Download Mammalian Dissection

Mammalian Dissection
The Rat
Rattus norvegicus
Materials
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Lab notebook—everyone writes notes;
everyone not actually working on the rat needs
to draw all diagrams.
Dissecting Pan and Tools
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Scalpel, dissecting scissors, probes
Gloves (if actually dissecting/handling rats)
Plastic bag, labeled with names of students in
group
Rat
Rules
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No eating or drinking at all!
No carving in black wax
No working ahead
No mutilations
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Especially cutting off head or tail
Squishing, squashing, or cutting organs into pieces
No dares—the rat is cured in poisonous
chemicals.
Preserved Rats
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These rats were raised in captivity on a “farm”
Euthanized by gas.
Cuts made at neck and tail/leg and injected
with colored latex dye to remove blood and see
blood vessels
Cured in formaldehyde (carcinogen), then
washed clean and placed in a “safer” juice.
Preserving kills all bacteria, so they do not
spoil until bacteria starts to grow
Rats!
In your lab book- Kingdom: Animal
 Phylum: Chordate
 Class: Mammal
 Order: Rodent
 Family: Muridae
 Genus: Rattus
 Species: norvegicus
Meet your rat
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Give it a good bath under running water for at
least a minute.
Hang upside down for about another minute to
drain.
Dry rat and tray with paper towel.
Mammals are Bilateral
Lab:
1.
Is your rat perfectly bilateral? How is it not?
Mammals are very similar in
structure
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Skeletal
Organ
Systems
DNA
Lab:
2.
3.
Draw a simple rat in your lab notebook.
(almost full size)
Label the following anatomical terms of
location:
Anatomical Terms of Location
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Cranial: The head end
Caudal: The tail end
Anatomical Terms of Location
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Rostral: On the head—toward the nose
Anatomical Terms of Location
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Dorsal: Top (or back)
Ventral: Bottom (or front)
Anatomical Terms of Location
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Proximal: Closer to
the body
Distal: Further from
the body
Right and Left—the
organism’s right and
left!
Anatomical Terms of Location
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Median—the center line of the body
Medial—towards the median
Lateral—away from the median
Planes of the body
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Sagittal—a plane
that divides the body
into left and right
Dorsal—divides the
body in dorsal and
ventral
Transverse—divides
the body in cranial
and caudal
External Features
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Label the head, trunk and tail
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Trunk is divided into the thorax and abdomen,
separated internally by the diaphragm
Label and define the purpose
4.
5.
Nares: nostril covers for protection
Vibrissae: sensory whiskers
Male External Features
6.
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Identify the gender of your animal
Label and define the purpose
7.
8.
Scrotal sac: holds testes at appropriate temp.
Urethral oriface: where urine exits
Female External Features
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Label and define the purpose
9.
Mammary papillae: nipples
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How many are there?
10. Vaginal oriface: baby rats exit
The Skull
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Draw and Label and define the purpose
11.
12.
13.
14.
Maxilla: upper jaw
Mandible: lower jaw
Incisors: front teeth for cutting
What did the rat probably eat in the wild? Grasses
and grains
Teeth
15. Draw and Label the different teeth in the
mandible
–
Molars, premolars, incisors
Muscular System
16.
What are three
basic purposes
for muscles?
Movement (of
skeleton), protection
(of organs), function
(of organs such as
stomach, heart)
Skeletal Muscle
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First, you must partially skin
the rat.
Do not cut through any
muscle!
Muscles to Define
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17. Masseter— jaw muscle, to close mouth
18. Pectoralis— chest muscle, push forelimbs
19. Triceps— forelimb muscle, extend
20. Biceps— forelimb muscle, bend
More Muscles
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21. Abdominal
oblique— move
abdomen all directions,
protect and hold “guts”
22. Quadriceps— hind
Leg group muscles to
extend
23. Gastrocnemius—
calf muscle, extend toe
Digestive System
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24.
25.
26.
Use scissors to cut the tissue at the back of the
jaw to “flip” open the mandible.
Find and define:
Hard Palate— ridged; helps hold and chew food
Soft palate— smooth; helps swallow
Epiglottis— opens/closes to the trachea
Opening the Abdominal Cavity
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Make an incision
below the pectoralis
down almost to the
tail.
Scissors are easy.
Make lateral
incisions to lay back
the abdominal
muscles.
Draw and Label Organs in the
Abdominal Cavity
27.
28.
29.
30.
31.
32.
33.
34.
Liver--find functions sin
guide.
Stomach
Spleen--immunity
Small intestine—
absorbs nutrients
Cecum—digests
cellulose
Large intestine/colon—
absorbs water
Rectum—function (holds
feces, not location
Pancreas—makes
insulin and other
hormones, function, not
location
Draw the
Urinary System
35. Kidneys—filter the nitrogen
wastes from blood
36. Renal artery—carries
unfiltered, but oxygenated
blood to kidney
37. Renal vein—carries filtered,
but deoxygenated blood from
kidney
38. Ureter—carries urine to
kidney
39. Urinary bladder—stores
urine
40. Urethra—carries urine out of
bladder
Male Reproductive System
41. Testes—makes sperm
cells and testosterone
42. Epididymis—stores sperm
cells
43. Vas deferens—carries
sperm from testes to
prostate
44. Prostate gland—adds
seminal fluid
45. Coagulating and Vesicular
Glands—adds to seminal
fluid, makes it coagulate
Female Reproductive System
46. Ovary—makes
female gametes
47. Oviduct—
carries ovum
48. Uterine horns—
where fetus’
develop
49. Uterus—where
the uterine horns
meet (not where
baby rats
develop)
Remove and review these
structures—Keep intact!
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Liver
Spleen
Stomach,
small intestine,
cecum
Draw the Thoracic Cavity
Use scissors to cranially cut
the sternum to the neck.
50. Diaphragm—separates
thoracic cavity from
abdominal. Moves to allow
air in and out of lungs
51. Thoracic Cavity—holds
heart and lungs
Neck:
51A. Carotid artery—carries
oxygenated blood to the
head
51B. Jugular vein—carries
deoxygenated blood back to
the heart from the head
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Respiratory System
52. Trachea—breathing tube
53. How many lobes of the lungs are there? (3 or
4)
Circulatory System
54. How many chambers in a
mammal heart? four
55. Aortic arch—aorta bending
around to go down to the body.
56. Cranial Vena Cava—carries
blood from the body to the
heart (stained blue)
57. Descending aorta—carries
blood to the body (stained red)
58. Caudal Vena Cava—carries
blood from the head to the
heart (stained blue)
Endocrine System
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59.
60.
Responsible for
making
hormones
Adrenal Gland—
makes adrenalin
Thymus—makes
T-cells (white
blood cells) for
the immune
system
Review your entire rat
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Practice finding and naming the anatomical
terms of location
Review your entire rat
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Practice finding
and naming the
structures
4 – 61!