DIGESTIVE SYSTEM

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DIGESTIVE SYSTEM
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Introduction

• concerned with the function of nutrition which
  includes ingestion, digestion, absorption and
  egestion
• process of digestion involves the physical and
  chemical breakdown of food to render it soluble
  and ready for reabsorption
• tongue and teeth help in mechanical breakdown of
  food
• chemical digestion occurs with help of digestive
  juices containing enzymes secreted by the
  digestive glands
• secretion of enzymes is basically under the
  control of hormones
• passage of food along the digestive tract is
  aided by gut motility controlled by nervous system

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Incomplete Type

• when anus is absent, mouth serves for ingestion
  of food and egestion of waste materials
• Fasciola or Clonorchis
• Parts
• mouth anterior end
• oral sucker circular and muscular sucking
  disc surrounding the mouth
• pharynx short muscle
• esophagus short tube from the pharynx
• additional for Fasciola
• side branches or diverticula of the intestines
  are very prominent and seem to fill the body

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COMPLETE TYPE

• mouth and anus are present
• may be subdivided into the digestive tract, the
  digestive glands, and the accessory structures

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Coelom, Peritoneum, and Mesenteries

• Coelom
• cavity containg the visceral organs
• divided into
• a. small pericardial cavity contains the heart
• b. larger pleuro-peritoneal cavity which
  contains the rest of the visceral organs
• Peritoneum
• connective tissue membrane that lines the
  coelom
• Types
• a. parietal peritoneum lines the body wall
• b. visceral peritoneum covers most visceral
  organs

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Coelom, Peritoneum, and Mesenteries

• Mesenteries
• two layers of the peritoneum that suspends
  viscera from the dorsal body wall
• name of organ they suspend
• Omentum
• double membrane continuous with the mesenteries
  that connect the visceral organs with one another
• also named after organ they connect

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Buccal Cavity

• large cavity exposed upon opening the mouth
• Parts
• maxillary teeth in the upper jaw
• sticky tongue located at the floor of the
  cavity which captures food and passes it on the
  esophageal opening
• glottis slit-like opening to the respiratory
  system and is found at the region between the
  tongue and esophageal opening
• vocal sacs where pair of slits lead to slits
  are located lateral to the glottis and near angle
  of jaw
• choanae or internal nares- pair of holes at the
  roof of the buccal cavity
• vomerine teeth- pair of v-shaped formations at
  the root of the mouth
• Eustachian tube opening or recess near the
  angle

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1. Vomerine Teeth
2. Internal Nares

3. Opening to the Eustachian Tube 4. Maxillary
Teeth
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Digestive Tube

• esophagus
• short tube connecting the oral cavity to the
  stomach
• 2. Stomach
• bag shaped muscle
• Parts of stomach
• a. cardiac end anterior portion continuous
  with the esophagus
• b. pyloric end posterior portion continuous
  with the small intestine
• c. greater curvature outer curvature
• d. lesser curvature inner curvature
• e. rugae lines of the inner wall of the
  stomach
• 3. pyloric sphincter
• constriction at the junction of the stomach
  and the small intestine

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Digestive Tube

• 4. Small Intestine
• - digestive tube that has become the long coiled
  structure from the pylorus
• - where most chemical digestion and absorption
  occurs
• Has 2 regions
• a. duodenum bends anteriorly from the pylorus
  and runs parallel to the stomach
• b. ileum longer and posterior
• 5. Large Intestine
• - where digestive tube enlarges
• - further breakdown of undigested material by
  bacterial action and the absorption of water
  occur here

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Digestive Tube

• 6. Cloaca
• short narrow tube which opens to the outside
  through the anus
• - urine and gametes also pass through the cloaca
  and anus
• Mesenteries found in digestive system
• dorsal mesentery digestive tube is suspended
  from the dorsal body
• mesogaster mesenteries in the stomach at its
  cardiac end
• mesentery proper or mesenterium suspends the
  ileum
• mesorectum suspends rectum
• Spleen
• dark lymphoid organ lying within the fold of
  the mesorectum

