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FETAL PIG DISSECTION - LAB # 3 HEAD REGION, ORGAN REMOVAL, THE CIRCULATORY, EXCRETORY AND RESPIRATORY ORGANS PSSA Standards for Reading, Writing, Speaking, Listening, Science and Technology ASRWSL 1.1F = Understand the meaning of and apply key vocabulary across the various subject areas. ASRWSL 1.2A = Read and understand essential content of informational texts and documents in all academic areas. ASRWSL 1.6A = Listen to others. ASRWSL 1.6D = Contribute to discussions. ASRWSL 1.6E = Participate in small and large group discussions and presentations. ASST 3.2 C = Apply the elements of scientific inquiry to solve problems. ASST 3.3 A = Explain the structural and functional similarities and differences found among living things. ASST 3.7 A = Identify and safely use a variety of tools, basic machines, materials and techniques to solve problems and answer questions. MATERIALS: scalpel safety goggles / glasses forceps (tweezers) Fetal Pig Reference Diagram Booklet scissors lead & colored pencils probe bone cutters (needed to sever head) pig hand lens (needed for last step of lab) dissection pan lined with paper toweling 1 rough draft diagram entitled: SALIVARY GLANDS – ORAL/BUCCAL CAVITY 1 rough draft diagram entitled: HEART – VENTRAL / DORSAL / INTERNAL VIEWS 1 rough draft diagram entitled: EXCRETORY AND RESPIRATORY STRUCTURES GENERAL INFORMATION: This lab is divided into the following four parts: PART I = You are going to locate, draw and label several structures of the head region of the fetal pig. PART II = You are going to open the thoracic (chest) and abdominal cavities of the pig and then locate the organs found in these cavities. PART III = You are going to complete several tasks: remove the internal organs as one unit, sever the head from the rest of the body, dispose of the body, separate the single unit of organs into four parts, and skin the head. PART IV = You are going to locate, draw, dissect and label the heart, lungs and kidneys. The labeled, colored diagrams completed in PART I will be kept in your pig folder and turned in with the next lab report (Lab #4). The labeled, colored diagrams completed in PART IV will make up the lab report for this portion of the fetal pig dissection. PART I Use the rough draft diagram entitled: SALIVARY GLANDS - ORAL / BUCCAL CAVITY. Salivary Glands REFER TO DIAGRAM # 12 in the Reference Diagram Booklet. You are now going to locate two types of salivary gland in the fetal pig. They are the parotid and submaxillary (also called mandibular) glands. 1). Turn the pig on her / his side so that you can see the masseter (cheek) muscle you exposed in the last lab. You may have to remove some additional skin at this time, so that the glands are completely exposed. The parotid gland is thin and "C" shaped. The surface of this gland has a “curly” appearance (similar to the top of raw broccoli in texture). It is located below the ear and continues to the throat area. The submaxillary gland is anterior to the parotid gland. It is roughly oval in shape, looks like a bean and lies along the curve of the jaw. You will only see the tip of this gland. Both glands are posterior to the masseter muscle. 2). On the picture entitled SALIVARY GLANDS, draw and label the masseter muscle, the parotid gland and the submaxillary gland. Include the fibers in the masseter muscle. Oral / Buccal Cavity REFER TO DIAGRAM # 13 in the Reference Diagram Booklet. 3).With your scissors, cut through the corner of the mouth - on each side – toward the ear. You will completely cut through the jaw. It will crunch when you do this. When these cuts are complete, the jaw will drop and expose the entire tongue and epiglottis. Refer to the diagram booklet for the location of these structures. This will allow you to examine the interior of the oral cavity. Now locate the structures listed below. Do not draw anything at this time. A. vestibule = This refers to the space between the inside of the lips and teeth. B. tongue = The tongue is an elongated, muscular structure that lies on the floor of the mouth. The surface of the tongue is covered by projections called sensory papillae. The papillae may vary in shape. A large number of fibrous papillae are located along the anterior edge of the tongue (NOTE: These are shown as the rippled edge of the tongue on your diagram.) Microscopic taste buds are found at the sides and base of the papillae. C. teeth = In most fetal pigs the tips of one or two exposed teeth are visible on each side of the upper jaw. You may also see them on the lower jaw if you move the tongue. D. palate = This structure forms the roof of the mouth. It is actually a partition that separates the nasal cavity from the oral cavity. It is divided into two regions: I). hard palate = This is the bony anterior portion of the palate. It is