#8 - Ventral Body Cavity Organs

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#8 - Objectives: Use a cat dissection to study the organs of the ventral body cavity; Use virtual human dissection software and a human model to observe the organs of the Respiratory, Digestive,

1 #8 - Objectives: Use a cat dissection to study the organs of the ventral body cavity; Use virtual human dissection software and a human model to observe the organs of the Respiratory, Digestive, Urinary, and Reproductive systems. Equipment: Remember to bring gloves, goggles, dissecting kit, appropriate shoes, and photographic atlas. I. Virtual Human Dissection and Human Model Observation A. Preparation 1. Start the Anatomy & Physiology Revealed software by double clicking its icon. 2. Select the appropriate System (as indicated in the tables below) from the Module (top center) drop down menu. 3. On the home screen, click the dissection icon (top center, leftmost icon). 4. Using the directions on the following pages, find all of the structures on your lists. Use the human models to locate the structures you are viewing with the human dissection software. Within each system, there will be instructions that guide you in the removal of the organs from the human model. Remove organs only when instructed. Your instructor will sign off on the model before you leave the lab. After you have completed the lab, answer the questions in the laboratory report pages. Page1

1. lungs 2. trachea 3. diaphragm 4. larynx 4a. epiglottis Respiratory System Virtual Dissection 1. From the Module dropdown menu, chose the 11.Respiratory system. 3. Click the dissection icon (top center, leftmost icon).

5. From the Select structures group dropdown menu, click on lung, to view the structures. Remember that the pleural membranes cover the lung and line the thoracic cavity. 6.

2 1. lungs 2. trachea 3. diaphragm 4. larynx 4a. epiglottis Respiratory System Virtual Dissection 1. From the Module dropdown menu, chose the 11.Respiratory system. 3. Click the dissection icon (top center, leftmost icon). 2. Choose Lower respiratory from the Topic menu. 3. Using the sliders (bottom left), move to Layer 4 (slide Layers 1, 2, and 3 down). 4. From the Select structures type dropdown menu (below View, top left), choose Respiratory tract. 5. From the Select structures group dropdown menu, click on lung, to view the structures. Remember that the pleural membranes cover the lung and line the thoracic cavity. 6. Change the Select structures group to Trachea and bronchi to highlight the trachea (2) (APR Fig.1). 7. Observe the diaphgram (3) (APR Fig.1), a muscle used for breathing. 8. In the Topic menu, choose larynx, View, anterior. Identify the trachea (2), larynx (4) and epiglottis (4a) (RA Fig.2). 9. View the epiglottis (part of the larynx) in posterior, by using the sliders (bottom left), to move to Layer 4 (slide Layers 1, 2, and 3 down) and choose the posterior View (APR Fig.3). APR Fig.1 APR Fig. 2 APR Fig. 3 Page2

Respiratory System Human Model Organ Larynx Left lung Right lung Diaphragm Trachea Instructions Can be viewed without removing organs Remove the lungs first. Then, remove the thymus and heart.

3 Respiratory System Human Model Organ Larynx Left lung Right lung Diaphragm Trachea Instructions Can be viewed without removing organs Remove the lungs first. Then, remove the thymus and heart. Note: Epiglottis is not visible on the human model. Digestive System Virtual Dissection 5. greater omentum (part of the peritoneum) 6. liver 7. gallbladder 1. From the Module dropdown menu, chose the 12. Digestive system. 2. Click the dissection icon. 3. Choose Abdominal cavity from the Topic menu. Using the sliders (bottom left), move to Layer 2 (slide Layer 1 down). 4. From the Select structures type dropdown menu (below View, top left), choose Peritoneum. 5. Observe the greater omentum (5), liver (6), and gallbladder (7) (APR Fig.4). APR Fig.4 (Layer 2) Page3

Digestive System Virtual Dissection (cont.) 8. stomach 9. small intestine duodenum jejunum ileum Large intestine: 10. ascending colon 11. transverse colon 12. descending colon 13. sigmoid colon 14.

