Cat Dissection
Guide and Question Packet
Human Anatomy & Physiology
Isidore Newman School
Dissection team:
Approach/Purpose
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You will work in pairs throughout this process. Your principle objective in this
dissection is to expose the cat organs for study, not to simply cut up the
animal. You will be asked to make comparisons between that which you
observe about the cat’s anatomy and human anatomy. Please remember: We
respect the cat as a once-living organism. Anyone who is incapable of
such respect will be dismissed from the project entirely.
Introduction
You will utilize “The Taxonomy & Physiology of the Cat” dissection guide found at
your lab table.
In this guide, please go to page 6 and read the section Why study the cat?
Next, review Figures 2 and 3 found on pages 2 and 3.
1. Instead of using anterior and posterior in describing directions on
quadrupedal organisms, what other terms are often used?
2. If one starts at the abdomen and moves in the superior direction on a human,
one ends at the head. If one starts at the abdomen and moves in the superior
direction on a cat, one ends up where?
External Features
Next, go to pages 7 and 8 and read External features. Use these pages to help
you examine the external features of the cat.
3. What is the nictitating membrane? Try to examine it if possible.
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4. What are vibrissae?
5. Please explain the distinct difference between the way in which cats walk
versus the way in which humans walk.
6. In simplistic terms, what are the:
a. nares
b. rhinarium
c. auricle
d. manus
e. tori
f. pes
Next, please read the section Gender differences on page 8. Use this
information to help you assess the sex of your cat.
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7. Based on your assessment of your cat, what sex do you determine your cat to
be? What evidence led you to this conclusion?
Muscular System
Now go to page 15 in your guide and examine Figure 13 – The muscular system.
Please acquire several label pins and, using this diagram, label the following
muscles on your cat by inserting the pins directly into its musculature. When
complete, please call over your instructor for label placement verification.
1. clavotrapezius
2. acromiotrapezius
3. spinotrapezius
4. latissimus dorsi
5. gluteus maximus
6. gastrocnemius
7. biceps femoris (part of hamstring group)
8. sartorius
9. external obliques
10. triceps brachii
The Dissection
Now you are ready to begin an examination of the internal anatomy of your cat.
Please go to the bottom of page 8 and begin reading the section The
Dissection. On page 9, please read and follow instructions 1 through 13.
However, please ignore step #14 for now and do not remove any organs just
yet.
Abdominal cavity
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Refer to pages 17-20 of your guide for assistance with this portion of the
dissection.
There may be whitish membranes (the greater omentum) covering the organs of
the abdominal cavity. If so, remove this membrane using forceps. Try to remove
it in one piece, if possible.
Find and identify the following organs of the abdominal cavity:
1. diaphragm
2. liver
3. stomach
4. spleen
5. pancreas
6. small intestine
7. large intestine
Now, carefully remove the liver intact. Be gentle. Once removed, flip the liver
over and search for the gall bladder. The gall bladder is found under the liver
and between its lobes.
8. How many lobes does your cat’s liver possess?
9. Describe the appearance and “feel” of the gall bladder.
10. What are some of the functions for these 2 previous organs in humans?
Now, you should remove the stomach. However, bring with it a short portion of
the esophagus to ensure the cardiac sphincter comes with it. Also, bring with it
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enough of the small intestine to ensure the pyloric sphincter AND pancreas
comes with your stomach as well. Be careful: The pancreas is fragile!
11. Describe the appearance of the pancreas.
12. What are some of the functions of the pancreas in humans?
Take note of the hard sphincters at the beginning and end of the stomach. What
are these? What purposes do they serve?
Now cut open the stomach along its outer arc, exposing its inner contents.
13. What did you find inside the cat’s stomach, if anything?
14. Please describe the appearance of the inside wall of the stomach. Relate
this appearance to the stomach’s function.
Now carefully remove the cat’s spleen.
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15. Describe its appearance.
16. In humans, the spleen is considered to be an organ belonging to which body
system? How does the shape and size of the cat spleen differ from that which
you can find about a human spleen?
Now, remove the small intestines and large intestine in one large mass of tubing.