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Parts of the Digestive System 3. Spleen 4.
Liver 5. Stomach 6. Small Intestine 7. Large
Intestine
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RESPIRATORY SYSTEM
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Types of Respiratory Organs

• 1. gills
• - aquatic animals
• 2. lungs
• evaginations (outpocketings )of the digestive
  tube for terrestrial animals
• 3. tracheal system
• invaginations of the integument (inpocketings)

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TYPES OF RESPIRATORY SYSTEM
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AQUATIC RESPIRATORY SYSTEMS

• Gills of Fishes
• -are delicate comb-like structures
• a. Operculum covers the gills
• b. Gill chamber part of the pharynx
• c. Gill arches bony structures where gills are
  arched
• d. Gill filaments arranged in parallel rows in
  rich in blood capillaries, this also gives the
  dark red color of the gills in live or fresh
  specimen
• e. Pharyngeal clefts- wide slits between the gill
  arches which serve for the passage of water from
  the pharynx to the gill chamber
• Breathing Movements of Fishes
• water is taken in through the mouth and made to
  pass through the gills then expelled out of the
  gill chamber through the gill aperture

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TERRESTIAL RESPIRATORY SYSTEMS

• Tracheal System of Insects
• respiratory organs consists of a branching system
  of air tubes which supplies oxygen directly to
  the tissues
• Parts
• tracheal trunk short segmental branches that
  lead outside to spiracles and in fine branches,
  the tracheoles, connected directly to the tissues
• spiracles where exchange of gases occur

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TERRESTIAL RESPIRATORY SYSTEMS

• Lung System of Vertebrates
• Parts
• glottis median slit, posterior to the tongue
  which leads to the larynx
• arytenoids pair of cartilages on both sides of
  the glottis which is covered by mucous
• cricoid cartilage ring shaped cartilage that
  borders arytenoids
• vocal cords a pair of elastic, thread-like
  bands
• lungs pair of spongy sacs where larynx leads to
  

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Excretory System
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Frogs Excretory System

• Kidney
• flat, ovoid reddish organs lying in a space
• retroperitoneal
• adrenals maybe observed as the yellowish streaks
  on the ventral surface
• Cisterna Magna
• space between the muscles of the dorsal body wall
  and the peritoneum
• Mesonephric or Wollfian Duct
• thread like tubular structure on the lateral side
  of each kidney
• continues posteriorly beyond the kidney and
  enters the cloaca separately on its dorsal wall
• Urinary Bladder
• connected to the ventral wall of the cloaca which
  serves as storage of urine

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Parts of the Excretory System 8. Kidney 9.
Urinary Bladder
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Mammalian Kidney

• Kidney substance is easily divisible into two
  regions
• outer cortex
• - contains the microscopic renal corpuscles and
  tubules
• inner medulla
• - contains collecting tubules that open at the
  renal papilla
• Renal Pelvis
• - where renal papilla opens
• - expanded beginning in the ureter or
  metanephric duct
• Metanephric Duct
• leads tourinary bladder
• Ureter
• closely associated with blood vessels
• all are found in a concavity called the hilus

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CIRCULATORY SYSTEM
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Function of the Circulatory System

• Responsible for the transport of gases,
  nutrients, metabolic wastes, hormones and other
  substances in the different parts of the body.
• It assists in maintaining constancy of the
  internal environment (homeostasis) of the organism

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OPEN SYSTEM

• Heart
• Pericardial sinus ? cavity where the heart lies
  open at the posterior end
• Dorsal Diaphragm ? membrane forming the ventral
  wall of the pericardial sinus
• Aorta ? vessel from the anterior end of the
  heart, which opens into the sinuses of the head
• Composed of a series of chambers
• Ostia paired lateral openings at the posterior
  end of each chamber which are guarded by valves

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Path of Blood

• Colorless blood from the pericardial sinus enters
  each chamber thru these openings.
• Blood is kept in circulation by the rhythmic
  contraction of the chambers of the heart from the
  posterior to the anterior chambers of the aorta
• Blood then permeates into the different parts of
  the body and finally returns to the pericardial
  sinus through the posterior opening.

