Download Fetal Pig Dissection HB

Name: _______________________
Score: ___________
Organ Systems and Organs Exploration
Using a Fetal Pig
As members of the class Mammalia, pigs exhibit the two chief mammalian
characteristics that set all mammals apart from the other classes. The two
characteristics are:
1. skin covered with hair or fur
2. mammary glands (milk producing glands) in the female to nourish the
young
Humans and pigs are placental mammals. This means their embryos develop within
a uterus (womb) and are nourished via a placenta. The placenta is formed partly
from the inner lining of the uterus and partly from the developing tissues of the
embryo. During gestation, there is an exchange of substances between the blood
of the mother and embryo across the placenta through the umbilical cord. The
fetal pig you are going to dissect in an unborn animal, therefore a portion of the
umbilical cord is present on your specimen.
The specimen you will dissect was obtained from a pregnant sow (mature female
swine) in the process of being slaughtered at an "abattoir" or slaughterhouse.
These fetuses are then made available for biological study. There are usually
seven to twelve young in a single litter.
Sus scrofa (the pig) is omnivorous like humans, feeding on both plant and animal
matter. The body temperature of the adult pig is slightly higher than that of the
human. The life span of the pig is 15 - 20 years. The life span of humans averages
75 - 80 years. The pig is a quadruped and the human is a biped. This means that
the pig uses four legs to walk while human uses two legs. The pig walks on his/her
toes which is called digitigrade locomotion. Man walks on the sole of the foot.
This is called plantigrade locomotion.
All multicellular organisms are made out of many layers. The layers are
represented in the picture below. The important thing to understand is that each
layer is used to build the next layer.
For example: the smallest level, called subatomic particles, are used to build
atoms. Atoms are then used to build molecules, molecules are used to make
macromolecules (aka. Organic molecules), macromolecules are used to make
organelles, organelles are used to make cells, etc…
Smallest level
Largest Level
The fetal pig is an organism whose anatomy is very similar to human beings. The
fetal pig is comprised of the same 11 organ systems as humans.
Complete the matching task below. Use the simple sentence to help you remember
the 11 organ systems.
C
DR
SMILE
RUN
1. Nervous System ____
a. involved with making children
2. Integumentary System ____
3. Respiratory System ____
b. system where food is broken
down and nutrients are
absorbed
4. Digestive System ____
c. external and internal barrier
5. Excretory System ____
d. excretes (removes) waste
from blood stream
6. Skeletal System ____
7. Muscular System ____
8. Circulatory System ____
9. Endocrine System ____
e. fights off disease
f. made of a group of organs
that make chemicals to slowly
regulate body
10.Reproductive System ____
g. communication system in the
body (relays fast messages)
11.Lymphatic System ____
h. helps body move its structure
i. provides structure for the
body
j. brings nutrients, oxygen and
other important chemicals
throughout the body
k. brings oxygen and carbon
dioxide in and out of body
This web address, http://www.youtube.com/user/LakelandBiology, has videos of
the internal dissection of the pig. You may wrap your smart phone in plastic wrap
(saran wrap), and access the site to help you through the dissection, as well as to
help you review for the test.
Purpose: To explore the various organ systems and organs in a fetal pig. While
going through your dissection you will describe and capture pictures of the various
structures you will observe.
Materials: scalpel, scissors, dissecting tray, fetal pig, string, tape, camera, plastic
ruler, pen/pencil and paper, and possibly saran wrap for your smart phone
Procedures: Fetal Pig Dissection: External Anatomy
Sexing your pig:
1. Determine the sex of your pig by looking for the opening to the urethra (tube that
releases urine from the body). On females, this opening is located near the anus. On
males, the opening is located near the umbilical cord.
If your pig is female, you should also note that the opening is covered with a flap called
the urigenital papilla, which is present near the genital opening. Males do not have this
papilla.
1. Both males and females have rows of nipples, and the umbilical cord will be present in
both. Locate both of them.
