Frog Anatomy

Introducing the Frog:Belong to the group vertebrates• Vertebrates include: sharks, fishes, amphibians, reptiles, birds ,and mammals• All vertebrates have a back bone and a body that is made of a head, trunk, and tail with

paired limbs.Frog belongs to the class: Amphibia• This includes salamanders, caecilians, frogs and toads.• Frogs and toads make up 87% of all amphibians.• This is a class known as the evolutionary transition from water to land.For this to occur certain adaptations in the adult body had to be made.• The formation of lungs to breathe air• Double circulatory system to accommodate lungs• Formation of limbs to move on land• A more rigid endoskeleton

Lungs – an efficient method for terrestrial animals to obtain oxygen.Double circulatory system – • Systemic circuit – supplies blood to the body.• Pulmonary circuit – supplies blood to the lungs.Amphibians reproduce eggs and are laid in water.• Amphibian larvae live there lives in aquatic environment. • Tadpoles – have gills and a tail for swimming.Frogs live what is called a “Dual Life”

Bilateral symmetry – animal can be divided into an equal mirror image called the sagittal plane.Frontal planes and transverse planes are two other types of planes.

Anterior – refers to the head regionPosterior – refers to the tail regionDorsal – refers to the back regionVentral – refers to the belly region

External Structures – Pattern and color on the frogs dorsal side is designed for camoflauge in green vegetation and the underside is light to camoflauge the frog when it swims across the top of the water.Structures and functions of the external structures – • 1. Tympanic membrane – separates the outer environment from the middle ear.• 2. Eye with the nictating membrane – Membrane protects eyes under water.• 3. Maxillary teeth – Help frogs hold their prey and feed mostly on insects.• 4. External nare – Move air into the mouth through the internal nares.• 5. Vomerine teeth – Also hold prey, and are angled in.• 6. Internal nare – Area where air is drawn into from the external nare.• 7. Opening to the Eustachian tube – Tubes that connect to the middle ear and equalize air pressure in

the head.• 8. Glottis – thin opening to the larynx and to the esophagus.• 9. Tongue – extend out from mouth.• 10. Mandible – lower jaw.• 11. Opening to the vocal sac – Only found in males, help vocalize.

The Skeleton – • The skeleton is divided into two parts: The Axial and Appendicular skeleton• Axial skeleton includes:

• Skull• Vertebral column• Sternum

• Appendicular skeleton includes:• Pectoral girdle• Pelvic girdle• Appendages

• Frogs have a more rigid skeleton and an inflexible vertebral column.• This helps transform the energy of the powerful hind legs into the movement of the body.

• 1. Atlas; 2. Exoccipital• 3. Frontoparietal; 4. Sphenethmoid• 5. Nasal; 6. Vomer• 7. Premaxilla; 8. Maxilla; 9. Pterygoid• 10. Squamosal; 11. Quadratojugal• 12. Clavicle; 13. Coracoid• 14. Humerus; 15. Radioulna• 16. Vertebral column• 17. Prepollux; 18. Phalanges• 19. Metacarpals; 20. Carpals; 21. Scapula• 22. Suprascapula; 23. Sacral Vertebra• 24. Urostyle; 25. Ilium; 26. Pubis• 27. Ischium; 28. Femur; 29. Tibiofibula• 30. Astragalus; 31. Calcaneum• 32. Prehallux; 33. Metatarsals; 34. Phallanges

Muscular system – • Have some of the same muscles as humans since they are quadrupeds.• There are two types of actions that describe all muscle:• Flexion – Bending a joint so that the angle of that joint decreases.

• Ex: Bending your elbow or knee.• Extension – extending a joint so that the angle of the joint increases.

• Ex: Straightening out your arm or leg.