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CLOSED SYSTEM

• Blood Vascular System
• Composed of
• a. Blood
• b. Heart
• - pumping action of the heart creates pressure
  that drives - the blood to the different parts
  of the body
• c. Arteries
• - conveys blood from the heart to the different
  parts of the body
• d. Veins
• - convey blood back to the heart
• e. Capillaries
• - connect arterioles with the venules
• Arterioles ? small arteries
• Venules ? small veins

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Lymphatic System

• Composed of
• Lymph vessels
• Lymph spaces
• Lymph ? circulating fluid
• Where is it located?
• Dorso-lateral subcutaneous connective tissue
• ? Tissue connecting the skin to the body wall
• Dorsal subcutaneous lymph space
• ? space between the skin and the dorsal body
  wall
• ? where lymph is pumped into veins by lymph
  hearts
• Lymph Hearts
• ? Contractile hearts found between the third
  vertebra and the posterior corners of the
  suprascapula
• Anterior Abdominal Vein
• ? underneath the linea alba

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HEART

• a. Pericardial cavity
• ? where the heart lies
• ? separated from the pleuroperitoneal cavity by
  the transverse septum
• b. Parietal pericardium (pericardial sac)
• ? lining of the heart which continues as the
  visceral pericardium
• c. Visceral pericardium
• d. Transverse Septum
• ? Separates the pericardial cavity and the
  pleuroperitoneal cavity
• e. Pleuroperitoneal Cavity
• ? contains the visceral organs (minus the heart)

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CHAMBERS OF THE HEART

• Sinus venosus
• ? Dark colored triangular structure, connected
  to the ventral wall of the right atrium
• Left and Right atria
• ? anterior, thin walled
• Ventricle
• ? posterior, thick walled
• Conus arteriosus
• ? bulb like, lies obliquely on the dorsal wall
  of the right atrium
• ? base of all the arteries
• ?arises from the antero-ventral side of the
  ventricle
• Contraction ? Systole
• Relaxation ? Diastole

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• Ventral Aspect
• Ventricle
• Right Atrium
• Left Atrium
• Conus Arteriosus
• Truncus Arteriosus
• Pulmocutaneous Artery
• Systemic Artery
• Common Carotid Artery

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• Dorsal Aspect
• Ventricle
• Right Atrium
• 3. Left Atrium
• 4. Sinus Venosus
• 5. Pulmonary Vein
• 6. Pulmocutaneous Arches
• 7. Systemic Arches
• 8. Common Carotid Arches

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VENOUS SYSTEM

• Principal Divisions
• Systemic
• ? carry unoxygenated blood from the different
  parts of the body directly to the right atrium
• Portal
• ? carry unoxygenated blood through a system of
  blood capillaries in the liver or kidney from
  where the blood is recollected by systemic veins
  to be brought back to the right atrium of the
  heart
• Pulmonary
• ? carry oxygenated blood from the lungs directly
  to the left atrium

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VEINS

• Left/Right Precaval veins
• ? a.k.a. anterior vena cava
• ? big blood vessels entering the Sinus venosus
  antero-lateral angles
• Postcaval vein
• ? a.k.a. posterior vena cava
• Veins connected to the Anterior vena cava
• a. External jugular vein
• ? anterior
• b. Innominate vein
• c. Subclavian vein
• ? Brachial vein
• ? Musculocutaneous vein

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PORTAL VEINS

• Hepatic Portal System
• Consist of the
• Hepatic portal vein
• ? drains blood from the following tributaries
• gastric vein from the stomach
• splenic vein from the spleen
• pancreatic vein from the pancreas
• intestinal veins from the small intestines
• Ventral abdominal vein
• ? brings the drained blood to the liver
• b. Hepatic vein

