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Anatomical
Direction
Before
beginning a dissection, it is important to have an
understanding of some of the basic directional terminology
associated with the dissection of specimens. Some
of these terms include proximal, which means toward the
body, and distal, which means to move away from the
body. Other important anatomical directions are
indicated below.
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Key
Anatomical Directions |
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Dissection Safety
Proper safety
procedures when working with dissection tools and specimens is
of greatest importance. Some safety
rules to engage in when dissecting specimens are as follows.
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Dissection Safety
Rules |
- Follow all instructions given by your
teacher.
- Inform your teacher of any illness as a result of
exposure to chemicals used in specimen preparation.
- Avoid contact with preservative chemicals. Rinse the
specimens completely before dissection.
- Know where the eye-wash fountain is if needed.
- Wear safety goggles to prevent the splashing of any
chemicals into the eyes.
- Properly mount dissection specimens to dissecting
pan. Do not dissect a specimen while holding it.
- Handle scalpel or razor blade (safety edged) with
extreme care.
- Always cut away from your body and away from others.
- Never ingest specimen parts.
- Never remove specimens or specimen parts from the
classroom -- until the dissection is completed all parts
of the dissection must remain within the dissecting pan.
- Properly dispose of dissected materials.
- Store specimens in as directed by your teacher.
- Clean up the work area and return all equipment to
the proper place when the dissection is completed.
- Wash hands after each dissection.
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Dissection
Equipment
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Dissection
Equipment |
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The pictured dissection equipment from left to right is
(1.) a teasing or dissection needle which used to
pull apart muscle tissue, (2) dissecting scissors
which are used to cut through tissue, and (3) a scalpel,
which is a knife used to slice through and cut tissue. |
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Plant Dissection
Many
kinds of flowering plants, such as lilies, daffodils, or
tulips are commonly subjects for dissection in
biology. The flower is the
plant structure specialized for reproduction in advanced
plants. The processes of meiosis and fertilization
occur in the flower.
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Some Key Flower structures |
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petals: colored parts inside the sepals which
attract insects
sepals: structures which are usually green outside the
petals which help to protect the flower
stamen: forms the male reproductive organ and
consists of an anther and a filament
anther: pollen box in which pollen grains are formed
containing the genetic material which produces sperm
filament: supports the anther
pistil or carpel: female reproductive organ which
consists of three parts
stigma: found at the top of the pistil, is often
sticky and hairy adapting it to catch and hold pollen
style: tube-like connection between the stigma and the
ovary
ovary: enlarged part of the pistil attached to
the receptacle (stem tip on which the flower rests) and
contains the ovules
ovules: small white structures within the walls
of the ovary which produces the plant egg cells |
Animal Dissection
The dissection of animals is important for many
reasons. It helps in the learning about the
internal structures of animals. It also allows
students to learn how organs and tissues are
interrelated. Another purpose of dissection
is to allow the comparison of organisms in terms of their
organs and relative complexities.
While
many good simulations of dissections may be observed, it
seldom can replace the benefits of the actual participation in
an actual dissection.
Some
common vertebrate organisms dissected in the living
environment lab include the frog and the fetal
pig. Usually the dissection procedure
involves tying the organism down firmly on the dissection pan,
cutting the organism open on its ventral side (as pictured
below), and pinning its tissues and muscles back to observe
its internal organs. Different teachers may
have their own preferences in terms of their emphasis on the
tissues and organs to be observed in a dissection.
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Key Internal
Organs of the Frog |
| Organ |
Body System |
Major Function |
| brain |
nervous |
thinking and coordination of body activities |
| heart |
circulatory |
pumps blood through the body |
| stomach |
digestive |
stores and begins the chemical digestion of food |
| small intestine |
digestive |
finishes chemical digestion and absorbs digested
nutrients into the blood |
| liver |
digestive (and other systems) |
makes bile, detoxifies poisons, many other functions |
| gall bladder |
digestive |
stores bile from liver for release into small intestine
to aid in fat digestion |
| lungs |
respiratory |
exchanges gases with the external environment (aided by
the skin in the frog) |
| kidneys |
excretory |
filter wastes from the blood |
| ureter |
excretory |
carries wastes to the urinary bladder |
| urinary bladder |
excretory |
stores urine before its release from the body |
| pancreas |
endocrine/digestive |
produces hormones like insulin which regulate blood
sugar, produces pancreatic juice which aids in digestion
in the small intestine |
| ovaries |
reproductive |
makes eggs in female frog |
| testes |
reproductive |
makes eggs in male frog |
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Frog Internal Anatomy |
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Web Resources
Interactive
Frog Dissection (Dr. Mable B. Kinzie,
University of Virginia)
Virtual Pig Dissection (Earl W. Fleck, Ph.D. Whitman
College)
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