2. What is the sex of the pig? __________________
3. Gestation (development in the womb) for the fetal pig is 112-115 days. The length of the
fetal pig can give you a rough estimate of its age. Some are in MILLIMETERS, and some
are in CENTIMETERS
4. 11 mm - 21 days
17 mm - 35 days
2.8 cm - 49 days
4 cm - 56 days
22 cm - 100 days
30 cm – birth
5. How old is your pig (estimate based on the range)? _______________
**Clean the plastic ruler after you use it to measure the length of the pig.
Opening the pig’s mouth:
1. To open the mouth take your scissors and cut straight back on the corners of the mouth
pushing through the jaw bone. The mouth should hinge back.
a. Open the pigs mouth and locate the hard and soft palate on the roof of the mouth. Can
you feel your own hard and soft palates with your tongue?
2. Continue cutting the sides of the mouth backwards until your incision is underneath the
eye of the pig. The epiglottis, a cone-shaped structure at the back of the mouth should
be exposed.
The epiglottis is a flap of skin that will close the opening to the esophagus (swallowing) or
the trachea (breathing).
Integumentary & Muscular System
1. Using your scissors and your scalpel remove the skin from around the body of the fetal
pig. Examine how the skin is connected to the muscles. Record all observations and take
pictures along the way.
2. Once the skin is removed tweeze through the muscles to visualize how they are organized
and attached to the bones. Record all observations and take pictures along the way.
Fetal Pig Dissection: Internal Anatomy
In this activity, you will explore the internal make up of the fetal pig. Remember, that to
dissect means to "expose to view" - a careful dissection will make it easier for you to find the
organs and structures. Be sure to follow all directions.
The Incision
1. Place your fetal pig in the dissecting pan
belly up.
2. Use string to "hog-tie" your pig so that
the legs are spread eagle and not in your
way.
3. Use scissors to cut through the skin,
muscles and bone according to the
diagram to the right. Do not remove the
umbilical cord.
4. After your cuts are done, now cut
through umbilical cord.
Once the fetal pig’s organs are exposed locate as many organs as you can without removing
them. Once you get to a point where you have identified as many organs as possible,
choose one of the following organ systems to remove; Digestive system or Respiratory
system. Try to remove the organ system intact. You may carefully remove other organs in
order to access the organ system, but take pictures of all organs after removing them. As
you remove organs place them in the dissecting tray. Record all observations and take
pictures along the way.
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Diaphragm
Liver
Gall bladder
Stomach
Spleen
Pancreas
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Kidneys
Bladder
Heart
Lungs
Trachea
Esophagus
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Small intestines
Colon (large intestines)
Epiglottis
Ureters
Bronchial Tubes
Post Lab Questions: After dissecting the fetal pig, answer the following questions below.
Answer in complete sentences using evidence from your observations for full credit.
1. What was the largest internal organ that you observed? _______________________
2. Pigs eat almost any kind of food, including dead insects, worms, trees, bark, garbage and
even other dead pigs. Based on one of the major function of the liver, why would the pig
need such a large liver? Explain.
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3. What color was the spleen (flap-like organ over the stomach)? Based on its function, why
would you expect it to be this color? Explain.
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4. All of the stomachs of the pigs were empty. Why wouldn’t any of them be full? (hint:
where does the fetal pig get its food from?)
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5. Like human fetuses, the lungs of the fetal pig were not fully developed. Why are lungs
one of the last organs to develop in fetuses, and where do they get their oxygen from
while in the womb? Explain.
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6. The heart of the fetal pig was very large. In humans, the heart starts beating 22 days
into the 9 month pregnancy. Why does the heart start pumping blood to all the cells so
early in pig/human development? Explain.
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7. If you stretched a pig’s or human’s intestines out from end to end, they could be twenty
or more feet long. Based on their function, why do they need to be so long? Explain.
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8. Anatomy is the study of the structure of organs, while physiology is the study of the function of
organs. Why is it important to study anatomy and physiology together? (Hint: The Wright
brothers invented the first flying planes, and they spent a lot of time studying the shapes of
birds’ wings.)
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9. Relating to question 8, the structure of an organ helps it do its job. Describe ways in which the
human’s and another organism’s (snake, rabbit, etc) anatomy are different, and why the features
you describe help each organism survive in the environment in which it lives.