formed by the palatine bones of the skull. It contains a series of transverse ridges, called palatine rugae that run across the roof of the mouth (left to right). II). soft palate = This is the muscular posterior portion of the palate. It is supported by bone but not formed from bone. It is not rigid like the hard palate. There is a hole in the posterior portion of the soft palate. It is the opening of the nasal passage or naso-pharynx. It connects with the opening of the respiratory tract or oro-pharynx. E. epiglottis = If you cut the jaw correctly, you can see the epiglottis. It is a cone-shaped flap of cartilage. It appears to extend from the back of the tongue but it is really a separate structure located at the top of the larynx (voice box). The epiglottis protects the slit-like opening (glottis) into the trachea or "windpipe, which is the passageway into the lungs. During eating and swallowing, the epiglottis covers the glottis so that food does not enter this passageway. The following structures are already on the ORAL / BUCCAL CAVITY diagram: the upper and lower lips (speckled), the space that forms the vestibule, the outer edge of the tip (papillae) and sides of the tongue. Complete the diagram by adding the epiglottis and the back of the tongue. Also add the structures to the roof of the mouth and the back of the throat. Include teeth only if they are present and then label the structures listed next. Use brackets to indicate the hard and soft palates. Labels: vestibule teeth (if present) hard palate palatine rugae soft palate opening of naso-pharynx epiglottis tongue papillae 4). Now sever the pigs lower jaw and tongue from the rest of the body but do not remove the epiglottis with the tongue. Wrap the lower jaw / tongue in paper toweling and discard it. 5). Each person in the group should now complete a final draft of the SALIVARY GLANDS – ORAL/BUCCAL CAVITY diagram in the following way: SALIVARY GLANDS= Use either a black colored pencil or black ink to outline and label the three structures. Use either a black colored pencil or black pen and a ruler to draw lines from the labels to the structures. The lines should not cross over each other. Use black colored pencil or black ink to draw in the masseter muscle fibers. Color both glands yellow. ORAL / BUCCAL CAVITY = Use either a black colored pencil or black ink to outline and label the structures. Use either a black colored pencil or black pen and a ruler to draw lines from the labels to the structures. The lines should not cross over each other. 6). Put the final draft copies in your pig folder. You will turn them in with the next lab (Lab #4). PART II Opening the Body Cavities and Locating the Organs REFER TO DIAGRAM # 14 in the Reference Diagram Booklet NOTE: Some specimens may contain excess preservative fluid and coagulated blood that has escaped from blood vessels. It is a reddish-brown material / liquid located within the body cavity. If you observe this in your pig as you begin to open the abdominal cavity, do the following once the body cavity has been opened: take the dissection pan containing the pig to a sink, adjust the water so that is flows gently, remove the pig from the pan and rinse it out. Use paper towels to soak up any excess water and then continue with the dissection. 7). With your fingertips, locate the lower edges of the ribs. Your fingertips should trace an arc that corresponds with incision #1 on diagram #14. With either the scalpel or scissors, cut incision #1 in your pig. DO NOT CUT TOO DEEPLY!!! The internal organs are easily damaged. Directly below the muscle, there is a thin membrane which lines the body cavity. It is called the (parietal) peritoneum. You may have to cut through this if you did not cut it along with the muscle. The internal organs may also be surrounded by a thin membrane called the visceral peritoneum. Carefully make the remaining incisions (#2 through #6). Extend incision #5 to the epiglottis that you exposed during PART I of this lab. 8). In order to completely expose the body cavity, some of the diaphragm will have to be cut away. The diaphragm is a dome-shaped muscular wall in the region of incision #1. It separates the thoracic (chest) cavity from the abdominal cavity. Locate the diaphragm. Two major blood vessels and the esophagus pass through the diaphragm. Therefore, you must dissect it carefully so that these structures are not damaged. REFER TO DIAGRAMS # 15, the picture opposite # 15, & # 16 in the Reference Diagram Booklet, as you locate the following structures. DO NOT CUT ANY ORGANS AT THIS TIME!!! A. liver = The liver is dark brown and located in the upper abdomen. It is divided into five sections or "lobes". Four of the lobes can be seen from this view. They are the left and right lateral lobes and the left and right central lobes (refers to the pigs left and