You can also highlight structures by clicking their name in the list. 7. Go through each Layer and identify the visible structures. 8.

9. Dissect further to Level 5 to view the spleen (14), pancreas (16), appendix (17), and the caecum (18) which is attached to the ascending colon (10).

4 Digestive System Virtual Dissection (cont.) 8. stomach 9. small intestine duodenum jejunum ileum Large intestine: 10. ascending colon 11. transverse colon 12. descending colon 13. sigmoid colon 14. spleen 15. mesentery (part of the peritoneum) 16. pancreas 17. appendix (vermiform) 18. caecum 19.esophagus 6. Click the button under each Layer label to see labeled pins on the dissection. You can also highlight structures by clicking their name in the list. 7. Go through each Layer and identify the visible structures. 8. In Layer 3, the stomach (8), small intestine (9), most of the parts of the large intestine (10, 11, 13), and the mesentery (15) are visible (APR Fig.5). The mesentery is also part of the peritoneum. 9. Dissect further to Level 5 to view the spleen (14), pancreas (16), appendix (17), and the caecum (18) which is attached to the ascending colon (10). Also view the descending (12) and sigmoid colon (13) (APR Fig. 6). 10. Type esophagus (19) into the search box. Choose Esophagus: Digestive: Dissection: Esophagus: Anterior. It is underneath the trachea and most easily viewed with the lungs removed. It leads to the stomach (8) (APR Fig. 7). APR Fig.5 (Layer 3) APR Fig.6 (Layer 5) APR Fig. 7 Page4

Digestive System Human Model Organ Liver Esophagus Stomach Instructions Can be viewed without removing organs Gallbladder Spleen Pancreas Duodenum Jejunum Ileum Ascending colon Transverse colon

5 Digestive System Human Model Organ Liver Esophagus Stomach Instructions Can be viewed without removing organs Gallbladder Spleen Pancreas Duodenum Jejunum Ileum Ascending colon Transverse colon Descending colon Caecum Remove the diaphragm, liver and stomach Can be viewed without removing organs Sigmoid Colon Appendix (vermiform) Remove the small and large intestines Notes: The mesentery cannot be seen on the human model. Urinary System Virtual Dissection 20. kidney 21. ureter 22. urinary bladder 23. urethra 1. From the Module dropdown menu, chose the 13. Urinary system. 2. Click the dissection icon. 3. Chose Upper urinary from the Topic menu. 4. Using the sliders (bottom left), move to Layer 4 (slide Layers 1-3 down). 5. View the kidneys (20). The ureters (21) and urinary bladder (22) (APR Fig. 8). 6. The urethra (23) is visible in the reproductive system (see below). APR Fig.8 (Layer 4) Organ Kidney (Left and Right) Ureter (Left and Right) Urinary System Human Model Instructions Remove pancreas and duodenum Page5

Reproductive System (Male) Virtual Dissection 23. urethra 24. scrotal sac (scrotum) 25. testis 26. vas (ductus) deferens 27. penis 28. epididymis 29. spermatic cord 1.

Click on the radio button under Layer 1 to see the labeling pins. 5. View the male structures shown in APR Fig. 9. Note that the testis (25) and epididymis (28) are enclosed within the scrotum (24).

6 Reproductive System (Male) Virtual Dissection 23. urethra 24. scrotal sac (scrotum) 25. testis 26. vas (ductus) deferens 27. penis 28. epididymis 29. spermatic cord 1. From the Module dropdown menu, choose the 14. Reproductive system. 2. Click the dissection icon. 3. From the Topic menu chose Pelvis - male. 4. Click on the radio button under Layer 1 to see the labeling pins. 5. View the male structures shown in APR Fig. 9. Note that the testis (25) and epididymis (28) are enclosed within the scrotum (24). 6. From the Topic menu, choose Testis and spermatic cord (isolated). Dissect down each Layer to view the vas deferens (26) and the spermatic cord (29) (APR Fig 10). A closer view of the testis (25) and epididymis (28) is also visible. Note that the spermatic cord contains the vas deferens and the testicular arteries and veins. APR Fig.9 APR Fig.10 Male Reproductive and Urinary Systems Human Model Organ Scrotum Penis Testis Epididymis Spermatic Cord Vas (ductus) Deferens Urinary Bladder Urethra Instructions Can be seen without removing organs Remove male reproductive organs NOTE: Before you proceed, insert the female reproductive organs into the human model. Page6