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PORTAL VEINS

• Renal Portal System
• Consist of the
• a. Renal portal vein
• ? lies on the lateral margin of the kidney
  alongside the mesonephric duct
• b. Veins that drain from the dorsal body wall
• c. Oviduct (for females)
• d. Femoral vein
• ? anterior and dorsal sides of the thigh and the
  rest of the hindlimb
• e. Pelvic vein
• ? medial branch of the femoral vein before
  joining the renal portal vein
• ? course along the posterior abdominal wall,
  where they receive short veins from the urinary
  bladder, and then
• ? unite ventrally to form the anterior abdominal
  vein
• f. Sciatic vein
• ? posterior side of the thigh

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Pulmonary Veins

• ? from the lungs they enter the left atrium

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ARTERIAL SYSTEM

• Arteries
• thick-walled, light colored, generally deeply set
  in the body
• blood flow is pulsating or in spurts
• carry oxygenated blood (minus the pulmonary
  artery)

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ARTERIAL SYSTEM

• Ventral Side of the Heart
• Conus arteriosus
• ? arises from the right antero ventral side of
  the ventricle
• ? serves as the base of all arteries
• Truncus arteriosus
• ? anterior of the conus arteriosus
• ? immediately divides into the left and right
  trunks

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Arteries connected to the Truncus arteriosus

• Common carotid artery
• anterior branch
• divides into two branches
• Internal carotid artery
• carotid gland ?round yellowish gland located
  near the base
• External carotid artery
• Systemic artery
• middle branch
• arches dorsally and posteriorly
• gives small branches to the
• Larynx, muscles of the jaw, dorsal side of the
  esophagus, orbit, nose, vertebral column
• Pulmocutaneous Artery

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Branches of Systemic Artery

• Subclavian artery
• ? supplies the shoulder and neighboring parts
• ? brachial artery subclavian artery that
  continues to the forearm
• Pulmocutaneous artery
• ? posterior
• Dorsal Aorta
• ? posterior continuation of the unified left and
  right systemic arches
• Coeliaco-mesenteric artery
• ? arising ventrally at the junction of the
  systemic arches and dorsal aorta
• ? divides into the
• coeliac artery
• anterior mesenteric artery

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Branches of Systemic Artery

• Posterior mesenteric artery
• ? unpaired artery near the posterior end of the
  aorta, arising from its ventral side
• Left/Right common Iliac arteries
• ? the split of the posterior end of the aorta
• Femoral artery
• ? small dorsally directed artery posterior to
  the common iliac
• ? supplies blood to the skin and muscles of the
  anterior part of the thigh
• Sciatic artery
• ? common iliac artery that proceeds to the rest
  of the hindlimb

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Internal Structure of the Frogs Heart and Its
Branches

• a. Right Atrium
• ? larger thin walled chamber of the heart
• b. Left Atrium
• ? smaller thin-walled chamber of the heart
• has openings on its dorsal wall near interatrial
  septum for pulmonary veins
• c. Interatrial septum
• divides the left and right atrium
• d. Sinoatrial aperture
• ? oval opening on the dorsal wall of the right
  atrium
• ? serves as the entrance of blood from the sinus
  venosus

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Internal Structure of the Frogs Heart and Its
Branches

• e. Ventricle
• ? large thick walled chamber
• f. Muscular Pockets
• ? located at the inner wall of the ventricle
• g. Atrioventricular apertures
• ? connects the atria and ventricle
• ? serves as entrance of blood to the ventricle
• ? guarded by valves which prevent back-flow of
  blood
• h. Septa
• ? two longitudinal division within truncus
  arteriosus
• divides truncus into three channels

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Parts 1.Spiral valve 2. Right atrium 3. Left
atrium 4. Ventricle 5. Truncus arteriosus 6.
Pulmocutaneous arch 7. Systemic arch 8. Carotid
arch
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Internal Anatomy of the Mammalian Heart

• a. ventricles
• constitute the bulk of the heart
• thick walled and highly muscular
• b. apex
• ? posterior narrow portion
• c. base
• ? broad anterior portion
• d. atria
• ? anterior to the base
• thin-walled and dark colored
• right atrium- bigger
• left atrium- smaller
• ? where pulmonary v. enters

