Purpose:
To study the internal anatomy of mammals.
Introduction:
In order to observe the levels of organization within an organism, you will
be completing a dissection. You will obtain a preserved double-injected
rabbit specimen. Double injected means that the arteries are filled with
red latex and the veins are filled with blue latex. You will be looking at
many different parts of the rabbit. Using the your textbook, my
instructions, and the diagrams completed in class you will be able to
located many of the structures on your own, but if you cannot find a
structure, please ask for assistance.
This is a learning experience so you may observe and discuss other
students' specimens.
Dissecting tools, including a scalpel, scissors, and forceps, will be used to
complete this dissection. Just because you are dissecting doesn't mean
that you can just cut up the specimen at your whim. You will need to
employ careful dissecting techniques to observe all the structures and
their connections to other structures. Be careful what you are cutting and
never cut more than is absolutely necessary to expose a structure.
Materials:
Preserved Rabbit
Dissecting Tray
Scalpel
Forceps
Scissors
Gloves
Goggles
Dissecting Pins
Procedures:
1. Place the rabbit in the dissecting tray with the abdominal cavity face up.
2. First examine the external anatomy of the rabbit. The rabbits body has
the same body cavities that humans do. Draw a diagram of rabbit labeling
the body cavities.
3. Next, you will skin the rabbit to expose the muscles below. This task is
best accomplished by making a small incision with your scalpel and then
using it to separate the connective tissues that connects the skin to the
first layer of muscles.
If you begin at the incision point where the latex was injected you will not
have to make the first cut.
4. Once you have the rabbit skinned, observe the muscles. Explain what
the muscles look like. What type of muscle are they?
Draw a diagram showing at least three muscles. Use your textbook to help
you label the three muscles you select.
5. Carefully tease away the muscles on one of the legs to expose the
bones. You should be able to see the tibia, fibula, femur, and patella.
Draw and label a diagram of these four bones as observed in the rabbit.
6. Notice the structure of the knee and the ankle. Explain the difference
between ligaments and tendons.
7. Next, you are going to cut into the ventral cavity. In order to do that,
make a small incision into the muscle in the middle of the abdominal
region using the scissors.
Then, cut in a straight line up and down to make a straight line through the
abdominal cavity from the throat down into the pelvic region. Be careful
not to cut too deep or you may damage the underlying organs.
8. Once you have an incision running the length of the abdominal cavity,
make a lateral cut on each side by the arms and legs to create two flaps of
muscle that open so you can see the internal organs.
Once you have the whole abdominal cavity open, draw a diagram and label
the internal organs. Be able to identify the following organs: liver, small
intestines, large intestines, diaphragm, stomach, spleen, heart, and lungs.
9. Notice the division between the thoracic cavity and the abdominal
cavity. What organ divides the abdominal and the thoracic cavities? What
is its function?
10. Next, locate and remove the liver by cutting the connective tissue near
the superior portion of the liver. On the underside of the liver locate the
gallbladder.
Draw a diagram of where the gallbladder is located on the liver. What is
the function of the liver and the gallbladder?
11. Once you have removed the liver you should be able to locate the
stomach, spleen, and the pancreas. The spleen is a thin curved organ
attached to the stomach that is usually reddish in color. The pancreas is
much harder to identify. The pancreas is a thin membrane that overlays
the stomach and spleen that looks like cottage cheese. What are the
functions of each of these organs?
12. Observe the intestines. How can you tell the difference between the
small and large intestine?
13. Remove the small and large intestines.
14. Once you remove the intestines, you should be able to see the
excretory system. Draw a diagram of the excretory system including the
kidneys, bladder, and ureters.
15. Remove one of the kidneys and cut it using coronal cut. You should be
able to see an intricate design of arteries and veins inside. Why are there
so many arteries and veins within the kidney?
16. Notice that the veins within the rabbit are dyed blue and the arteries
within the rabbit are dyed red. Why are veins and arteries dyed different
colors? What do those colors represent?
17. Next, locate the heart. Notice that it is enclosed within a sac called the
pericardium. What if the function of the pericardium?
18. Cut into the pericardium and remove it from around the heart.
19. Remove the heart from the body and cut it in half coronally to see the
artia and ventricles within the heart. Draw a diagram and label the artria
and ventricles.
20. Notice how the lungs have more than one lobe. Why do they have
more than one lobe?
21. If you follow the lungs up to the neck, you can observe the trachea and
the larynx. What is the function of each of these organs? Draw a diagram
of how the lungs, trachea, and larynx are located in comparison to one
another.
22. Run your finger along the length of the trachea. Notice the cartilage
rings that make it feel ribbed. Why do you think the trachea contains
cartilage rings?
23. Make sure you can identify all of the organs in the rabbit body.
25. When finished dissecting your rabbit, double bag it and dispose of it in
the body bag provided. Clean off your tools and dissecting trays and return
them to their proper place.