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Name: ______McClanahan______________________________ Class: __Key______ Fetal Pig Dissection MATERIALS (per group) latex free gloves goggles lab aprons dissecting pan (1) dissecting scissors (1) dissecting probe (1) forceps (1) dissecting pins (6) fetal pig specimen PRE-LAB Questions https://www.whitman.edu/academics/departments-and-programs/biology/virtual-pig Anatomical References The following terminology will be used to identify the location of body parts throughout the dissection. anterior – towards the head ventral – towards the belly posterior – towards the tail proximal – lying near the point of reference dorsal – towards the backbone distal – lying further from the point of reference Using the virtual dissection, label the above terms on the three different pigs below. Anterior Dorsal Posterior Ventral V Proximal Distal Sexing Your Pig/ External Anatomy 1. How can you tell the gender of a fetal pig? Urogenital Papilla (Opening) is in different spots. 2. Where is this structure located on the fetal pig? - Male papilla is just posterior to the umbilical cord - Female papilla is in front of the anus 1 3. What is the function of the skin? Protection, temperature regulation, as well as the external receptors to environmental stimuli. Digestive System Questions 1. Write the name of each structure through which food travels in the digestive system (in the correct order). Mouth, esophagus, stomach, small intestine, large intestine, rectum, anus. 2. What are the structures that aid in digestion but food does not travel through? Liver, gallbladder, pancreas 3. What is the function of the tongue? Contributes to chewing, swallowing, and sensing food. 4. What is mechanical digestion? Where does it take place? Mechanical digestion is physical digestion or chewing of food. This takes place in the mouth and stomach. 5. What is chemical digestion? Where does it take place? Chemical digestion is the use of enzymes like those found in saliva and the stomach to break down food. Mouth and stomach. 6. Where does most of the digestion of food occur? Stomach 7. Where does absorption of nutrients from the food occur? Small Intestine 8. What organ houses large amounts of symbiotic bacteria? Large Intestine 9. What is the function of the liver? Production of bile, which helps carry away waste & breakdown fats in the small intestine; production of proteins for blood plasma; production of cholesterol to help carry fats through the body; glucose to glycogen to help regulate blood sugar levels; processes blood that leaves stomach & intestines & breaks down nutrients; produces urea for the production of urine. 10. What is the function of the pancreas? Produces the hormone insulin which promotes sugar uptake from blood. Excretory System Questions 1. What is urine? a watery, typically yellowish fluid stored in the bladder and discharged through the urethra. It is one of the body's chief means of eliminating excess water and salt and also contains nitrogen compounds such as urea and other waste substances removed from the blood by the kidneys. 2. What is the function of the kidneys? To separate urea, salts & toxins from the blood. Circulatory System Questions 1. What four major things does the circulatory system transport? Oxygen, CO2, nutrients & hormones (chemical messengers) 2 2. Why is a four-chambered heart the most efficient? Separates the oxygenated and un-oxygenated blood. Reproductive System Questions 1. What is the function of the testes? Produce sperm & testosterone 2. What is the function of the ovaries? Produce eggs & estrogen 3. Other than gametes, what else do the ovaries and testes produce? Hormones 4. What other body system would ovaries and testes function in based on the answer to question 3. Endocrine System Respiratory System Questions 1. What gas is inhaled into the lungs? Oxygen 2. What gas is exhaled out of the lungs? Carbon dioxide 3. What is the function of the diaphragm? How does it work? The function of the diaphragm is to aid in respiration. As the diaphragm moves down, the lungs can take in air. When the diaphragm moves up, it pushes CO2 out of the lungs. 4. Explain how the circulatory and respiratory systems are interdependent upon each other. The respiratory system exchanges gases with the circulatory systems and the circulatory system transports those gases. Nervous System Questions 1. What is the function of the spinal cord? The spinal cord carries out two main functions: It receives information from the external or peripheral nervous system and sends those impulses (messages) to the brain; transmits signals from the central nervous system (brain) to the rest of the body. 3 LAB DISSECTION PROCEDURES – make sure a lab apron and goggles are worn the entire time External Anatomy 1. Place the pig on its side in the tray as shown in figure 1. 2. Use figure 1 to locate the following external structures on your pig: thorax, abdomen, umbilical cord, external nares (nostrils) Head Region Neck Thorax Region Abdomen Tail Region Figure 1. Color Key teats Digestive = brown Circulatory = red Reproductive = blue Respiratory = green Excretory = yellow Nervous = orange Skeletal = purple Integumentary = pink Immune = black umbilical cord 3. Place the pig in the tray ventral side up as shown in figure 2. 