Lab 19: Anatomy of the Frog

frogs and toads phylum

Chordata

frogs and toads subphylum

Vertebrata

frogs and toads class

Amphibia

tadpole

aquatic larval stage of frogs

why do frogs have to live close to water?

they have an aquatic larval stage (tadpole), followed by metamorphosis into a semi-aquatic terrestrial adult; limited ability to conserve body water; often use their skin as a respiratory surface, so they must stay moist

endoskeleton

internal skeleton; allows for much larger growth, protects internal organs, serves as a support structure for muscles to attach to, has great flexibility and mobility due to the large number of separate bones

axial skeleton

skull, vertebral column, sternum/ribs

appendicular skeleton

shoulder girdle, pelvic girdle, limbs

cranium h

mandible h

vertebral column h

clavicle h

scapula h

humerus h

radius h

ulna h

pelvis h

carpals h

metacarpals h

phalanges h

femur h

patella h

tibia h

fibula h

tarsals h

metatarsals h

cranium f

vertebral column f

scapula f

humerus f

radioulna

radius and ulna fused together

carpals f

metacarpals f

phalanges f

pelvic bone f

femur f

tibiofibula

tibia and fibula fused together

tarsals f

long and thin compared to humans

metatarsals f

dorsal

ventral

eyes

Cloacal aperture

The external opening where the digestive, urinary, and reproductive systems empty in a frog.

External nares

The frog’s nostrils that allow air to enter the respiratory system.

webbed feet

Tympanic membrane

The external eardrum that detects sound vibrations.

Flexors

Muscles that bend a joint.

Extensors

Muscles that straighten a joint.

Adductors

Muscles that move a limb toward the midline of the body.

Abductors

Muscles that move a limb away from the midline of the body.

Triceps femoris

extension of leg at knee

Semimembranosus

flexion of leg at knee

Gracilis minor

flexion of leg at knee

Gracilis major

flexion of leg at knee

Sartorius

Legs come together at body’s midline

Adductor longus

Legs come together at body’s midline

Adductor magnus

Legs come together at body’s midline

Gastrocnemius

Extension of foot at ankle (toes move away from shin)

Peroneus

Flexion of foot at ankle (toes move closer to shin)

Coelom

The main internal body cavity that houses the organs.

Peritoneum

layer of epithelium that lines the internal body cavity

Mesenteries

sheets of epithelium that extend from the dorsal body wall to the organs to stabilize them

Pericardium

sac containing the heart

Testes

Male reproductive organs that produce sperm.

Fat bodies

Fat storage structures near the reproductive organs that provide energy for reproduction.

Ovaries

Female reproductive organs that produce eggs.

Oviduct

The tube that transports eggs from the ovaries to the cloaca.

Retroperitoneal kidney

Kidneys located behind the peritoneum that filter wastes from the blood.

Urinary bladder

A sac that stores urine before excretion.

Liver

produces bile; fat digestion

frog digestive system

stomach → pyloric sphincter → small intestine → colon

stomach

digestion begins

pyloric sphincter

regulates passage of partially digested food between stomach and small intestines

colon (large intestine)

absorption of water and ions; undigested waste stored as feces

small intestine

digestion is completed; nutrients are absorbed

gall bladder

stores bile until food enters small intestine for digestion

pancreas

produces bicarbonate (neutralize stomach acid), digestive enzymes; also produces hormones insulin, glucagon

Buccal cavity

The mouth cavity of the frog used in feeding and breathing.

Glottis

opening to lungs, keeps food out

Eustachian tube opening

connects to ear under tympanic membrane

Esophagus

entrance

Maxillary teeth

Small teeth along the upper jaw that help hold prey.

Vomerine teeth

Small teeth on the roof of the mouth that help grip prey.

Tongue

A sticky, elastic structure used to catch prey.

Stomach

An organ where chemical digestion of food begins.

Pyloric sphincter

A muscular valve that controls passage of food from the stomach to the small intestine.

Small intestine

The organ where digestion is completed and nutrients are absorbed.

Colon

The large intestine that absorbs water and stores waste.

Pancreas

A gland that produces digestive enzymes and hormones like insulin.

Gallbladder

A small organ that stores bile produced by the liver.

Spleen

An organ involved in immune function and blood filtration.

Lungs

divided into tiny chambers called alveoli

Positive pressure breathing

A breathing method where frogs push air into their lungs using mouth cavity pressure.

Pulmonary circuit

Right side pumps deoxygenated blood to the lung capillaries where O2 enters the blood and CO2 leaves the blood.

Systemic circuit

Left side pumps oxygen-enriched blood out to the tissues and cells of the body, where blood delivers O2 in exchange for CO2

Heart

The organ that pumps blood through the circulatory system; three chambers: right atrium, left atrium, and ventricle

Left and right atria

The two upper chambers of the heart that receive blood.

Ventricle

The single lower chamber of the frog heart that pumps blood to the lungs and body; can divert blood away from the pulmonary circuit

Axial skeleton

The part of the skeleton that includes the skull, vertebral column, and sternum.

Skull – cranium and mandible

The bones of the head that protect the brain and form the jaw.