Fetal Pig vs. Human Being
Introduction:
Before the project commences, it must be noted that the pig was still in its developing
stages, but with enough differentiated cells that will allow for anatomical analysis. This fact
accounts for the absence of some organs. Because of this, students may not be able to perform a
complete autopsy of the specimen. Also, because pigs and humans belong in the same class,
Mammalia, their internal structures are mostly the same, with some small differences. These
differences may play key roles in the different metabolic processes of pigs and humans, which is
the main focus of this experiment. Analyzing these differences may provide an insight as to how
these organisms that belonged to the same class diverged into different species, with pigs
belonging in the order Artiodactyla and the humans belonging in the order Primate. The key
concept in this experiment is evolution. Evolution is the gradual change of organisms over time
in response to slowly changing environments. It can be summarized into natural selection and
descent with modification. How do pig organs and human organs compare? The goal of this lab
is to create a comparison between the anatomies of a fetal pig (Sus scrofa) and a human being
(Homo sapiens). The project consists of the dissection of a fetal pig and the excision of the brain,
heart, lungs, diaphragm, tongue, liver, stomach, small intestine, large intestine, kidneys. These
organs will be compared to human organ counterparts in mass and structure. This comparison
may allow for explanations on how the organisms evolved over time, in conjunction with the
changes in the respective genotypes of pigs and humans. This experiment demonstrates that
evolution unites all of the themes of biology.
Materials:
Fetal Pig Dissection
 Preserved fetal pig
 Dissecting pan
 Probe
 Twine
 Scissors
 Single-edged razor blade
 Scalpel
 Water
 Forceps
 Paper towels
 Textbook
 Dissecting pins
 Fetal Pig Diagram
Human Comparison
 Human Diagram
 Masses of Major Organs
 Procedures:
A. Fetal Pig Dissection
i. External Anatomy
a. Obtain a fetal pig, rinse with water, and place on a dissecting pan.
b. Identify the head, neck, thorax, abdomen, forelimbs, hindlimbs, and tail.
c. Examine the head, noting the presence of upper and lower lids. Locate the snout. Locate
the mouth and gently open it.
d. Compare the forelimbs to the hindlimbs (note number of digits).
e. Locate the umbilical cord. List observations.
ii. Internal Anatomy
a. Place the pig on the dissecting pan with its ventral side facing up.
b. Tie one end of a length of twine to the ankle of a forelimb of the pig. Do the same to the
other forelimb and the two hindlimbs.
c. Make an incision as directed by Figure 34-1. (See Lab Packet)
I. Digestive System
a. Locate the peritoneum, the reddish-brown liver, the gall bladder, the bile duct, the
light-colored stomach, the esophagus, the small intestine, the large intestine, the
spleen, and the pancreas.
b. Using scissors, remove the liver, stomach, and intestines. Separate the small and
the large intestine. Weigh each organ.
II. Thoracic Cavity
a. Find the diaphragm muscle and carefully clip the edges using scissors.
b. Excise the tongue, the diaphragm, and the lungs. Acquire the mass of each organ.
III. Circulatory System
a. Carefully remove the pericardium and observe the heart. Locate the heart, the
umbilical artery, the umbilical vein, the left and right atria, the left and right
ventricle, the anterior and posterior venae cavae, the dorsal aorta, the pulmonary
arteries, the pulmonary veins, and the coronary arteries veins.
b. Using the dissecting scissors, cut the blood vessels attached to the heart, and
remove the heart. Weigh the organ.
IV. Excretory System
a. Locate the bean-shaped kidneys. Use the forceps to scrape away any fat. Examine
the ureters, which leave the concave side of each kidney. Trace the oath of the
ureters from both kidneys to the urinary bladder.
b. To observe the urethra, first pull the hind legs apart. Then, using the scissors, make
a small anterior incision a little to the side of the midventral line.
c. Excise the kidneys. Weigh each organ.
V. Male Reproductive System
a. Locate the scrotal sacs at the male pig’s posterior end. Cut one sac open, and
determine is a testis is present. If a testis is not present in the scrotal sac, locate it
in the tubelike inguinal canal.
b. Observe a testis. Locate the epididymis and trace the pathway as it passes through
the inguinal canal, which is called the vas deferens.
c. Locate the urogenital duct, the part of the epididymis that forms loops over the
ureters and leads into the urethra. Locate the sheath of tissue covering the penis.
Find the urogenital opening, which is posterior to the umbilical cord.
VI. Nervous System
a. Remove the skin covering the skull of the fetal pig.
b. Carefully slice the skull of the pig and remove the soft skull.
c. Observe the brain. Cut the spinal cord that connects to the brain. Remove the brain.
Weigh the organ.
