SBI3U1 page 1 Examining the Systems of the Fetal Pig Introduction Pigs are members of the class Mammalia. Before birth, the young are nourished by the placenta in the mother’s womb. For this reason, pigs (like humans) are known as placental mammals. Although the fetal pig is not yet born, its internal systems are complete. You will be taking pictures and notes to document your dissection in a PowerPoint presentation. Materials safety goggles preserved pig string ruler dissection pins dissecting tray scissors dissection gloves forceps probe Procedures Part A: External Anatomy 1. Place your pig on the dissection tray. Using a ruler, measure the length of the pig from snout to tail. Use the graph to estimate the age of your pig. Record it. 2. Use Figure 2 to identify the four regions of the pig’s body: the head, the neck, the trunk, and the tail. Observe the umbilical cord & paired row of nipples – both males and females have them. Figure 1 3. The location of the urogenital opening is the most obvious method to determine a pig’s gender with an external examination. The female has its urogenital opening just ventral to the anus – as well as a genital papilla. The male has its urogenital opening just posterior to its umbilical chord – as well as two scrotal sacs just ventral to its anus. Take a picture (slide #1) and label all reproductive parts of your pig. Figure 2 Figure 3 Figure 4 scalpel SBI3U1 page 2 5. Examine the mouth and tongue. Does your specimen have any teeth? Touch the tongue and describe its texture with two distinct words. ____________________ ___________________ Part B: Abdominal Cavity (Digestive system) During the dissection you will be asked to examine specific organs as they become visible. Remove only those organs indicated by the dissection procedure. Be careful not to damage underlying structures. 1. With the pig still on its dorsal surface, attach one piece of string to one of the pig’s hind legs, pull it under the dissection pan, and tie it to the other hind leg. Repeat this procedure for the fore legs. 2. Using scissors make the incision indicated by #1 in Figure 5. Start by cutting around the umbilical cord, and then cut straight toward the head (anterior) of the pig. 3. Make incision #2 toward the posterior of the pig. Make incision #3 near the neck, and then incision #4. Make incision #5 that runs parallel to the diaphragm. Incision #5 separates the thoracic and abdominal cavities. Figure 5 4. Pull apart the flaps along incision #5 to expose the abdominal cavity. Use the probe to open the connective tissue (peritoneum) that holds the internal organs to the lining of the body cavity. Use dissection pins to hold the flaps of tissue open. 5. Using Figure 6, locate the liver of your pig. Record the number of lobes in the liver. ___ 6. Using a probe, lift the lobes of the liver to locate the saclike gall bladder. 7. Follow the thin duct from the gall bladder to the small intestine. Bile salts, produced in the liver, and stored in the gall bladder, are released into this duct so that they can emulsify fats in the small intestine. 8. Locate the J‐Shaped stomach beneath the liver. 9. Using figure 6 to help you, locate the spleen. The spleen stores red and white blood cells and removes damaged red blood cells from the circulatory system. 10. Using a probe and forceps, lift the junction between the stomach and small intestine, removing supporting tissue where required. Uncoil the junction and locate the creamy‐white pancreas. The pancreas makes many digestive enzymes and a hormone called insulin that regulates blood sugar levels. Figure 6 SBI3U1 page 3 11. Using a scalpel, remove the stomach from the pig by making traverse (crosswise) cuts near the junction of the stomach and esophagus and near the junction of the stomach and small intestine. Cut the stomach in half and rinse it with distilled water in your dissection tray. View the inside lining of the stomach and take a picture of this with the rest of the abdominal cavity (slide #3). Be sure to also label the liver, gall bladder, pancreas, spleen, stomach, small intestine & large intestine. Record the appearance of the inside lining of the stomach. Was there any food inside the stomach? 12. Locate the small intestine at the posterior (bottom) end of the stomach. Examine the small and large intestine and describe its similarities and differences. Remove about 2cm portion of the small intestine and cut it open like a hot dog bun. Describe in detail the texture inside. Part C: Respiratory System 1. The thoracic cavity is the area located above the liver (see figure 6). The lungs function as a surrounding protection for what important organ? Describe the difference between the right and left lunch. What muscle sits beneath the lungs and separates the thoracic cavity from the abdominal cavity? 2. Locate the thyroid gland (a small, delicate, darker gland) that’s located just on top of the larynx. 