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Procedure (a) labelled diagram of pig as per Figure 1 in the Student Text (b) Answers will vary. See Figure 2 in the Student Text. (c) labels added as per Figure 3 in the Student Text (d) The umbilical cord carries oxygenated blood from the placenta to the pig through the umbilical vein. It carries deoxygenated blood to the placenta through the umbilical arteries. 116 Unit 3 Student Book Solutions NEL (e) Features should be added and labelled as they appear on students’ pigs. (f) diagram labelled as per Figure 4 in the Student Text (g) tongue: manipulates food during chewing and moves food to the back of the mouth for swallowing esophagus: muscular tube that carries food from the mouth to the stomach epiglottis: flap that prevents food and water from entering the trachea trachea: airway from the oral cavity into the chest cavity; splits into two bronchi, one going into each lung (h) the stomach (i) labelled diagram as per Figure 6 in the Student Text (j) The cardiac sphincter prevents food from leaving the stomach and entering the esophagus. The opening and closing of the pyloric sphincter controls the movement of food from the stomach into the small intestine. (k) The pancreas produces digestive enzymes as well as the hormone insulin. (l) Answers will vary with the size of the pig. The small intestine is much longer than the large intestine. Labels of kidney, caecum, pancreas, and gallbladder should be added to students’ diagrams. (m)The kidneys are covered in tissue that attach them to the abdominal wall and are located underneath the intestines. (n) labelled diagram as per Figure 8 in the Student Text (o) labelled diagram as per Figure 7 in the Student Text (p) The lungs are soft and spongy in texture. Note that the preservative makes the lungs more rubbery than would be the case in a fresh specimen. (q) The trachea is firm but highly flexible— much like a vacuum cleaner hose. The cartilaginous rings prevent the trachea from collapsing during inhalations while maintaining a flexible structure. Analysis (r) It is important to wear rubber gloves, a laboratory apron, and safety goggles during dissections. In addition, extra care must be taken to avoid being cut by the extremely sharp dissecting instruments— scalpels, scissors, forceps, etc. Cleanliness is also very important. Dissected body tissues must be properly disposed of and a clean working area must be maintained. Between dissections the specimens must be kept well preserved to prevent possible decay. (s) The liver performs many important functions including the breakdown of red blood cells and the formation of bile, the detoxification of harmful and foreign substances, deamination of amino acids and as a storage organ for various nutrients including glycogen and vitamin A. (t) Organ Location Function gallbladder on the under surface of the right lobe stores and releases bile through the bile duct of the liver to the small intestine spleen on the left side of the body within the helps produce and maintain red blood cells abdominal cavity just posterior to the stomach small intestine a coiled tube within the abdomen connecting digestion and absorption of food nutrients the stomach to the large intestine large intestine a coiled tube within the abdomen connecting recovery of water from digestive tract; the small intestine to the anus formation and expulsion of solid wastes larynx at the top of the trachea just below voice box for producing sounds the esophagus kidneys on the dorsal internal abdominal wall remove wastes, unwanted solutes, and excess water from the blood stomach just below posterior to the liver within digestion of food, “acid bath” to kill off the abdominal cavity microorganisms and partial liquefaction of the food (u) The great length of the small intestine increases its surface area for absorption and allows food to be in the intestine long enough to permit efficient digestion and absorption. (v) right atrium and right ventricle— deoxygenated; left atrium and left ventricle— oxygenated (w)The stiff rib cage in necessary for the mechanics of breathing. Expanding and contracting the volume of the thoracic cavity creates air pressure differences which result in inhalation and exhalation. In contrast, the softer abdominal wall permits the belly to distend when large quantities of food are ingested and/or during pregnancy. (x) The fetus obtains its oxygen supply from the placenta. The lungs need only enough blood to supply the lung tissues directly with the oxygen and nutrients they require for growth. NEL Unit 3 Performance Task 117 (y) Immediately at birth the baby pig must begin to use its lungs. This requires the large blood supply to be cut off in the umbilical cord and redirected to the lungs. (z) A heart G liver B diaphragm H stomach C gallbladder I spleen D small intestine J pancreas E bladder K large intestine F lung Evaluation (aa) Fetal pigs are good models for human anatomy because they have an omnivorous diet similar to that of humans. They are also readily available and relatively large. (bb) Answers will vary. The circulatory and reproductive systems can be difficult to observe in fine detail. In addition, the nervous system is very challenging to dissect as the main components are encased within the bones of the cranium and spinal column. (cc) Answers will vary. The dissection might benefit from the use of a dissecting microscope or fresh specimens rather than preserved animals. Larger pigs have more fully developed organs. Synthesis (dd) (i) W e have very similar organ systems. Although they differ somewhat in size, each organ/tissue found in humans has a homologous one in the pig. (ii) The most significant differences are in human brain size/development and our bipedal locomotion with highly dextrous hands. Students will note the differences in reproductive organs too. (ee) This permits acidic stomach contents to enter the esophagus. The lining of the esophagus has only a thin mucus layer for protection and can be irritated and or seriously damaged by the stomach acid. (ff) The kidneys lie directly against the dorsal surface of the abdominal wall and could be easily accessed through the back wall. Extension (gg) The entire vertebral column and brain can be exposed through careful dissection. This will likely require an additional full period or time outside of class. Bone cutters or strong scissors will be required.