right). A very small lobe called the caudate lobe is attached to the posterior surface of the right lateral lobe. It can be seen if the coils of the intestine are moved aside. B. gall bladder = Lift the pig’s right (your left) central lobe of the liver to observe the gall bladder. It is pear-shaped and embedded in the under side of the liver. It stores bile secreted by the liver. C. stomach / esophagus = The stomach is a pouch-like structure that lies on the pig’s left (your right) side of the upper abdomen. It is under the liver. Anteriorly, it connects with the esophagus. The esophagus is a muscular tube that passes through the diaphragm on the dorsal side and extends to the oral cavity. D. small intestine = The small intestine is composed of three parts: duodenum, jejunum and ileum. The duodenum is the first part of the small intestine. It is a short "U-shaped" tube about 1 cm. long. The second part is called the jejunum. It makes up about half of the small intestine. The ileum forms the rest of the small intestine. The three parts look alike from this view. The coils of the small intestine are held together by a thin membrane called "mesentery". E. large intestine = The end of the ileum connects with the large intestine (colon). At this junction, there is a short blind sac (looks like a small pouch) called the cecum (caecum = Latin spelling). It is about 2 cm. long. In some organisms, (ex. horses) this is enlarged and houses microorganisms which digest cellulose. In humans, the vermiform appendix projects from the end of a short cecum. The colon is a compact coiled mass of tubing on the pig’s left (your right) ventral surface. It is shorter, darker and thicker than the small intestine. It is the major portion of the large intestine. The posterior dorsal portion of the large intestine is the rectum. It descends along the midline to the anus. The colon is not coiled and shorter in humans. F. pancreas = The pancreas is a gland. The surface of this gland is like the parotid gland. It has a “curly” appearance (similar to the top of raw broccoli in texture). Its main portion lies in the loop of the duodenum. An elongated portion extends toward the stomach, and parts can be seen along the dorsal body wall. It is lighter in color than the intestines. The human pancreas is more compact. G. spleen = This is a dark colored, elongated organ on the left side of the abdominal cavity. It lies to the left of the stomach along its "greater curvature" (outer curve of stomach). It is attached to the stomach by a specialized fold of peritoneum called the "gastrosplenic ligament". The spleen looks like a dog’s (or cat’s) tongue. H. heart and lungs = These structures are found above the diaphragm. The heart is in the center and surrounded by an opaque, white membrane. The lungs are on each side of the heart. They are often pinkish-tan in color and divided into sections called lobes. I. kidneys = There are two of these structures. They are shaped like "kidney beans". They are dorsal to the small intestines. You will have to move the intestines to see them. There is one on each side of the vertebral column. They are outside the peritoneum against the muscles of the back. PART III Removing the Internal Organs and Head from the Rest of the Body REFER TO DIAGRAM # 16A in the Reference Diagram Booklet. 9). Cut away the ribs and muscle in the upper chest and throat regions. You should be able to see the heart and the major blood vessels that extend out of the heart. The vessels look like thick dental floss. Locate the trachea (looks like vacuum cleaner hose) and the larynx that is attached to the top of the trachea. The larynx looks like a shield once you have removed all of the muscle from its surface. The epiglottis forms the top of the larynx. Sever the common carotid and subclavian arteries. You are now going to remove all of the internal organs in one unit. (You will separate the unit into four parts later.) The organs are anchored to each other and to the body wall by membranes which will have to be cut as you proceed. 10). Start by loosening the larynx, trachea and esophagus from the dorsal body wall. The esophagus is a narrow tube that runs dorsal to, and parallel with the trachea. Continue toward the posterior end, keeping the heart / lungs, descending aorta, alimentary canal and kidneys together in one unit. You will have to cut more of the diaphragm to free this unit of internal organs from the rest of the body. Sever the large intestine (colon) as close to the anus as possible. You may also have to sever some additional smaller vessels in this area. This should allow you to remove the organs from the rest of the body. Set the “unit” of organs aside. 