• 1. Dorsalis scapulae; 2. Depressor mandibularis• 3. Temporalis; 4. Deltoid; 5. Triceps brachii• 6. Extensor carpi ulnaris; • 7. Extensor digitorum communis• 8. Anconeus; 9. external oblique• 10. Latissimus dorsi; 11. Iliolumbaris• 12. Triceps femoris; 13. Biceps femoris• 14. Gastrocneumius; 15. Peroneus• 16. Gracilis minor; 17. Semimembranosus• 18. Piriformis; 19. Gluteus

• 1. Mylohyoid; 2. Sternoradialis; 3. Pectoralis major• 4. Cutaneous pectoralis; 5. Rectus abdominus• 6. Deltoid; 7. Extensor carpi radialis• 8. Flexor carpi ulnaris; 9. Flexor carpi radialis• 10. Pectoralis major; 11. Linea alba • 12. External oblique; 13. Sartorius• 14. Adductor magnus; 15. Gracilis minor• 16. Gastrocnemius; 17. Tibialis posterior• 18. Gracilis minor; 19. Triceps femoris• 20. Adductor longus; 21. Extensor cruris• 22. Tibialis anterior longus

Digestive System – Alimentary canal – runs from mouth to anus.Pharynx – where food enters mouth.Esophagus – passageway from mouth to stomach.Stomach – Breaks down food through muscle contractions and acids.Pyloric valve – a valve that separates the stomach from the small intestineSmall intestine – Nutrient absorption and digestion. • Duodenum – first part of the small intestine.• Ileum – The portion of the intestine that is curved.Large intestine – Digests bacteria, reabsorbs water, and forms feces. Cloaca – Receives waste from kidneys, fluids from reproductive organs, and large intestine.• It is a common opening for waste products inside the body.Liver, gallbladder, and pancreas – all digestive glands that help the digestive process.

The Internal Organs – • Lungs – have a spongy texture and appearance. Transfers oxygen to the circulatory system.• Pancreas – Located between the stomach and small intestine.

• It is cream in color and lumpy in texture. • It secretes pancreatic juices into small intestine. • Also produces insulin, glucagon, and other hormones that are important in the regulation of sugar levels

and metabolism of fats and carbohydrates.

• Spleen – Very small and produces macrophages• Macrophages engulf and digest foreign cells and dead cells.• They eat old red blood cells, platelets, and bacteria.• The spleen removes the iron and other useful components before breaking down a blood cell.

• Fat bodies – Located near the kidneys.• They are energy reserves.

• Ovary – Site where eggs are produced and also hormones.• Kidney – Excretes ions, water, and other nitrogenous wastes.

• Waste leaves body in the form of urea and ammonia and frogs can get rid of this waste through their skin.

• Urinary bladder – Where urea and ammonia are stored until it is released through the cloaca.

• Mesentery – double membrane that attaches the alimentary canal to the body wall.• Contains many blood vessels, lymph vessels, and nerves.

• Gallbladder – Round “pea-green” structure on the under surface of the right lobe of the liver.• Stores and concentrates bile secreted by the liver and delivers it to the duodenum through the

common bile duct.• Bile digests and absorbs fats.

• Liver – Larges organ inside body.• Metabolizes carbohydrates and fats• Produces bile.• Disposes of old red and white blood cells.• Contains hepatocytes that contain enzymes that detoxify poisons.

• Heart – Three chambered heart that pumps blood throughout the body. • It consists of the right & left atrium, and a central muscular ventricle.

• 1. Esophagus; 2. Left lung; 3. Stomach• 4. Pancreas; 5. Spleen; 6. Fat bodies• 7. Ovary; 8. Kidney; 9. Urinary Bladder• 10. Cloaca; 11. Large intestine• 12. Small intestine; 13. Mesentery• 14. Gall bladder; 15. Lobes of the liver• 16. Heart

Respiratory system – Positive pressure breathing – gulping air into the lungs since they lack a diaphragm.Negative pressure breathing – mammals do this by pulling air down into the lungs through the contraction of the diaphragm.Cutaneous respiration – ability to breathe through the skin.Urogenital (reproductive & excretory) system – • Fertilization is external• Eggs are released into the water as they are being fertilized.

• Aorta – supplies highly oxygenated blood into the lower extremities of the body.• Posterior vena cava – Extends to upper and lower extremities of the body.

• Transports deoxygenated blood from the extremities to the heart.

• Ureter – Transports urine to the urinary bladder.• Seminal vesicle – pair of glands close to the ureters.