Reproductive System (Female) Virtual Dissection 30. vagina 31. uterus 32. ovary 1. From the Topic menu chose Pelvis - female. 2. Choose Sagittal, from the View menu. 3. Click on the radio button under Layer 1 to see the labeling pins.

View the uterus (31) and both ovaries (32) Note the position of the uterus superior to the urinary bladder (22) (APR Fig. 12). APR Fig.11 APR Fig.

7 Reproductive System (Female) Virtual Dissection 30. vagina 31. uterus 32. ovary 1. From the Topic menu chose Pelvis - female. 2. Choose Sagittal, from the View menu. 3. Click on the radio button under Layer 1 to see the labeling pins. 4. View the vagina (30), uterus (31), and ovary (32) (APR Fig. 11). 5. Choose Superior, from the View menu. 6. Click on the radio button under Layer 2 to see the labeling pins. 7. View the uterus (31) and both ovaries (32) Note the position of the uterus superior to the urinary bladder (22) (APR Fig. 12). APR Fig.11 APR Fig Female Reproductive and Urinary Systems Human Model Uterus Ovary Organ Vagina Urinary Bladder Urethra Instructions Can be seen without removing organs Remove female reproductive organs Before you proceed, replace the organs in the following sequence. When all of the organs have been replaced, have your instructor check the model and initial your lab report. Male Reproductive Organs Pancreas and Duodenum Small and Large Intestines Stomach Liver and Diaphragm Heart and Thymus Right and Left Lungs Page7

8 II. Cat Dissection A. Preparation 1. Wear goggles, gloves, and an apron for the entire time that you are working with preserved specimens. 2. Use scissors to cut open the bag and remove the cat, but do not let the preservative spill out of the bag. 3. Carefully dump the preservative into a special bin provided at certain lab sinks. DO NOT DUMP THE PRESERVATIVE DOWN THE SINK. 4. The plastic bag should then be thrown away in the regular trash containers. 5. Do not use a scalpel for dissecting. 6. For most of your work, use only your scissors and blunt probe. It is the safest and most efficient dissecting tool for muscles. 7. Use scissors only when specifically directed to do so in the dissection directions. B. The Respiratory System - CAT 1. Lungs 2. Trachea 3. Diaphragm 4. Larynx 4a. Epiglottis Lungs - Observe the lungs on either side of the heart. Note that like in humans, the left lung is smaller and has fewer lobes than the right lung. Trachea The trachea can be seen as a white tube at the midline of the neck leading to the lungs. Feel the hard cartilage rings in the trachea with your finger. Note that the trachea is still wide open because of the support provided by the cartilage rings. Diaphragm Observe the diaphragm at the base of the lungs. This large dome shaped muscle flattens to expand the thoracic cavity during inhalation. Note that it is skeletal muscle. Larynx Follow the trachea towards the head. The larynx can be observed as a widening of the cartilage in the neck and will appear shiny white. The largest cartilage visible is the thyroid cartilage. The larynx contains the vocal folds and epiglottis. Epiglottis Very carefully use your scissors to cut open the connective tissue at the very superior end of the larynx above the cartilage in a V shape. Use your finger or your blunt probe to lift up the flap-like epiglottis. This structure closes off the larynx during swallowing to prevent food from entering the airways. Page8