11). Using bone cutters, sever the head from the body at about the fourth vertebra. There should be two to three inches of neck attached to the head. Save the “unit of organs” and the head of the pig. Wrap the rest of the body and the skin in paper toweling and discard it in the appropriate (respectful) manner. NOTE: The next two parts: Separating the Organs and Skinning the Head may be completed in sequence, or they may be done simultaneously by two different members of the dissection group. Separating the Organs 12). Place the "unit" of organs in the dissection pan so that the dorsal side (backbone side) of the lungs faces the ceiling. You will see a light colored tube. This is the large blood vessel (aorta) that extends from the heart, down the backbone toward the hind legs. Underneath – and attached to – the aorta there is another thin tube. This tube is the esophagus. Carefully separate the aorta and esophagus from each other and from the rest of the organs without cutting them. 13). Trace the aorta from where it leaves the heart to the opposite end. Cut it so that about two inches of aorta remains attached to the heart. Trace the esophagus from where it connects to the stomach to the opposite end. Cut it so that about two inches of esophagus remains attached to the stomach. 14). Separate the heart and lungs (includes trachea and larynx) from the rest of the organs by cutting mesentery and any remaining diaphragm. 15). Separate the kidneys from the remaining organs by cutting mesentery and separate the liver (includes the gall bladder) by cutting mesentery and a blood vessel. The organs that are left form the alimentary canal (digestive tube). The internal organs should now be divided into the following four parts: A). heart / lungs (includes trachea & larynx) B). kidneys C). liver / gall bladder D). alimentary canal . Skinning the Head 16). Using the diagram below as a guide, remove the skin (including the external ears) and as much muscle as possible from the head and neck. When you are done you should be able to see the skull and vertebrae. The vertebrae will look like a stem coming out of the back of the skull. Completely remove the skin and muscle from the head and neck in this area. Leave the skin on the snout and around the eyes (speckled area). 17). At this point, you will receive a new pig bag and fresh brine. Thoroughly rinse the heart / lungs, kidneys, liver / gall bladder, alimentary canal, and head of the pig before placing them in the new bag. Wrap the skin and muscle you removed from the head in paper toweling and discard it. PART IV Heart REFER TO DIAGRAM # 15, # 17 and # 19 in the Reference Diagram Booklet. NOTE: The ventral side of the heart is the front of the heart. Therefore, the dorsal side is the back of the heart. The references to left and right refer to the pigs left and right. When labeling ventral view diagrams the words left and right must be reversed from the way you observe them. 18). The heart is located between the lungs and ventral to (in front of) the trachea. It is surrounded by a thin, opaque membrane called the pericardial sac. The thymus gland is a mass of tissue that sits on top of the heart. It looks similar to the other glands you have seen during the dissections (texture of raw broccoli). Refer to diagram # 15. Even though the heart is still inside the body, you can see the pericardial sac and thymus gland. Also look at the left picture on diagram page # 19. This is a similar view of the heart after the organs are removed. Now carefully cut away as much of the pericardial sac and thymus gland as possible. 19). You are now going to separate the heart and major blood vessels from the larynx / trachea and lungs. Locate the aorta. This is the large blood vessel (light colored and tube-shaped) that extends out of the top of the heart. Bring this over the ventral side (front) of the heart. You should be able to see a space between the dorsal side (back) of the heart and the trachea. The trachea looks like vacuum cleaner hose. You may need to use the probe to find this space. Small blood vessels extend from the back of the heart into the lungs. Sever these small blood vessels and you should be able to separate the heart from the larynx / trachea / lungs. Set the larynx / trachea / lungs aside. 20). Refer to the left picture on diagram page # 17. Hold the heart so that you are looking at the ventral side (front). It has two auricles (also called atria – sing. atrium) and two ventricles. The auricles look like two pouches that sit on top of the ventricles. Externally, the ventricles appear as one structure. You can also see the coronary artery on the surface of the heart. It runs diagonally across the ventricles. It supplies the heart muscle itself with blood. The large pulmonary trunk, which is the beginning of the pulmonary artery, is seen leaving the heart from the ventral surface and extending to the pigs left (your right) side. This vessel and the aorta are arteries. Therefore, they are round and the walls are thicker. The aorta leaves the heart from behind the pulmonary trunk and also extends to the pigs left side. In the fetal pig, the pulmonary trunk is joined directly to the aorta by means of a short vessel known as the ductus arteriosus. This connecting link is present until birth. It serves as a bypass so that the blood goes back into the circulatory system. It does not travel to the lungs for oxygen since the animal is not yet breathing air. At birth, the ductus arteriosus shuts tightly, separating the two major blood vessels. This allows the blood to circulate to the lungs for gas exchange. 