Download Name Period _________ Due date _____________ FROG

Name _____________________________________________________ Period _________ Due date ______________________
FROG DISSECTION
External Anatomy
Observe the dorsal and ventral sides of the frog.
What color is the dorsal side?___________________________________________
What color is the ventral side?___________________________________________
Examine the hind legs of the frog.
How may toes are present on each foot?__________________________________
Compare the toes and arrangement of the frog hind leg toes to that of humans.
Examine the forelegs of the frog.
How many toes are present on each appendage?_______________________________
Compare the toes and arrangement of the frog foreleg toes to the fingers of a human.
Use a ruler to measure your frog. Measure from the tip of the head to the end of the frog’s
backbone (NOTE: do not include the legs in your measurement). Compare the lengths of other
frogs to your frog.
Your Frog
(cm)
Frog 2 (cm)
Frog 3 (cm)
Frog 4 (cm)
Frog 5 (cm)
Average (cm)
1|Page
Locate the frog’s eyes. The nictitating membrane is a membrane that is attached to the bottom
of the eye. Use tweezers to carefully remove the nictitating membrane.
What color is the nictitating membrane? _______________________________________
What is the function of the nictitating membrane?
If time permits, you may remove the eyeball.
Label the following on the human eye diagram below
Word Bank
Cornea
Macula
Vitreous gel
Fovea
Optic nerve
Iris
Pupil
Lens
Retina
1
.
2
.
6
.
3
.
4
.
7
.
8.
5
.
9
.
2|Page
Just behind the frog’s eyes is a circular membrane called the tympanic membrane.
Measure the diameter of the tympanic membrane________________________
How does the tympanic membrane function for the frog?
Label the following on the human ear diagram below:
Word Bank
Auditory Canal
Inner Ear
Cochlea
Middle ear
1
.
Eardrum
Outer ear
2
.
4
.
6
.
7
.
3
.
Eustachian tube
Semicircular canal
8
.
5
.
3|Page
Label the following on the frog diagram below:
Word Bank
Dorsal
External Nares/nostril
Posterior
Tympanum
Anterior
Nictitating membrane
4
.
5
.
Eye
Ventral
6
.
1
.
2
.
8
.
3
.
7
.
Pry open the frog’s mouth and use scissors to cut the angles of the frog’s jaw open.
Cut deeply enough so that the frog’s mouth opens wide enough to view the structures inside.
Locate the tongue. Does it attach to the front or the back of the mouth? ____________________________
Sketch the frog’s tongue.
4|Page
In the center of the mouth toward the back is a single round opening that leads to the
esophagus. The esophagus leads to the stomach.
Close to the angles of the jaw are two openings, one on each side. These are the Eustachian
tubes which function to equalize pressure in the inner ear while the frog is swimming. Insert a
probe into the Eustachian tube.
To what structure does the Eustachian tube attach? _________________________________________________
Just behind the tongue and before the opening to the esophagus, is a slit-like opening. This
slit is the glottis and it opens to the lungs of the frog. The frog breathes and vocalizes with the
glottis.
The frog has two sets of teeth. The vomarine teeth are found on the roof of the mouth. The
maxillary teeth are found around the edge of the mouth. Both are used to hold prey in the mouth.
Frogs swallow prey whole, they do not chew.
On the roof of the mouth you will find two tiny openings. Place your probe into these nostril
openings to determine where they exit on the outside of the frog.
Label the following on the diagram of the frog’s head:
Esophagus
Internal nostril
Vomerine teeth
Eustachian tube
Maxillary teeth
1
.
2
.
3
.
Word Bank
External nostril
Mouth
Eye
Tongue
5
.
4
.
6
.
Glottis
Tympanum
7
.
8
. 9
.
10
.
11
.
5|Page
Label the following on the diagram of the human
mouth:
3
4.
.
5
.
Word Bank
Canine
Hard
Incisor
Gingival
teeth
palate
teeth
Molar Premolar
Tongue Tonsils
teeth
teeth
Soft
palate
6
7 .
8
.
.
9
.
1
0.
Lips
Uvula
1
.
2
.
11.
Dissection
Place the frog on the dissecting pan, ventral side up. Use scissors to lift the abdominal muscles
away from the body cavity. (1) Cut along the midline of the body from the pelvis anterior to the
tip of the mouth.
(2) Make transverse (horizontal) cuts near the arms and (3) legs. Lift the flaps of the body wall
and pin back.
6|Page
Locate each of the organs below.
Fat bodies – spaghetti shaped structures that have a bright orange or yellow color. Fat bodies
may need to be removed to see other structures. They are usually located just inside the
abdominal wall.
Peritoneum – A spider web-like membrane that covers many of the organs. You may need to
carefully remove it to get a clear view.
