Frog
External Structures
• Eye
– Iris- enlarges or reduces the size
of the pupil in response to
varying amounts of light
– Pupil- opening for light to come
in
– Nictitating membrane- extra
transparent eyelid at the bottom
of the eye
• Nostrils on top of mouth open
into frog’s mouth
• Tympanic membrane- serves
as an eardrum, transmitting
sound vibrations to the ear
cavity
Digestion
1. Gullet
• Tadpoles are herbivores
2. Short esophagus
3. Stomach- enlarged portion of the • Adult frogs are carnivores
digestive tract that serves as a
storage sac and site of preliminary
digestion
4. Pylorus- narrow region of stomach
containing a muscular pyloric
valve which controls the further
passage of food
5. Small intestine consisting of the
duodenum and then the ileum
absorbs dissolved food into the
bloodstream
6. Colon or large intestine
7. Short tubular cloaca- common
passageway for solid and liquid
waste as well as eggs and sperm
during reproduction
Mouth
• Large sticky tongue attached at the
front of the mouth
• Internal nostril openings in roof of
mouth
• Openings to eustachian tubes unite
the ear cavity with the mouth,
located at the back corners of the
mouth
• Gullet- passage to the digestive tract,
opening to esophagus
• Glottis- swelling with slender
opening leading to the lungs
• Males have openings in the back of
the lower jaw that lead to the vocal
sacs
• Teeth- grasping not chewing
– Ridge of tiny maxillary teeth in the
upper jaw
– Two sets of vomerine teeth between
the internal nostril openings
Digestion
•Liver- 3 lobed gland, produces
bile which aids in digestion, also
stores some digested food
•Gallbladder- stores excess bile
•Pancreas- this gland is a small
strip of tissue near the stomach,
produces digestive enzymes
•Bile duct- secretions from the
liver, gallbladder, and pancreas
are passed to the small intestine
through the bile duct
•Mesenteries- transparent
membranes that enclose all the
digestive organs and connect the
organs to the dorsal body wall,
contain blood vessels
Respiration
• Frog obtains
oxygen by using its
skin, mouth lining,
and lungs.
• Frog does not
have muscles
needed to inhale
and exhale like
humans do. Frog
essentially
swallows the air.
1.
2.
3.
4.
Mouth
Glottis
Trachea
Lungs
Circulation
Excretion
• Kidneys
• long red brown structures
against the dorsal body wall
• Filters waste and excess water
from the blood and
concentrates it into urine
• Urinary bladder
• Cloaca
Reproduction
• Female
• Ovaries- produce eggs
• Oviducts- long coiled tubes lined with
cilia
• Uterus- stores eggs
• Cloaca- ejects eggs during mating
• Male
• Testes- produce sperm
• Vasa efferentia- passageway for sperm
from testes through kidneys to cloaca
Amplexus- male clasps or wraps around the female which stimulates the
female to release her eggs. As they exit the females cloaca they are
covered by the male in milt which contains sperm.
Nervous System
• Central nervous system
– Brain- encased in skull
– Spinal cord- encased in spinal column
• Peripheral nervous system
– Nerves that transmit impulses between
the central nervous system and the
frog’s muscles and sensory organs
Divisions of the Five major lobes of the brain, from anterior to posterior:
1.
Olfactory lobes ~ receive impulses from the smell receptors of the nostrils
2.
Cerebrum ~ controls voluntary muscle activity
3.
Optic lobes ~ Receives impulses from the eyes
4.
Cerebellum ~ coordinates muscle activity and some involuntary activities
5.
Medulla oblongata ~ transports impulses to and from the spinal cord, including
some reflexes.
Nervous system contains:
1.
Brain
2.
Spinal cord
3.
Cranial nerves (branch from the brain)
4.
Spinal nerves (branch from the spinal
cord)
5.
Sensory organs( eyes, ears, taste
buds)
Divisions of the Five major lobes of the
brain, from anterior to posterior:
1.
Olfactory lobes ~ receive impulses
from the smell receptors of the
nostrils
2.
Cerebrum ~ controls voluntary muscle
activity
3.
Optic lobes ~ Receives impulses from
the eyes
4.
Cerebellum ~ coordinates muscle
activity and some involuntary
activities
5.
Medulla oblongata ~ transports
impulses to and from the spinal cord,
including some reflexes.
Nervous System