Nerve net on right found in the two plexi

• General FunctionsGeneral FunctionsIntracellular vs Extracellular Intracellular vs Extracellular DigestionDigestionGastrointestinal Tract - two wayGastrointestinal Tract - two wayAlimentary Canals - Linear Alimentary Canals - Linear specializationspecializationMechanical and Chemical Mechanical and Chemical DigestionDigestionDigestive organs vs Accessory Digestive organs vs Accessory organsorgans

Basic Structural Basic Structural PlanPlanMucosaMucosaEpitheliumEpitheliumLamina propriaLamina propriaMuscularis mucosaMuscularis mucosaSubmucosaSubmucosaPlexus of MeissnerPlexus of MeissnerPlexus of AuerbachPlexus of AuerbachMuscularis ExternaMuscularis ExternaSerosa or Serosa or AdventitiaAdventitia

Basic Structural PlanBasic Structural PlanMucosaMucosa

EpitheliumEpitheliumLamina propriaLamina propriaMuscularis mucosaMuscularis mucosa

SubmucosaSubmucosaPlexus of MeissnerPlexus of MeissnerPlexus of AuerbachPlexus of AuerbachMuscularis ExternaMuscularis ExternaSerosa or AdventitiaSerosa or Adventitia

Nerve net on right found in the two plexi

No matter what part of the digestive tube, the plan is fundamentally identical with areas specialized for particular functions as needed. Folding increases surface area, glands changes secretions, and muscle enlargement for mechanical controls including sphincters.

This is a longitudinal section through the esophagus. Only part with stratified squamous epithelium (except for anus)

MouthMouthLipsLipsBuccal WallBuccal WallGingivaGingivaTongueTonguePalate - Soft and HardPalate - Soft and HardOropharynxOropharynxBuccal cavityBuccal cavity

• Lips - Red Free marginLips - Red Free margin• Labial frenulum - Labial frenulum -

Inferior & SuperiorInferior & Superior• Lingual frenulumLingual frenulum• Gingiva and Alveolar Gingiva and Alveolar

processes and socketsprocesses and sockets• DentationDentation

Milk or baby teethMilk or baby teethAdult teethAdult teethAnother set?Another set?

• Tooth types - Tooth types - modified for modified for functionsfunctions

• Crown and RootCrown and Root• Incisors – CuttingIncisors – Cutting• Canines or Cuspids – Canines or Cuspids –

GraspingGrasping• Premolar or Bicuspid Premolar or Bicuspid

– Grinding– Grinding• Molar - GrindingMolar - Grinding

CrownCrownEnamelEnamelDentine - Dentine -

Tome’s fibersTome’s fibersNeck - cervixNeck - cervixRootRoot

Pulp cavityPulp cavityDentinDentinCementumCementum

Apical foramenApical foramenPeridontal ligamentPeridontal ligament

CrownCrown Enamel Enamel Dentine - Tome’s fibers Dentine - Tome’s fibers Neck - cervix Neck - cervixRootRoot Pulp cavity Pulp cavity Dentin Dentin Cementum CementumApical foramenApical foramenPeridontal ligamentPeridontal ligament

Tongue Tongue structurestructureSensory ZonesSensory ZonesPapillaePapillaeFiliformFiliformFungiformFungiformCircumvalateCircumvalate

• Thyroglossal Duct remnant

• Terminal Sulcus• Vallate Papillae• Foliate Papillae• Fungiform

Papillae • Median Sulcus • Filiform Papillae

Food coloring on tongue shows the distribution of fungiform papillae

IntrinsicIntrinsic

ExtrinsicExtrinsic

Parotid - Stensen’s ductParotid - Stensen’s ductSerousSerousWaterWaterElectrolytesElectrolytesAmylaseAmylaseNo mucinNo mucinSubmaxillary orSubmaxillary orSubmandibular - MixedSubmandibular - MixedSublinginaLSublinginaLMucusMucusno enzymeno enzyme

Composition of SalivaComposition of SalivaWater - 99.5%Water - 99.5%Electrolytes- Na, Cl, K, Electrolytes- Na, Cl, K, Blood typing proteinsBlood typing proteinsMucin forms mucus; lubricantMucin forms mucus; lubricantUreaUreaImmunoglobin AImmunoglobin ABicarbonates- buffers pHBicarbonates- buffers pHPhosphates - buffers pHPhosphates - buffers pHAmylase - activated by chloride ionsAmylase - activated by chloride ions

Lubrication and bindingLubrication and bindingSolubilizes dry foodSolubilizes dry foodOral HygieneOral Hygiene

Oral cavity flushed with salivaOral cavity flushed with salivaBacteria grow during sleep - Dragon breathBacteria grow during sleep - Dragon breathSaliva contains lysozymes to kill bacteriaSaliva contains lysozymes to kill bacteria

Initiates starch digestion - limitedInitiates starch digestion - limited

Approximately 18 inchesApproximately 18 inchesCollasped tube no sphinctersCollasped tube no sphinctersEsophageal mucus glandsEsophageal mucus glandsNo digestionNo digestionDeglutitionDeglutition

Voluntary Oral PhaseVoluntary Oral PhaseInvoluntary Pharyneal PhaseInvoluntary Pharyneal PhaseInvoluntary Esophageal PhaseInvoluntary Esophageal Phase

Peritoneum - SomaticPeritoneum - SomaticPeritoneum - VisceralPeritoneum - VisceralAbdominal cavity Abdominal cavity Intra-peritoneal organsIntra-peritoneal organsRetroperitoneal organsRetroperitoneal organsMesentaryMesentaryThe MesentaryThe MesentaryMesocolonMesocolonGreater OmentumGreater OmentumLesser OmentumLesser Omentum

Greater Greater Omentum Omentum Lessor Lessor OmentumOmentum