9 C. Digestive System CAT 5. Greater omentum 6. Liver 7. Gall bladder 8. Stomach 9. Small intestine (duodenum, jejunum, ileum) Large intestine: 10. Ascending colon 11. Transverse colon 12. Descending colon 13. Rectum 14. Spleen 15. Mesentery 16. Pancreas 17. Caecum (no appendix in the cat) 19. Esophagus Greater omentum The fatty lace-like structure covering the abdominal organs is the greater omentum. It is part of the peritoneum the serous membrane of the abdominopelvic cavity. Lift the greater omentum up and place it to the side to view the other organs. Do not detach it. Liver Observe the large red/brown liver in the right upper quadrant. Note that there are several lobes similar to humans. Gallbladder Between the lobes of the liver find the gallbladder. Sometimes a dark greenish stain is visible on the surface of the liver. The gallbladder itself is a sac-like structure with a green tint. In some animals you will have to spread the lobes of the liver apart to find the gallbladder. Stomach In the left upper quadrant, locate the stomach. You may need to move the greater omentum. It is a pinkish sac that varies in size. Find where the esophagus attaches to it close to the diaphragm. Use your scissors to cut open the stomach and observe the interior folds called rugae. Small Intestine The small intestine leads from the stomach. It coils around and is connected together by the mesentery. The first part of the small intestine is short called the duodenum. In the cat it continues to the first bend (flexure) and then it becomes the jejunum. This portion is the longest and leads to the ileum which empties into the caecum of the large intestine. Page9

10 Mesentery This thin membrane connects the small intestine coils. Note the many blood vessels running through it. It is part of the peritoneum. Large intestine (colon) The large intestine has a diameter of about twice the small intestine. Find where the ileum of the small intestine meets the caecum, a pouch at the beginning of the colon. Unlike the human, the cat has no appendix attaching to the caecum. Follow the colon up (the ascending colon) to the very short transverse colon (basically a turn) and down the descending colon to the rectum. Most of the cat s rectum is not visible without further dissection. The anal opening is visible from the exterior. Spleen The spleen is a reddish-brown structure visible behind the left side of the stomach. Pancreas The pancreas is best visible under the stomach by lifting the greater omentum and placing it up over the stomach. At the juncture where the omentum attaches to the stomach you can see a very delicate lobular material sometimes pinkish-white embedded in the connective tissue. The pancreas runs horizontally across the abdomen and may continue down the duodenum of the small intestine. Esophagus In the thoracic cavity, find the esophagus by gently moving the trachea aside to the cat s right. It is a soft brown/pink flattened tube directly underneath the trachea. Follow it down to the stomach. D. Urinary System CAT 20. kidney 21. ureter 22. urinary bladder 23. urethra Kidney The kidneys are located on either side of the abdomen behind the other organs. They are behind the peritoneum and so are called, retroperitoneal. You will need to remove this layer to see the kidneys. Be careful not to damage the ureters as you do so. Remove one of the kidneys and use your scalpel to slice it open using a frontal section. Observe the outer cortex and inner medulla note differences in color and texture. Ureter From the medial surface of each kidney a ureter attaches. These delicate flattened tubes carry urine produced in the kidneys down to the urinary bladder for storage. Urinary bladder The urinary bladder is found in the pelvic cavity as a rounded sac. The ureters attach to the posterior wall of the bladder and the urethra lies inferior to it. Page10

11 Urethra The urethra is visible by lifting the bladder slightly and cleaning away the connective tissue at the base of the bladder. Observe the tubular urethra which carries urine from the bladder to the outside of the body. E. Male Reproductive System - CAT 24. scrotal sac (scrotum) 25. testis (testes pl.) 26. vas (ductus) deferens 27. penis 28. epididymis 29. spermatic cord Scrotal sac (scrotum) The scrotum is the skin covering the testicles (testes). The skin with fur will need to be removed to view the testes. If your male cat has been castrated, it will have no scrotum or testes. Testis (testes pl.) Two testes can be seen once the fur is removed. To view the testis better, as well as the epididymis, the capsule around the testes should be removed using scissors. Epididymis The epididymis is a coiled tube located along the posterior surface of each testis. It collects and helps mature sperm produced in the testes and passes them to the vas deferens. Vas (ductus) deferens The vas deferens is a tube leading from the epididymis through the spermatic cord and loops behind the urinary bladder to fuse with the urethra at the prostate. In the cat with the pelvis intact, it is most easily viewed within the spermatic cord near the testes. Spermatic cord This structure encompasses the vas deferens, testicular arteries, veins and nerves from each testis. It passes through the inguinal canal to the abdominal cavity. Penis The penis of the cat is visible externally, located between and slightly above the testes. To view the structures more closely you can remove the fur covered skin using scissors. F. Female Reproductive System -CAT 30. Vagina (viewed as the urogenital sinus) 31. Uterus 32. Ovary Vagina In the cat the urethra and the vagina open into a common orifice called the urogenital sinus. It is located ventral to the anal opening. Page11