Liver – this is the largest structure of the abdominal cavity. It is brown colored and composed of
three lobes.
Heart – located anterior to the liver. It has a triangular shape. The left and right atrium can be
found at the top of the heart and the single ventricle is located at the bottom.
Lungs – found underneath and behind the liver and the heart. They look like sponges.
Gall bladder – lift the lobes of the liver to find this small green sac.
Stomach – curving from underneath the liver is the stomach.
Pyloric sphincter – follow the stomach to where it empties into the small intestine. This is
where you will find this structure.
Small intestine – the stomach empties into the small intestine. The first portion is called the
duodenum, the curled portion is the ileum. The ileum is held in place by a blood vessel filled
membrane called the mesentery.
Large Intestine – the small intestine empties into the wider large intestine. In the frog it is also
known as the cloaca.
Spleen – in the folds of the mesentery you will find a small dark red spherical structure.
7|Page
Label the following diagram:
Word Bank
Large intestine
Liver
Small intestine
Stomach
Gall bladder
Right atrium
Lung
Ventricle
1
.
2
.
3
.
4
.
5
.
6
.
7
.
8
.
If time permits, remove the stomach and examine the contents.
8|Page
If time permits, remove the small intestine and measure the length.
9|Page
Label the following diagram of the human digestive system:
Word Bank
Gall bladder
Large intestine
Pancreas
Rectum
Esophagus
Mouth
Stomach
Liver
Small intestine
4
.
5
.
1
.
2
.
3
.
6
.
7
.
8
.
9
.
10 | P a g e
Label the following on the diagram of the human heart:
Word Bank
Inferior vena cava
Left atrium
Right atrium
Right ventricle
Aorta
Pulmonary vein
Left ventricle
Superior vena cava
4
.
1
.
5
.
6
.
2
.
7
.
3
.
8
.
The frog’s reproductive system and excretory system are combined into one system called
the urogenital system. You will need to know the structures for both male and female
frogs.
Kidney – flattened bean shaped organs located dorsally at the lower back near the spine. They
are often dark in color.
Testes – in male frogs, these organs are located at the top of the kidneys. They are pale colored
and roundish in shape.
Oviducts – these are curly structures around the outside of the kidney. Males may have a similar
structure which is actually a vestigial oviduct.
Bladder – this is an empty sac located in the most posterior region of the abdominal cavity.
Cloaca – sperm or eggs and urine exit here
11 | P a g e
Label the following in the diagrams of the frog urogenital system:
Male Word Bank
Bladder Cloaca
Fat
Kidney Testes
Female Word Bank
Bladder Cloaca
Eggs
Fat
Kidney Oviduct
1
.
1
.
5
.
4
.
2
.
3
.
4
.
5
.
2
.
3
.
6
.
12 | P a g e
Study and removal of the brain. Turn the frog dorsal side up. Cut away the skin and flesh on
the head from the nose to the base of the skull. With a scalpel, scrape the top of the skull until the
bone is thin and flexible. Be sure to scrape AWAY from you. With your scalpel held almost
horizontally, carefully chip away the roof of the skull to expose the brain. Use scissors to cut
away the heavier bone along the sides of the brain.
Label the following on the frog brain:
Cerebellum
Cerebrum
Word Bank
Medulla oblongata Olfactory lobe
Optic lobe
Spinal Cord
Label the following on the human brain:
Word Bank
Cerebrum
Cerebellum
Medulla oblongata
1
.
2
.
3
.
13 | P a g e
The bones of the frog follow the same basic pattern as other vertebrates. The lower leg of
the frog is a muscular leg that the frog uses for jumping.
Label the following bones on the frog skeleton diagram:
Word Bank
Astragalus
Atlas
Calcaneum
Carpals
Ilium
Metacarpals Metatarsals
Phalanges
Suprascapula
Tarsals
Tarsus
Tibioulna
Femur
Radio-ulna
Rudimentary toe
1
.
Humerus
Sacral vertebrae
Urostyle
10
.
6
.
2
.
11
.
7
.
8
.
9
.
1
4.
15
.
12
.
1
3.
16
.
3
.
17
.
4
.
5
.
18
.
14 | P a g e
Label the following bones on the human skeleton:
Cranium
Patella
Ribs
Word Bank
Carpals
Femur
Metacarpals
Metatarsals
Tarsals
Tibia
Clavicle
Pelvis
Scapula
Fibula
Phalanges
Ulna
Humerus
Radius
Vertebrae
1
.
2
.
10
.
11
.
3
.
12
.
4
.
1
3.
5
.
1
4.
6
.
15
.
7
.
16
.
17
.
8
.
9
.
18
.
15 | P a g e