• Secrete and produce semen.

• Adrenal gland – located in the kidney.• Produces hormones that regulate salt and act as a “flight” or “fight” response.

• Testis – produce sperm and hormone testosterone.• Ovary – site of the creation of mature eggs and produces hormones related to

reproduction.• Oviduct – transports the eggs from the ostia to the uterus.• Ostium – the ostia are the openings to the oviducts that receive the eggs from

the body cavity.

• 1. Aorta; 2. Posterior vena cava• 3. Fat bodies; 4. Kidney; 5. Ureter• 6. Large intestine; 7. Cloaca• 8. Urinary bladder; 9. Seminal vesicle• 10. Adrenal gland; 11. Testis

• 12. Aorta; 13. Posterior Vena Cava• 14. Ovary; 15. Large intestine; 16. Cloaca• 17. Uterus; 18. Urinary bladder• 19. Ureter; 20. Kidney; 21. Adrenal gland• 22. Fat bodies; 23. Oviduct; 24. Ostium

Circulatory System – Arteries – Carry blood away from the heartVeins – Carry blood toward the heart.Double circulatory system – • Systemic circuit – supplies blood to the body • Pulmonary circuit – supplies blood to the lungs.Mammals have a four chambered heart where the two circuits are completely separated.• Right side serves the pulmonary circuit and left serves the systemic circuit• Left and right atria and ventricles are completely separatedAmphibians - Heart consists of three chambers• Partial separation of the systemic and pulmonary circuits.

• 1. Right atrium; 2. Left atrium• 3. Ventricle; 4. Internal carotid• 5. Internal jugular • 6. Conus arteriosus • 7. External carotid; 8. External jugular• 9. Subclavian artery • 10. Subclavian vein • 11. Pulmonary arteries & veins

• (leads to lungs)

• 12. Celiac artery• 13. Hepatic portal vein• 14. Celiacomesenteric artery

• (to stomach)

• 15. Ventral abdominal vein

• 16. Sciatic artery; 17. Sciatic vein• 18. Common iliac artery• 19. Femoral artery; 20 Femoral vein• 21. Renal portal vein; 22. Aorta• 23. Inferior vena cava• 24. Systemic arch

Nervous system – • Distributes sensory and motor impulses• Nerve impulse – electrical signal transmitted along neurons.• Central Nervous System (CNS) – consists of brain and spinal column• Peripheral Nervous System (PNS) – connects the central verves to the organs and other

regions of the body.• Autonomic Nervous System – cranial nerves associated with involuntary body processes

such as the heart rate, blood pressure, breathing, and digestion.

The Frog Brain1. Olfactory nerve2. Optic nerve3. Oculocomotor nerve4. Trochlear nerve5. Trigeminal nerve6. Abducens nerve7. Facial nerve8. Acoustic nerve9. Glossopharyngeal nerve10. Vagus nerve11. Branch of the sympathetic trunk

(Not part of the cranial nerves)

Eye ball and eye lid movement

Motor nerve for superior oblique muscleSensations in face and motor neuron for biting.

Motor nerve for eye

Motor and sensory nerve for pharynx and tongue

Controls all involuntary movement.

Branches for the nerves coming off of the spinal cord

The Frog Brain• 12. Spinal cord• 13. Jugular ganglion• 14. Medulla oblongata• 15. Pituitary gland• 16. Prootic ganglion• 17. Infundibulum• 18. Optic chiasma• 19. Diencephalon• 20. Cerebrum• 21. Olfactory lobe

Nervous system• 1. Sympathetic nerves; 2. Cerebrum• 3. Olfactory nerves; 4. Olfactory lobe• 5. Optic nerve; 6. Optic lobe• 7. Brachial plexus containing nerves

• (Containing nerves 1 – 3)

• 8. Radial nerve; 9. Ulnar nerve• 10. Abdominal nerve• 11. Nerves 4 – 6 (leading to abdomen• 12. Sciatic plexus containing nerves 7 – 9 • 13. Sciatic nerve• 14. Tibial nerve• 15. Peroneal nerve• 16. Filum terminale• 17. Spinal cord