Download 9. External Anatomy

Name_______________________________________ Section____________
Lab 9: External Anatomy
OBJECTIVES
1. To Understand anatomical terms, references and definitions.
2. To Identify important external structures of the fetal pig.
3. Review “organs to know.”
MATERIALS NEEDED
Double- injected fetal pigs
Dissecting materials
Gloves
PREPARATION
Read Biology a Guide to the Natural World Chapter 25
INTRODUCTION
Animalia is the kingdom that we are most familiar with and includes organisms such as humans, dogs,
whales, and reptiles (plus much more). In this exercise, you will study the anatomy of a fetal pig, which is
similar to human’s organs and systems.
Mammals are vertebrates having hair on their body and mammary glands to feed their young. The
majority are placental mammals in which the developing fetus grows inside the female’s uterus while
attached to a membrane called the placenta. The placenta is the source of food and oxygen for the fetus,
and also serves to get rid of fetal wastes.
CAUTION: When conducting dissections, laboratory safety VERY IMPORTANT. Because scalpels
will be used, please do not wear any type of sandal. This will prevent a cut if any sharp object is
dropped. Please use gloves at all times if you handle the pig. If any cut or injury occurs, please let
your lab Instructor know immediately.
HELPFUL WEB SITE
This site has the planes of the body. It is a slide show that shows the planes and then it has the anatomical
terms and definitions associated with planes on the last slide. It also has study guides of the major
systems and quizzes.
http://www.whitman.edu/offices_departments/biology/vpd/main.html
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ACTIVITY
I. Anatomical References
Cranial region – Refers to the head
Pelvic region – Refers to the area around the pelvis
Caudal region – Refers to the tail or tail-like structures
Ventral - Refers to the belly
Dorsal – Refers to the back
Medial – Refers to the position near the middle or midline
Lateral – Refers to the side of the body
Proximal - Nearest to the center, to the midline, or to the point of attachment.
Distal – Furthest from the center, from the midline or from the point of attachment
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Note: In human anatomy, the terms anterior and posterior are used instead of ventral and
dorsal, and the terms superior and inferior are used to replace cranial and caudal
ACTIVITY:
II. External features
1. Obtain a fetal pig and lay the pig on its side in the dissecting pan and locate dorsal, ventral, &
lateral surfaces. Also locate the anterior and posterior ends.
2. Examine the pig’s head. Locate the eyelids and the external ears or pinnae. Find the external
nostrils.
3. Locate the umbilical cord. With scissors, cut across the cord about 1 cm from the body.
Examine the 3 openings in the umbilical cord. The largest is the umbilical vein, which carries
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blood from the placenta to the fetus. The two smaller openings are the umbilical arteries which
carry blood from the fetus to the placenta.
4. Lift the pig's tail to find the anus. Study the ventral surface of the pig and note the tiny bumps
called mammary papillary. These are present in both sexes. In the female these structures
connect to the mammary glands.
ACTIVITY
III. Sexing your pig
Determine the sex of your pig by locating the urogenital opening through which liquid wastes
and reproductive cells pass. In the male, the opening is on the ventral surface of the pig just
posterior to the umbilical cord. In the female, the opening is ventral to the anus. Record the sex
of your pig.
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GLOSSARY
Anus - an opening located ventral to the tail where feces is excreted
Caudal region – refers to the tail or tail-like structures
Cranial region –refers to the head
Distal – furthest from the center, from the midline or from the point of attachment
Dorsal –refers to the back
Genital papilla - a projection of tissue dorsal to the urogenital opening
Lateral – refers to the side of the body
Mammary papillae: nipples; indicate how many mammary glands there are
Medial – refers to the position near the middle or midline
Pelvic region – refers to the area around the pelvis
Proximal - nearest to the center, to the midline, or to the point of attachment.
Scrotum - contains the testes
Umbilical arteries - carries oxygen-rich blood to the fetus from the placenta
Umbilical cord - connects the fetus to the mother at the placenta
Umbilical veins - carries deoxygenated blood from the fetus to the placenta
Urogenital opening (female) - opening to the urogenital sinus
Urogenital opening (male) - opening to the urogenital sinus
Ventral - Pertaining to the belly
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