4. Use figure 2 to locate the following structures on your pig: nipples (teats), urogenital opening, and scrotal sac (males only). Based on external features, what is the gender of your pig? _________________________ Figure 2. Female Male Color Key Digestive = brown Circulatory = red Reproductive = blue Respiratory = green Excretory = yellow Nervous = orange Skeletal = purple Integumentary = pink Immune = black teats (nipples) umbilical cord urogenital opening urogenital papilla scrotal sac 4 Internal Anatomy – Digestive System 1. Place the pig in the dissecting tray ventral side up. Pry open the mouth using a dissecting probe. 2. Using scissors, cut through the joint between the upper and lower jaws to aid in observations. 3. Find the tongue and notice the taste buds on the tongue. Does your pig have teeth? _________ 4. Using figure 4, locate the pharynx, the mouth cavity that begins at the jaw hinges and extends to the esophagus. 5. Locate the esophagus in the back of the pharynx. 6. Use dissecting pins to pin each of the limbs of the pig down to the tray. 7. Use dissecting scissors to make the initial incisions as directed by figure 3. You can avoid cutting into the underlying organs by pulling up the umbilical cord with the forceps as you cut. It is better to carefully cut twice rather than damage the organs beneath the muscles with one deep cut. Caution: The initial cut may cause preservative to spurt or splash out. 8. Use dissecting pins to pin open the abdominal cavity of the pig flat on the tray. 9. If you have excess fluid in the abdominal cavity, rinse your pig at the sink. 10. Using figure 4, locate the liver. Notice that the umbilical vein runs from the liver to the umbilical cord. You will need to cut the umbilical vein to pin down the area that contains the umbilical cord. 11. You will need to remove the liver in order to see many of the digestive organs. Ask your teacher for help if you are having problems removing the liver. 12. Using figure 4, identify the following structures of the digestive system on your pig: esophagus, stomach, small intestine, large intestine, rectum, liver, gall bladder, and pancreas. (Note: the gall bladder is the pouch located beneath the liver; the pancreas is the cottage cheese-looking structure beneath the stomach) 13. Using your forceps or dissecting probe, separate the folds of the small intestine and notice the mesentery that holds it together. Figure 3. 5 Figure 4. tongue opening to pharynx taste buds larynx esophagus thymus gland trachea right atrium left atrium lung rib cage coronary artery right ventricle left ventricle coronary artery diaphragm liver stomach spleen pancreas small intestine large intestine caecum mesentary urinary bladder umbilical artery umbilical vein region of anus rectum Color Key Digestive = brown Circulatory = red Reproductive = blue Respiratory = green Excretory = yellow Nervous = orange Skeletal = purple Integumentary = pink Immune = black 6 Internal Anatomy – Circulatory & Respiratory Systems 1. To identify structures of the circulatory and respiratory systems, you will need to open the chest (thoracic) cavity. Use dissecting scissors to carefully cut through the ribs and sternum. Using dissecting pins, pin open the thoracic cavity of the pig. 2. Remove the thymus gland so that the chambers of the heart will be accessible. 3. Using figure 4, identify the following structures of the circulatory system on your pig: right atrium, right ventricle, left atrium, and left ventricle (note: if your pig has been injected with latex dyes, the arteries will be red and the veins will be blue) 4. Using figure 4, identify the following structures of the respiratory system on your pig: trachea, lungs, and diaphragm Internal Anatomy – Excretory & Reproductive System 1. To identify structures of the excretory and reproductive systems, you will need to open the lower abdominal cavity. Use dissecting scissors to carefully cut the lower abdominal cavity. Using dissecting pins, pin open the lower abdominal cavity of the pig. 2. Using figure 5, identify the following structures of the excretory system on your pig: kidney, ureter, urinary bladder (remember that the urinary bladder is located within the umbilical cord) 3. Using figure 5, identify the following structures of the reproductive system on your pig: ovaries, fallopian tubes, uterus (if female). If you have a male pig, open the scrotal sac to locate the testes. Figure 5. Color Key Digestive = brown Circulatory = red Reproductive = blue Respiratory = green Excretory = yellow Nervous = orange Skeletal = purple Integumentary = pink Immune = black kidney ureter ovary fallopian tube uterus urinary bladder ovary testes urethra scrotal sac Clean up: Remove the pins from your pig Dispose of your pig and all organs/tissues in the appropriate trash bag. Wash (with soap!) and dry the dissecting area, tray, and dissecting instruments. Throw away gloves & paper towels in the appropriate trash bag. Thoroughly wash your hands. Return goggles and lab apron. 7