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Internal Anatomy of the Mammalian Heart

• e. Interatrial septum
• ? separates right from left atrium
• f. Sinus venosus
• ? in adults is incorporated into this region as
  Sinoatrial node (SA)
• g. Interventricular septum
• ? completely partitions the ventricles
• right ventricle
• ? is smaller and thinner walled
• left ventricle
• ? includes the apex
• ?bigger and thicker walled

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Internal Anatomy of the Mammalian Heart

• h. right atrio-ventricular aperture
• opening between the right atrium and right
  ventricle
• guarded by three membranous flaps or TRICUSPID
  VALVES
• i. left atrio-ventricular aperture
• opening between the left atrium and left
  ventricle
• guarded by two membranous flaps or BICUSPID
  VALVES or MITRAL VALVE
• j. trabeculae carne
• ? muscular ridges that deeply cleave the inner
  walls of the ventricles
• k. papillary muscles
• pointed finger-like muscles
• project from the walls of the ventricles

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Internal Anatomy of the Mammalian Heart

• l. chordae tendinae
• fine thread-like fibers connecting the free edges
  of the tricuspid and bicuspid valves to the tip
  of the papillary muscles
• m. pulmonary artery
• ? opening in the right ventricles where the blood
  leaves
• n. semilunar valves
• guards the exists of the right ventricle to the
  aorta
• guards the exists of the left ventricle to the
  pulmonary arteries

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NERVOUS SYSTEM AND SENSORY ORGANS
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Types of Nervous Systems

• 1. Diffuse type or nerve net
• Simplest type of N.S.
• Found in Coelenterates (Hydra)
• Termed nerve net because it consists of a network
  of nerve cells, each with a number of processes
  radiating from the cell body in all directions
• The processes of neighboring nerve cells connects
  to one another to form a continuous network.
• Called diffuse type because primitive nerve cells
  (neuries or protoneurons) ? non-polar nerve
  impulses are conducted in all directions from
  point of stimulation, no definite pathways
• In higher types of nerve cells, nerve impulses
  travel in one direction only (cell body ? axon)
• Main distinguishable characteristic Lack of
  centralization or absence of concentrations of
  nerve cell bodies at certain areas of the body of
  the animal.

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Types of Nervous Systems

• 2. Ladder type
• Dugesia (flatworm)
• Has cephalization ? head region
• Parts
• Cerebral ganglia ? primitive brain formed from
  aggregation of nerve cells
• Longitudinal nerve cords ? lie parallel to each
  other and pass posteriorly along most of the
  entire length of the body
• Transverse nerves ? rung-like structures of a
  ladder that connect longitudinal nerves into a
  linear seriesn hence the term ladder type of
  nervous system
• Lateral nerves ? innervate the body wall and
  other structures, arises from transverse nerves

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Types of Nervous Systems

• 3. Ganglionic type
• Found in Annelids and arthropods
• Consists of
• Dorsal Brain (Cerebral ganglia)
• located in the head
• B. Ventral Nerve Cord
• extends from the brain posteriorly along the
  length of the rest of the body
• Consists of a segmental series of paired, closely
  approximated ganglia which are connected by two
  longitudinal nerves strands
• C. Longitudinal nerve strands
• forms double chain of ganglia
• Arthropods
• N.S. is more centralized and has fewer ganglia
  due to migration and fusion in the thorax and
  abdomen.
• Longitudinal nerve strands tend to fuse into a
  single strand.

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Types of Nervous Systems

• 4. Tubular typeFound in vertebratesTubular
  vertebrate brain and spinal cord are
  hollow.Brain cavities, termed ventricles, are
  continued with the central canal of the spinal
  cord.

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Types of Nervous System
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Overall Organization of the Vertebrate N.S.