12 Uterus The cat uterus has two horns which are extensions going up the lateral abdominal wall each attaching to an ovary. Each long uterine horn allows space for many offspring to grow. The cat uterus lacks the long uterine (Fallopian) tubes seen in the human. The thickness and color of the uterine horns varies according to whether the cat has had / does have a pregnancy. The uterine horns can vary from very thin and pinkish, similar in appearance to the ureters, or very thick. A pregnant cat will have an enlarged uterus with large blood vessels. Ovary At the end of each uterine horn, a small flattened lobular ovary is attached. It may appear whitish, yellowish, or pinkish in color and often resembles a very small bean. G. Directions for Putting Your Cat Away and Cleaning Up 1. All loose cat parts should be thrown away in the appropriate container as indicated by your instructor. Please do NOT allow cat parts to end up in the sink. They will clog the drain and cause extra work for lab assistants. 2. Place the cat into the container provided for disposal as directed by your instructor. 3. Thoroughly wash your dissecting tray with soap and water, dry, and return it to the lab bench where you found it. 4. Use the spray disinfectant cleaner provided to thoroughly wipe down your lab bench area so that it will be ready for the next group of students. 5. Dispose of your gloves, paper towels and old plastic bags in the regular trash containers as directed by your instructor. 6. Make sure that you take your dissecting kit and goggles with you when you leave the lab. Page12

13 Name: Laboratory # 8 Report I. Cat and Human Dissection 1. Label the human and cat organs indicated on the next page. Note that some organs are visible on only one or both of the specimens. Page13

14 Name: 1. Diagram labels: A. B. C. D. E. F. G. H. 2. Name the two parts of the peritoneum that a.) we observed in the human and cat: b.) 3. What part of the respiratory system contains the vocal folds? 4. Name the three parts of the small intestine: a) b) c) 5. Name the tubes which take urine from the kidneys to the urinary bladder. 6. What tube eliminates urine from the body? 7. What four structures are in the spermatic cord? a) b) c) d) II. Human Model 8. Examine the kidneys on both sides. Which kidney is lower? Suggest a possible reason for this difference in kidney location. Page14

human model. J I H G K 11. Identify the digestive structures indicated on the diagram below.

15 Name: 9. Place the following in order from superior to inferior: transverse colon, liver, diaphragm. A. B. C. 10. Since most of this organ lies behind the stomach, the can only be observed clearly after the stomach is removed from the human model. J I H G K 11. Identify the digestive structures indicated on the diagram below. Then draw in and label: spleen, liver, gall bladder A. L A B. C. D. B E. F. C G. H. I. J. D K. F E L. 12. Identify the urinary system structures Page15

Name: Identify structures indicated for the respiratory, male, and female reproductive systems. Respiratory System 1. 2. 3. 4. 5. 6. 7.

16 Name: Identify structures indicated for the respiratory, male, and female reproductive systems. Respiratory System Male Reproductive System Female Reproductive System Page16

DISSECTION 8: URINARY AND REPRODUCTIVE SYSTEMS

8546d_c01_1-42 6/25/02 4:32 PM Page 38 mac48 Mac 48: 420_kec: 38 Cat Dissection DISSECTION 8: URINARY AND REPRODUCTIVE SYSTEMS Typically, the urinary and reproductive systems are studied together, because