21). Turn the heart so that you are looking at the dorsal side (back). Both of the vena cavas are veins. Therefore, they are very thin walled tubes and do not look like blood vessels. They look more like membranes. The caudal vena cava returns blood from the posterior portion of the body and carries it into the right atrium. In man, it brings blood from the lower portions of the body (legs) and is called the inferior vena cava. A similar but shorter vessel is seen anterior to the heart. This is the cranial vena cava. It carries blood from the head and forelimbs. In man, it is called the superior vena cava and carries blood from the head and upper portions of the body. It also enters the right atrium. There are additional, small pulmonary arteries and veins that extend directly into the lungs. USE THE ROUGH DRAFT DIAGRAM ENTITLED: HEART – VENTRAL / DORSAL / INTERNAL VIEWS. 22). Draw the ventral view of your pig’s heart in the designated area. Label the following structures: left and right ventricle pulmonary trunk left and right auricle aorta coronary artery cranial vena cava 23). Draw the dorsal view of your pig’s heart in the designated area. Label the following structures: left and right ventricle cranial vena cava left and right auricle caudal vena cava aorta Internal Anatomy of the heart REFER TO DIAGRAM #18 in the Reference Diagram Booklet. You are now going to take a slice off the front (ventral side) of the heart so that you can see into all four chambers. Read ALL of the instructions first. If you do not understand how to complete the cutting procedure – ask before you cut! 24). Turn the heart upside-down so that the bottom tip of the ventricle faces the ceiling and the auricles are on the bottom of the pan. You should be looking at the ventral side. Using a sharp scalpel, You are going to slice the front off both auricles and both ventricles so that you can look inside all four chambers. To accomplish this, remove about 1/3 of the ventral side by cutting from the tip of the ventricle toward the bottom of the pan. Look into the remaining 2/3 of the heart. Normally, there is coagulated blood inside the chambers. It is reddish brown and ranges from paste-like to solid in consistency. Remove it and rinse out the inside of the heart. Hold the heart so that the auricles are on top. It should look like the left picture on diagram page # 18. 25). Locate the following structures: left and right auricles, left and right ventricles, pulmonary trunk and aorta. If the aortic valves are present, you will see from one to three small flaps (depending on your “cut”). They are inside the artery (aorta) where it connects with the ventricle. The open ends of the valves face into the aorta. This means that any backward flow of blood from this artery into the ventricle will fill the valves with blood so they make contact with each other to prevent the back flow. 26). Between the right (pig’s right) auricle and ventricle, there are three flaps of tissue. This is the tricuspid valve. Pass a probe through the valve and note that the probe emerges into the right ventricle. The internal walls of the ventricle show muscular ridges called papillary muscles. Extending from these muscles are fibers that look like threads. They are called chordae tendinae and are attached to the edges of the valves. They control the opening and closing of this valve. Repeat this procedure with the left auricle and ventricle. Locate the bicuspid or mitral valve between the left (pig’s left) auricle and ventricle. Probe into the aorta from the outside of the heart. Note that the probe enters the left ventricle. The aortic valve (if present) is at the junction of the aorta and the left ventricle. The muscular wall between the two ventricles is the septum. Draw the internal view of the heart in the designated area. Remember that the bicuspid and tricuspid valves actually separate the auricles from the ventricles. Label the following: left and right auricle left and right ventricle bicuspid / mitral valve tricuspid valve pulmonary trunk aorta aortic valve (optional) You have now finished the diagram named: HEART – VENTRAL / DORSAL / INTERNAL VIEWS. STOP AND CHANGE DIAGRAMS To finish the lab, use the diagram named: EXCRETORY AND RESPIRATORY STRUCTURES. Kidneys 27). Cut a kidney in half lengthwise (similar to the way you cut the heart open). The spongy outer area is called the cortex. The white membranous central portion is the renal pelvis. Liquid waste collects here. Draw the inside of the kidney in the designated area. Label the following: cortex and renal pelvis Larynx / Trachea / Lungs REFER TO DIAGRAM # 19 in the Reference Diagram Booklet. 