Try to cut the large intestine as close to the anus as possible. Be careful! You
do not want to damage any parts of the urogenital system in the pelvic
cavity!
Upon removing the small and large intestines, lay them out as best as possible
on a paper towel and attempt to measure each.
Length of small intestine = ____________________
Length of large intestine = ____________________
17. How do the functions of these 2 tubes differ? Please explain.
Thoracic Cavity
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Refer to page 19 of your guide for assistance with this portion of the dissection.
Additionally, utilize The respiratory system section on pages 25-26 and The
circulatory system section on pages 26-29.
Find and identify the following organs of the thoracic cavity:
1. trachea
2. larynx
3. thyroid glands
4. esophagus
5. thymus gland
6. heart
7. lungs
Now, carefully remove one entire lung.
18. Describe the lung tissue in general. Appearance? Texture? Elasticity?
Remove a sizable lobe from your excised lung. Obtain a large beaker and fill it
with water. Place the lung lobe in the water and take note.
19. What did you observe with your lung tissue when it was placed in water?
(Fresh, unpreserved lung tissue will usually float.) Explain.
Next, try to excise as much of the trachea as possible. Be certain to bring the
larynx (voice box) with it. Additionally, if you look on the superior side of the
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trachea (remember the cat is quadrupedal) you will find the esophagus. This is
yet another tube attached to and running along the superior side of the trachea.
Try to remove the esophagus with the trachea at the same time if you can. Be
careful! The esophagus is soft and fragile!
20. Notice the rings of cartilage that make up the walls of the trachea. Why do
you suppose that cartilage is used in the walls of the trachea, but not in the walls
of other tubes like the esophagus?
21. Describe the differences between the esophagus and the trachea, both in
terms of anatomy and physiology.
Try to identify the thymus gland resting on top of the heart.
22. What is the thymus gland responsible for in humans?
Now, carefully remove the heart. As you do so, try to bring several branches of
those blood vessels coming into (veins) and departing from (arteries) the heart.
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This may prove a bit challenging as these vessels, now colored blue and red, are
filled with a rubbery latex material.
See if you can identify several of these larger blood vessels. “Red” vessels
indicate oxygen-rich blood flow and “blue” vessels indicate oxygen-poor blood
flow.
With a dissecting needle, “pluck” at the very thin membrane tightly clinging to the
surface of the heart. This is the pericardial membrane.
Now, cut your heart open. Try your best to identify the “front” of your heart
(ventral side in the cat). Cut the heart in half, making a frontal section, allowing
you to view all 4 chambers as you typically see it illustrated in textbooks.
23. You were asked to take note of the thin pericardial membrane that encloses
the heart. What is this membrane’s role in assuring the heart operates
efficiently?
24. When you removed the heart, you were instructed to leave a significant
portion of each vessel still attached to the heart. Upon observing these vessels,
which vessels appear to be the largest? What color are they?
25. How many total vessels can you count entering or leaving the heart?
26. Upon cutting the heart open, what color is the left side of the heart (the cat’s
left, that is)? The right side (the cat’s right, that is)? Does this representation
correspond with that which you know about blood flow through the heart?
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Lower abdominal/pelvic cavities
Refer to pages 21-25 of the dissection manual for assistance with this portion of
the dissection.
Locate the kidneys embedded in the wall of the cat’s back. If you are having
trouble viewing them, carefully remove some of the connective tissues covering
them. Be careful! You do not want to destroy any surrounding tissues.
On the medial side of one of the kidneys, locate a very thin, fine, white tube. This
is a ureter. Trace the ureter from the medial side of the kidney posteriorly all the
way to the urinary bladder.
27. Describe the appearance and “feel” of the urinary bladder.
Now, using care and patience, remove one of the kidneys from the body wall of
the cat. If possible, bring some blood vessels and the ureter with it.
Cut the kidney in half, making a frontal cut and cutting along the outer arc of the
kidney. This will allow you to view the internal make up of the kidney.
28. Describe the internal appearance of the kidney.
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29. What is the function of the kidney?
On the kidney that is still intact and still embedded, try to identify an adrenal
gland.
30. What is the function or purpose of the adrenal glands?