B. Comparison with the Human Anatomy
a. Identify the organs that will be used for the comparison. (Brain, Heart, Lungs,
Diaphragm, Tongue, Liver, Stomach, Small Intestine, Large Intestine, and
Kidneys)
b. Use different sources to list observations of the different organs.
c. Acquire the masses of the organs from outside sources.
Data:
Organ
Function
Fetal Pig
Location
Brain
It is the control
center of the
organism.
Head/Skull
Heart
It pumps blood
through pig,
distributing
oxygenated blood.
It is the medium
for gas exchange.
It controls the
contraction and
relaxation of the
lungs.
It senses the
flavor of the food
and sends signals
to the brain for
proper digestive
responses.
It filters the blood
Thoracic Cavity
Lungs
Diaphragm
Tongue
Liver
Thoracic Cavity
Thoracic Cavity
Head/Mouth
Description
It is noodle-like,
fleshy (light tan) –
colored, soft and
squishy.
It is an acornshaped, reddish
gray organ.
Mass (g)
~7.4
~3.9
It is brown, grey
~11.7
and firm.
The organ is small, ~0.4
translucent and
thin.
It is light tan and
firm.
Abdominal Cavity The liver is a
~3.8
~18.8
of toxins.
Stomach
Small Intestine
Large Intestine
Kidneys
Organ
It breaks down
food and absorbs
nutrients.
It continues the
nutrient
absorption began
by the stomach.
It removes the
water from the
organic material.
It also absorbs the
remaining
nutrients in the
food.
They remove
wastes from the
blood through
osmosis.
large, dome-like,
grey colored, fivelobed organ.
Abdominal Cavity It is bean-shaped
and light tan.
~6.2
Abdominal Cavity It is light tan,
noodle-like and
long.
~5.8
Abdominal Cavity It is dark brown,
noodle-like and
long.
~4.7
Abdominal Cavity They are brown
and bean-shaped.
~5.8
Human Anatomy (Average Mass for Male Chile Under the Age of 11)
Function
Location
Description
Mass (g)
Brain
It coordinates the
movements and
processes of the
whole body.
Head/Skull
Heart
It pumps
oxygenated blood
throughout the
body.
Thoracic cavity
Lungs
They acquire the
Thoracic Cavity
oxygen transported
by the blood to the
various organ
systems.
It is an organ
~1098.24
composed of five
distinct regions:
cerebrum,
diencephalon,
midbrain, pons
(cerebellum), and
the medulla
oblongata.
It is divided into
~88.17
the right atrium
and ventricle and
the left atrium and
ventricle by the
septum.
It is a moist, multi- ~287.94
lobed organ with
many infoldings to
enhance the
surface area of gas
exchange.
Diaphragm
Tongue
It controls the
contraction and the
relaxation of the
lungs during
breathing.
It determines the
taste of the food. It
then sends signals
to the brain, which
determines an
appropriate
response.
It filters the blood
of toxins.
Thoracic Cavity
It is a flat muscular ~1600
sheet.
Head/Mouth
It is a reddish
organ made
completely out of
muscle.
Abdominopelvic
Cavity
It is a reddish
brown, beanshaped, organ,
slightly large, and
composed of four
lobes.
An elastic organ
with many
infoldings to
enhance the
absorption of
nutrients. It is also
capable of
contracting in
order to increase
the efficiency of
digestion.
This is the longest
compartment of
the alimentary
canal (6m long)
and has a small
diameter.
This is composed
of three parts:
colon, cecum, and
rectum. It has a
larger diameter
than the small
intestine.
They are red,
bean-shaped
organs.
Liver
Stomach
It continues the
Abdominopelvic
digestion process, Cavity
breaking down the
food further for the
extraction of
nutrients in the
small intestine.
Small Intestine
It extracts nutrients
through the use of
bile salts, pepsin,
amylase, and other
hydrolytic
enzymes.
It removes the
water and
additional
nutrients from the
organic matter.
Abdominopelvic
Cavity
It filters the blood
of waste materials.
Abdominopelvic
Cavity
Large Intestine
Kidneys
Abdominopelvic
Cavity
~70
~619.73
~3.69
Unknown
~1814.36
~108.92
Data Analysis:
Through the experiment, we measured the mass of the organs within the fetal pig and
compared them with the average mass of the organs within a human being that is under the age
of 11. The masses, as expected, were proportional to one another, with human organs having
significantly larger mass than pig organs. Despite these differences, human and pig organs have
similar structures and functions and both serve the same purpose of coordinating the movements
within the bodies of the two organisms. This shows that even though the two organisms are of
different species, they both have similar internal structures. Being in the fetal stage, the organs of
the pig are not fully developed. These organs may have the same mass as human organs once
they reach full maturation. There are major differences between some organ structures of the pig
and a human being. A pig consumes food from a variety of places, often from unknown sources.