• composed of
• central nervous system
• ? includes the brain and the spinal cord
• ? serves as a central exchange or switchboard
• 2. peripheral nervous system
• ? consists of nerve cells and nerve fibers which
  connect to the C.N.S. to all parts of the body
• 3. the sense organs

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Peripheral Nervous System

• subdivided into the
• Somatic N. S.
• innervates skeletal muscles, skin, and certain
  other body parts
• responsible for movement of various parts of the
  body thru reflex actions and conscious control of
  will
• Autonomic/Visceral N.S.
• innervates cardiac muscles, smooth muscles, and
  glands
• governs and controls the functions of the viscera
  (heart, digestive tract, glands, etc)
• carried out automatically and controlled at the
  unconscious level
• Includes the
• Sympathetic N.S.
• Parasympathetic N.S.
• Both have antagonistic effects

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Autonomic Nervous System

• It consists of the cranial nerves and spinal
  nerves from the spinal cord.
• Frog 10 pairs
• Man 12 pairs
• Spinal nerves
• consist of
• a. Sensory/Afferent
• Transmit impulses from the receptors to the
  C.N.S.
• b. Motor efferent
• Transmit impulses from the C.N.S. to the effectors

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Spinal Nerves

• 1st to 9th Spinal Nerve exit through the
  intervertebral foramina
• 10th gets out through the lateral foramina at the
  anterior third of the urostyle
• Glands of Swammerdam or Periganglionic glands
  masses of white calcareous materials found at the
  sites of the exit of the nerves.

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Spinal Nerves

• Spinal nerves
• 1st connect with larger 2nd spinal nerve to
  form Brachial plexus
• 2nd largest of the first three spinal nerves
  and connects with them to form Brachial plexus
• - main trunk extends to the forelimb as the
  brachial nerve
• 3rd - connect with the larger 2nd Spinal Nerve
  to form the Brachial Plexus. Plexus- a network
  of communicating nerve fibers
• 4th - extend postero-laterally do not form a
  plexus.
• 5th - extend postero-laterally do not form a
  plexus.
• 6th - extend postero-laterally do not form a
  plexus
• 7th - are sharply directed posteriorly and goes
  along with the 8th and 9th spinal nerve to form
  the lumbo-sacral or sciatic plexus.
• 8th - Joins with the 9th to form the Sciatic
  Nerve
• 9th - Joins with the 8th to form the Sciatic
  Nerve
• 10th - lies close to the side of the Urostyle
  (hard to see)

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Autonomic Nervous System

• consists of 2 delicate chains of ganglia
• (Sympathetic Trunk) and several unpaired ganglia
• a. Sympathetic Trunk
• originate from the cranial cavity
• lie alongside the systemic arch and dorsal aorta
• b. Jugular foramina
• located lateral to the occipital condyles
• c. Sympathetic ganglia
• node like structures found at varying intervals
  along the trunks
• d. Rami communicantes or Visceral rami
• connected to the sympathetic ganglia
• P.N.S. does not form an orderly chain of
  ganglia and need not be dissected.

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Central Nervous System

• The brain and the spinal cord are enveloped by
  two meninges or membrane
• Outer pigmented Dura Matter
• Pia Matter
• Both inseparately adhere to the nervous tissue.
• Subdural Space ? in between the 2 filled with
  cerebrospinal fluid

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Parts of the Frog Brain

• 1. Telencephalon or cerebral hemispheres
• ? Enlarged elongated bodies separated medially by
  a groove, found at the anterior part of the brain
• ? Found here are complex centers of consciousness
  and sensations
• 2. Olfactory bulbs
• 3. Telencephalon
• where the first pair of cranial nerves, the
  olfactory nerves originate.
• 4. Olfactory nerves first pair of cranial
  nerves
• 5. Diencephalons (thalamencephalon or twixtbrain
• depressed unpaired lobe posterior to the
  Telencephalon
• The relay center for sensory impulses centers of
  regulating body temperature, water balance
  carbohydrate and fat metabolism
• 6. Anterior Choroid Plexus
• thin membrane that acts as the roof of
  dicencephalon
• 7. Pineal body or epiphysis
• arising from the median dorsal surface of the
  diencephalon
• has an endocrine function