3. Place your index finger on the trachea and push downward, record what happens. Record the structure and texture of the trachea. Find the esophagus (directly beneath the trachea). How does the structure/texture of the trachea differ from the esophagus? Take a picture of the thoracic cavity (slide #3) showing both the trachea and esophagus. Label the larynx, thyroid gland, trachea, esophagus, heart, lungs and diaphragm. Part D: Circulatory System 1. Locate the heart – you are seeing the anterior view of the heart. Using forceps and a probe, carefully remove the pericardium (the thin connective tissue covering the heart). What is the function of the pericardium? 2. Using figure 7 to help you, located the inferior and superior vena cava. These veins return deoxygenated blood back to the right atrium of the heart. Take a picture of the attached, anterior view, of the heart (slide #4) 3. Locate the right atrium, right ventricle, left atrium and left ventricle. Make a diagonal incision across the heart to expose the heart chambers. Compare the thickness of the wall of the ventricle compared to the wall of the atrium. Record your observations. Figure 7 SBI3U1 page 4 4. Trace the pathway of the aorta from its arch down along the spine (figure. 8). Note: the esophagus can also be seen. Part E: Reproductive System Find and identify the appropriate reproductive parts of your fetal pig. Be sure to examine the fetal pig of the other sex from another group as you are required to have a basic understanding of both sexes. See figure 9. Male 1. Locate the testes. This is where sperm and testosterone are produced. Figure 8 2. The vas deferens serves to transport sperm to the penis. Identify both of these features on the pig. What two substances are released by the male pig through the penis? Female 1. Locate the ovaries. This is where eggs and hormones (estrogen, progesterone & testosterone) are produced. 2. The oviducts (fallopian tubes) serve to transport the egg to the uterus. The female urogenital opening serves as the exit point for what two substances? Figure 9 All In a Day's Work . . . 1. Carefully remove pins & fetal pig from tray. Wrap the string around the fetal pig and place the pig its original bag. Place it in the appropriate bucket. 2. Place dissecting pins in the beaker with soapy water. 3. Rinse dissecting tray with water and dump waste/dirty water in pig bucket. 4. Rinse all dissecting materials thoroughly in soapy water and dry carefully with paper towel. Place all instruments in the dissecting kit and leave kits open on the teacher's trolley to allow further drying. 5. DO NOT REMOVE ANY MATERIALS FROM LAB! SBI3U1 page 5 FETAL PIG DISSECTION MARKING SCHEME Group Members:________________________________________________________________________ PowerPoint Presentation of Lab Work: PowerPoint slide submitted through D2L e‐learning (Submitted as a group or individually ‐ you decide) Overall Appearance of Slides (Communication) /6 □ title slide contained lab title, full course code & full names □ photos are clear/detailed □ proper order & titles on each slide (shown below) □ diagram clearly labeled with correct word(s) □ all labels also have their correct corresponding numbers (shown below) □ spelling of parts Slide #1: External Examination /4 □ 1. urogenital opening □ 2. umbilical chord □ 3. anus □ 4. genital papilla or scrotum Slide #2: Abdominal Cavity /8 □ 1. liver □ 2. gall bladder □ 3. pancreas □ 4. spleen □ 5. stomach □ 6. large intestine □ 7. small intestine □ 8. stomach cut open Slide #3: Thoracic Cavity /7 □ 1. trachea □ 2. esophagus □ 3. larynx □ 4. thyroid gland □ 5. heart □ 6. lungs □ 7. diaphragm Slide #4: Anterior View of Heart /5 □ 1. right atrium □ 2. right ventricle □ 3. left atrium Application □ 4. left ventricle □ 5. aorta Communication /24
/6 SBI3U1 page 6 FETAL PIG DISSECTION MARKING SCHEME Cont'd Discussion Questions: Thinking (16 marks) Word Document submitted through D2L e‐learning (Submitted as a group or individually ‐ you decide) 1. What is the estimated age of your pig? How do you know? (2 marks) 2. What is the gender of your pig? How do you know? (2 marks) 3. Does your pig have teeth? Describe the texture of the tongue. (2 marks) 4. The liver is the largest internal organ (the skin being the largest organ overall). How many lobes does the liver of the fetal pig have? How many lobes does a human liver contain?(2 marks) 5. Describe the inner lining of the small intestine. How does this relate to its function? (2 marks) 6. What muscle sits beneath the lungs and separates the thoracic cavity from the abdominal cavity? Does the fetal pig use its lungs to breathe while in the mother's womb? Explain. (2 marks) 7. How does the structure/texture of the trachea differ from the esophagus? Explain how each structure relates to its function. (2 marks) 8. Describe the thickness of ventricles vs. atria. Relate the structure to function (2 marks) Overall Appearance of Discussion Questions (Communication) □
title page contains lab title, full course code & full names □
questions are numbered and answered in the proper order □
spelling and grammar □
this marking scheme is submitted with all appropriate group member names /4 Thinking/Inquiry /16
Communication /4 TOTAL LAB MARKS Application /24 Thinking /16 Communication /10