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Generalized Dissection Guide
Major Organ Systems:
 Integument (the outside covering)
 Circulatory System
o Heart, arteries, veins, capillaries, and blood
 Lymphatic System – pumps plasma back to heart when it leaks out of capillaries
and is home to the majority of white blood cells
o Lymph, lymph nodes and vessels, white blood cells, T- and B- cells –
largest organ is the spleen
 Respiratory System
o Nose, trachea and lungs
 Digestive
o Mouth, esophagus, stomach, small and large intestines
 Excretory System
o Kidneys, ureters, bladder and urethra
 Reproductive
o Female: ovaries, oviducts, uterus, vagina and mammary glands
o Male: testes, seminal vesicles and penis
 Nervous System
o Brain, spinal cord and peripheral nerves
 Sensory Systems
 Skeleton – support and protection
o Bones, cartilage, tendons and ligaments
o Produce white and red blood cells in the marrow
 Muscles – movement both voluntary (swinging a bat) and involuntary (digesting
your food)
o Skeletal and smooth muscles
 Endocrine – hormones to keep you functioning! Hormones control how fast you
grow, maintain your body temperature, fight or run away when scared, and much,
much more!
o Some of the glands of the endocrine system are hypothalamus, pituitary,
thyroid, pancreas and adrenal
For our dissections, you will first examine:
 The Epidermis – outside of the organism. What is the epidermis like? Is it scaly,
smooth, slimy, hairy, or feathery?
 The Sensory – eyes, ears, touch, taste, smell, electro-sensors, lateral line, etc.
 How many appendages (arms and legs), is there a tail, does it have fins? How
about gill flaps or slits?
After recording this information, you will begin to examine the internal anatomy of our
organism.
 Wait until you receive directions on how best to expose the internal anatomy of
the weekly organism. When you make your first cuts, you want to penetrate the
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skin and muscles, but not puncture the internal organs. If you do, however, it is
okay. After all, you are learning how to do this!
Generally, after exposing the internal anatomy, the first organ you see is the liver.
It plays a major role in metabolism and has a number of functions in the body,
including glycogen storage, decomposition of red blood cells, plasma protein
synthesis, and detoxification. The liver is also the largest gland in the human
body. It lies below the diaphragm in the thoracic region of the abdomen. It
produces bile, an alkaline compound that aids digestion, via the emulsification of
lipids. It also performs and regulates a wide variety of high-volume biochemical
reactions requiring very specialized tissues. The liver breaks down toxic
substances and most medicinal products in a process called drug metabolism. The
liver belongs to several different organ systems, digestive, excretory, and
circulatory to name just three. Remove the liver.
Under the liver, you will be able to see part of the esophagus, stomach, small and
large intestines. A simple snip at the esophagus (as high as possible) and a simple
snip at the anus should allow you to remove these organs. You will have to cut or
tear the think membrane that holds all of these parts in place inside this animal.
Remove the digestive tract. How long are the short intestines? Measure the
length of the short intestines. Record the length on your trait chart.
Under the digestive tract, you will see the kidneys and reproductive system. Is
your organism a male or female?
To see the heart and gills/swim bladder/lungs, you will need to cut between the
ribs. Depending on the organism, it may take a bit of strength to do this. Remove
the heart. Cut the heart into 2 halves and count the number of chambers. Record
this on your trait chart.
The swim bladder is found only in bony fish. Our lungs are from the same cells
as the swim bladder. You will find the cavity for the swim bladder in the perch
just underneath the spine. It may be hard to see.
Gills or Lungs? If your animal has gills, you can view them by cutting into them
from the outside. Locate the gill flap or gill slits, and cut deeply into the animal.
They are supported by cartilage, so they will be hard to cut. If you are working
on a terrestrial animal, the lungs will be located to the left and right of the heart.
Remove the lungs, and squeeze to verify that they are spongy, then cut in half.
Sensory System: If there is time, you may remove the eye, and dissect to locate
the different parts of the eye – the lens and retina. Depending on the animal, Barb
will describe how best to view the other sensory organs.
Brain: The brain is encased in cartilage or bone, and is very difficult to dissect.
Depending on the organism and our remaining time, you may only get to look at
one brain exposed by Barb.
To clean up your equipment:
 Do not remove your goggles or gloves until everyone has finished cleaning up.
 Scrape all biological material into the Biohazard bag. Do not dispose of any
tools, the pad or the dissection tray in this bag.
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Wash all tools (tray, pad, scissors, probes, tweezers, and hand lenses) with soap
and water. Rinse thoroughly. Completely dry all equipment (tray, pad, scissors,
probes, tweezers, and hand lenses).
Barb will have a place for you to put each of your tools. Be sure to stack them
neatly.
Using the sponge and Lysol, clean your dissection table/desk. Make an “S” with
the Lysol, and wipe completely.
When everyone has finished cleaning their equipment and tables/desks, you may
remove your gloves (please follow Barb’s directions on how to properly remove
gloves) and they may be tossed into the regular garbage (remember, you washed
all your equipment with soap and water, so your gloves are clean).
Remove your goggles and return them to the goggle stack.
Complete your traits for this organism.
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