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Parts of the Frog Brain

• 8. Mesencephalon or optic lobes
• a pair of rounded bodies posterior to the
  diencephalons
• where visual and auditory reflex centers are
  located.
• 9. Metencephalon or cerebellum
• the narrow fold posterior to the mesencepahlon
• Responsible for muscle coordination and
  proprioception
• 10. Myelencephalon or medulla oblongata
• Triangular portion posterior to the
  metencephalon. Its broad anterior portion is
  partly covered dorsally by the metencephalon,
  while its tapered portion is continuous with the
  spinal cord
• Located in the various areas of the medulla
  oblongata are the reflex centers that control
  respiration, heart rate, dilation and
  constriction of blood vessels and swallowing.
• 11. Fourth ventricle
• ? The triangular cavity of the which is covered
  by a thin highly vascular membrane
• 12. Posterior choroids plexus
• thin highly vascular membrane covering fourth
  ventricle

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Parts of the Frog Brain

• 12. Filum terminale
• tapering posterior portion where the spinal cord
  extends from the myelencephalon
• occupies the cavity of the urostyle
• 13. dorsal median sulcus
• groove that extends along the median region of
  the spinal cord
• 14. Ventral median fissure
• the corresponding ventral groove of the Dorsal
  median sulcus

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Parts of the Frog Brain

• Ventral Aspect
• 15. Optic chiasma
• ? ventral side of the dicencephalon
• formed by the crossing of the fibers of the
  second pair of cranial nerves
• 16. Optic nerves
• the second pair of cranial nerves
• 17. Infundibulum
• bilobed extension of the diencephalons, posterior
  to the optic chiasma
• 18. Hypophysis or pituitary body
• a small round gland attached to the
  postero-ventral side of the infundibulum, which
  lies on a depression on the floor of the skull
• The hypophysis has endocrine functions regulated
  by neurosecretions produced in the diencephalons
• 19. Sella tursica
• ? depression on the floor of the skull

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Parts of the Frog Brain

• Ventricles of the brain
• 1. first and second lateral ventricles
• cavity of the cerebral hemispheres
• communicate with the cavity of the olfactory
  bulbs
• 2. rhincoeles
• cavity of the olfactory bulbs
• 3. third ventricle
• communicates with the lateral ventricles through
  narrow opening
• foramen of Monro
• 4. Foramen of Monro
• narrow opening of the third ventricle

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Parts of the Frog Brain

• Ventricles of the brain
• 5. optic ventricles or opticoeles
• expanded cavities in the mesencecephalon
• 6. Iter or aqueduct of Sylvus
• narrow cannal where the third and optic
  ventricles connect with forth ventricle
• 7. Fourth ventricle
• continous posteriorly with the cavity of the
  spinal cord
• 8. Central canal or canalis centralis
• cavity of the spinal cord

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F R O G B R A I N
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Sense Organs

• The Eyes
• 1. Sclerotic coat
• the outermost coat of the eye
• Tough, opaque, protective structure that
  maintains the shape of the eyeball.
• 2. Cornea
• anterior portion of the sclerotic coat
• 3. Conjuctiva
• thin, transparent membrane covering the outer
  surface of the cornea and continuous with the
  inner surface of the eyelids
• 4. Optic Nerve
• White, thread-like structure that can be observed
  at the posterior part of the eyeball.
• 5. Retractor bulbi
• muscles attached to the sclerotic coat around the
  optic nerve which pulls the eye into the orbit
• Six other muscles are attached to the eyeball
  at different anges are responsible for other eye
  movement.

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Sense Organs

• The Ear
• Sense organs of hearing and equilibrium
• Frogs ear is composed of two parts
• Middle ear
• external tympanic membrane
• columella
• rod-like bone located inside the tympanic cavity
• extends across the tympanic cavity to the wall of
  the skull.
• 3. Eustachian tube
• where tympanic cavity connects with buccal cavity
• Inner ear

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