28). Examine the lungs. The lungs of the fetus are firmer than the spongier lung tissue found after birth. Remove any excess tissue or muscle from the larynx. When you are finished it should look like a shield. The epiglottis is the small flap at the top of the larynx. Lay the larynx / trachea / lungs so that the ventral side of the trachea faces the ceiling (left picture on diagram page # 19). The larger, right (pig’s right, your left) lung is divided into four lobes. The anterior lobe (lobe closest to the larynx) is called the right apical lobe, the lobe posterior to it is the right cardiac lobe and the lobe below this is the right diaphragmatic lobe. There is a fourth, smaller lobe called the intermediate lobe. It extends from the right diaphragmatic lobe. The left lung is divided into three lobes: the left apical, cardiac and diaphragmatic lobes. The left apical lobe is small and looks like the top tip of the cardiac lobe. 29). Draw this view of the larynx / trachea / lungs in the designated area. Label the following: epiglottis left cardiac lobe larynx right cardiac lobe trachea right diaphragmatic lobe left apical lobe left diaphragmatic lobe right apical lobe intermediate lobe 30. Cut a small section off of the lung and observe it under the hand lens. The small holes are the bronchioles surrounded by the lung tissue. Draw this view of the lung section in the designated area. Label the following: bronchioles and lung tissue FETAL PIG DISSECTION LAB REPORT # 3 (70 points): THIS IS NOT A GROUP LAB REPORT. EACH PERSON IN THE CLASS MUST TURN IN A LAB REPORT. This lab report consists of two final draft diagram pages. Directions for the diagrams follow: Each person in the group must have two diagrams to turn in. Photocopies receive zero credit. The diagrams are graded according to the following criteria: accuracy of the drawings neatness and correct spelling of labels accuracy and legibility of labels following the directions 1). Once you complete both rough draft pages, get a clean copy of each page to make your final drafts. 2). PAGE 1 – HEART – VENTRAL / DORSAL / INTERNAL VIEWS VENTRAL VIEW= Use either a black colored pencil or black pen to outline and label the structures. Use either a black colored pencil or black pen and a ruler to draw lines from the labels to the structures. The lines should not cross over each other. Color the auricles blue, ventricles red, coronary artery yellow, the other arteries orange and the vena cava (vein) purple. DORSAL VIEW= Use either a black colored pencil or black pen to outline and label the structures. Use either a black colored pencil or black pen and a ruler to draw lines from the labels to the structures. The lines should not cross over each other. Use the same colors you used in the ventral view. INTERNAL VIEW = Use either a black colored pencil or black pen to outline and label the structures. Use either a black colored pencil or black pen and a ruler to draw lines from the labels to the structures. The lines should not cross over each other. Color the auricles blue, ventricles red, valves yellow and arteries orange. 3). PAGE 2 – EXCRETORY AND RESPIRATORY STRUCTURES KIDNEY – INTERNAL VIEW = Use either a black colored pencil or black pen to outline and label the structures. Use either a black colored pencil or black pen and a ruler to draw lines from the labels to the structures. The lines should not cross over each other. Color the diagram (your choice). LARYNX / TRACHEA / LUNGS – VENTRAL VIEW = Use either a black colored pencil or black pen to outline and label the structures. Use either a black colored pencil or black pen and a ruler to draw lines from the labels to the structures. The lines should not cross over each other. Color the epiglottis, larynx and trachea one color. Color the lungs a different color (your choice). LUNG SECTION – INTERNAL VIEW = Use either a black colored pencil or black pen to outline and label the structures. Use either a black colored pencil or black pen and a ruler to draw lines from the labels to the structures. The lines should not cross over each other. Color the lung tissue red and the bronchioles blue. SALIVARY GLANDS - ORAL / BUCCAL CAVITY SALIVARY GLANDS ORAL / BUCCAL CAVITY UPPER LIP LOWER LIP HEART - VENTRAL / DORSAL / INTERNAL VIEWS VENTRAL VIEW DORSAL VIEW INTERNAL VIEW EXCRETORY AND RESPIRATORY STRUCTURES LARYNX / TRACHEA / LUNGS - VENTRAL VIEW KIDNEY - INTERNAL VIEW LUNG SECTION - INTERNAL VIEW