the proper steps and to make sure all activities are completed. The pigs will be washed, but after opening the body cavity, it will be useful to rinse fluids out of the cavity to better observe internal anatomy. Have paper towels ready and also use Febreze™ to spray the inside of the pig to remove any smell-use liberally. Ask your instructor for assistance.
External Anatomy
All Mammals possess mammary glands and hair. Both pigs and humans are placental mammals, and development occurs within the uterus (in utero). An umbilical cord is the pipeline between the fetus and the placenta. At this interface, oxygen and nutrients are exchanged for carbon dioxide and wastes. Within the umbilical cord, one umbilical vein carries nutrients to the fetus while two umbilical arteries carry wastes away. Pigs and humans are also both tetrapods–four-limbed vertebrates. Pigs actually walk on their toes (their toenails are hooves). Notice the bones of the ankle are halfway up the hind leg.
*What key features define pigs and humans as mammals? _____________________________________
*Securing the Pig to the Dissection Pan*
1. Place the pig on its back in the pan. Tie a string around one front leg, then bring the string underneath the pan, and tie the string to the other front leg. Do not tighten the knot until you have removed any slack from the string or the pig will not stay in place.
2. Repeat this process for the back legs- tie a string around one back leg, bring the string underneath the pan, and then tie the string to the othe