Because of this fact, pigs have evolved to have body mechanisms that allow them to be protected
from poisonous substances. The liver of a pig consists of five lobes: the right lateral, the right
central, the left lateral, the left central, and the caudate. On the other hand, a human liver is
composed of only four lobes. The five lobes of the pig liver detoxify blood more thoroughly than
human liver, which is necessary since pigs are not knowledgeable about the contents of the food
they consume. This ensures that the pig is protected from substances that may cause damage to
its other organs or slow down metabolic activities. The intestines of a pig and a human being are
also different in structure. A pig’s intestine is spiral, whereas a human’s is linear. The spiral
orientation of the pig’s intestines allow for a longer duration of nutrient absorption, allowing for
the extraction of more nutrients. Not only does the duration increase, but the surface area of the
absorbing medium greatly increases as well. This efficiency in absorption is necessary because
of the nature of a pig’s meals. Nutrients can be found embedded sometimes in the most unusual
of places, requiring thorough absorption. These nutrients are also necessary in keeping the
metabolism of the pig constant, maintaining homeostasis as a result thereof. Domesticated pigs,
and even wild ones, acquire their nutrition from anywhere and anything. Because of this
behavior, an increased thoroughness in detoxification of blood and increased efficiency in
nutrient absorption have become essential evolutionary adaptations.
Conclusion:
The purpose of this experiment is to determine whether or not there is significance in the
different masses of the organs of a pig and a human being. A fetal pig was dissected in this
experiment, with major organs excised, which included the brain, heart, lungs, diaphragm,
tongue, liver, stomach, small and large intestine, and the liver. These organs were compared with
human organs in both the qualitative and quantitative categories. Organs from both organisms
exhibited similar physical characteristics. There was a significant difference in the masses, but it
is mostly due to the underdevelopment of the organs. The fetal pig was only one hundred days
old, so not all of the cells have differentiated into different tissues and organs, which would have
been achieved in approximately one hundred twelve to one hundred fifteen days. Even then,
these organs will continue to grow as the pig acquires nutrition. Cell division would continue
without much damage to the DNA as long as the telomeres are intact. Major evolutionary
adaptations have occurred in some of the organs of the pig that allow for survival in challenging
environments. Some of these adaptations, such as the ones discussed in this experiment, deal
with the tolerance of pigs to the most unorthodox of meals. Pigs have specialized organs that can
detoxify the blood more thoroughly than a human liver can and colon orientation that allows for
a more efficient nutrient absorption than a human colon. These findings account for the use of
pig organs during surgical procedures. Sometimes, the blood of a human being is passed through
a pig liver for thorough detoxification, removing foreign and often pathogenic particles. This
would ensure that the blood is rid of dangerous substances after the surgical procedure, keeping
any replaced organs safe from corruption. The experiment was a success and the question was
answered, as the mass and the structure of the pig organs were identified and compared to organs
in a human system. More research regarding other evolutionary adaptations will allow for a more
thorough comparison between a human and a pig. It would demonstrate the diversion of the two
organisms from the class Mammalia. Patience and caution during the dissection would have
improved the results of the experiment. Some of the organs were excised in the wrong places,
often causing their fragmentation. For example, the brain was damaged in approximately three
pieces. The lungs were cut in multiple pieces. Also, a large portion of the liver was excised, but a
few remnants of the organ were left in the pig, signifying an error in the dissection. Organ
structures in different organisms differ from one another because of the different environments
each occupies. Organisms face different challenges that require specific evolutionary
adaptations. This is referred to natural selection. Natural selection accounts largely for the large
variation of organisms in the whole biosphere. Because of this, evolution truly unites all the
themes of biology.
Work Cited
1. Campbell, Neil A., Jane B. Reece, Lisa Andrea. Urry, Michael L. Cain, Steven
Alexander. Wasserman, Peter V. Minorsky, and Rob Jackson. Biology. San Francisco:
Pearson, Benjamin Cummings, 2008. Print.
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<http://www.hometrainingtools.com/pig-dissection-project/a/1320/>.
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Formation." Human Body Organs: Anatomy of Largest , Biggest Organs System
Functions And Formation. Web. 22 May 2012. <http://www.einfopedia.com/humanbody-organs-anatomy-of-largest-biggest-organs-system-functions-formation.php>.
4. Martini, Frederic. Fundamentals of Anatomy and Physiology. Englewood Cliffs, NJ:
Prentice Hall, 1992. Print.
5. Spence, Alexander P., and Elliott B. Mason. Human Anatomy and Physiology. Menlo
Park, CA: Benjamin Cummings Pub., 1987. Print.
6. "Untitled Document." Untitled Document. Web. 22 May 2012.
<http://www.goshen.edu/bio/pigbook/humanpigcomparison.html>.