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DIGESTIVE SYSTEM

DIGESTIVE SYSTEM. Assist. Prof. Alev CUMBUL PhD. 22.11.2013. UPPER DIGESTIVE SYSTEM. OBJECTIVES. Oral Cavity Functions of Oral Cavity Mucosa of Oral Cavity. The digestive system consists of alimentary canal and its associated namely salivary glands , pancreas , liver and gall bladder .

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DIGESTIVE SYSTEM

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  1. DIGESTIVE SYSTEM Assist. Prof. Alev CUMBUL PhD. 22.11.2013

  2. UPPER DIGESTIVE SYSTEM

  3. OBJECTIVES • Oral Cavity • Functions of Oral Cavity • Mucosa of Oral Cavity

  4. Thedigestivesystemconsists of alimentarycanalanditsassociatednamelysalivaryglands, pancreas, liverandgallbladder. Oral cavityincludes;mouthanditscontent; lips, cheek, tongue, gingiva, teethandsalivaryglands. The oral cavity has twoparts. Vestibule Oral cavityproper Vestibulconsists of thelips, cheekandteeth. Oral properconsists of thehard andsoftpalatesandthetongue. Ducts of thesalivaryglandsemptyintothe oral cavity. Themajorsalivaryglandsare: Parotidgland Submandibulargland Sublingualgland Minorsalivaryglandssecreteintothecavity. Theyareshortduets. ORAL CAVITY

  5. ORAL CAVITY FUNCTIONS

  6. Masticatorymucosa: Gingiva Hard Palate Epithelium Masticatorymucosa has keratinizedorparakeratinizedstratifiedsquamousepithelium. Parakeratinizedepithelium is similartokeratinizedepithelium. Epithelialcell of stratumcorneum do not loosenucleii Andthiscellscytoplasmdoesn’tintenselywitheosin. Masticatorymucosaepitheliumsimilarto skin epithelium. Exceptstratumspinosum is lacked. Mucosa of Oral Cavity

  7. LaminaPropria Laminapropria is underlineepithelium. Thislayerincludesdeeppapillae Laminapropria is composedlooseconnectivetissue, bloodvesselsandnerves Inadditionlaminapropriacontainssensoryreceptors Somesendbareaxonending (unmyelinatednerve) Someend in Meissner’scorpuscules. Reticularlayer is underlinedeeppapilla. Thelayerconsists dense connectivetissue. Depth andnumber of papillaecontributestotherelativlyimmobility of themasticularymucosa. Thus it is protectedfromfrictionalandshearingstress. Mucosa is firmlyadharenttotheunderlyingbone. Except in someplaces on thehard plate. Inresult of; reticularlayer of laminapropriawithperiost is blended. MASTICATORY MUCOSA

  8. Submucosa Submucosa is locatedbetweenLaminapropriatohard palate. Submucosacontains adiposetissue, anterior mocousglands, posterior Submucosa is continousposteriorsoftpalate Thickcollagenbandsextendfromthemucosatothe bone in thesubmucosalregion MASTICATORY MUCOSA

  9. Mucosa cover the roof of the oral cavity; a. It is keratinized stratified squamous epithelium. b. Has transverse ridges (rugae) c. LaminaPropria & Submucosa is collagen and reticular fibers blend with the periosteum, HARD PALATE

  10. d. Dense network of capillaries, in the propria- sub mucosa, are well developed. e. Glands (salivary); Mucous and serous in the caudal part of the hard palate. HARD PALATE

  11. Thegingivasurroundseachtooth. Gingiva is composed of stratifiedsquamousepitheliumandunder it is withhighpapillae of connectivetissue. Thisconnectivetissue has interlacing (jointolace) bundles of colllagenenousfiberswithrelativelyfewfibroblastsandnumerousbloodcapillaries. A richvascular network immediatelybelowtheepithelium GINGIVA (GUM)

  12. Gingiva, normalThis is a longitudinal section through a tooth and its supportive structures. At the lowest magnification, you can see the periodontal ligament, the alveolar bone, the pulp and some parts of the gingiva. In these series of images, we're going to study the gingiva. At higher magnification you can study all common structures of the gingiva. Closer to the junctional epithelium, you can see a few inflammatory cells. At even higher magnification, the orientation of the periodontal fibers can be seen. GINGIVA (GUM)

  13. It is found On theLips. Alveolarmucosalsurface Floor of theMouth Inferiorsurface of theTongue Softpalate LiningMucosa

  14. Liningmucosacovers Striatedmuscules on lips, cheekandtongue Bone on thealveolarmucosa Glands, softpalate, cheek, inferiorsurface of tongue It has fewerandshorterpapillaesothat it can adjusttothemovement of itsunderlayingmuscules Lining Mucosa

  15. Epithelium Generallyepithelium of mucosallined is nonkeratinized, although in someplaces it may be parakeratonized. Vermillonborderepithelium of thelips is keratinized. Thenonkeratinizedliningepithelium is thickerthankeratinizedepithelium. Thisepitheliumconsists of 3 layers Stratumbasale Stratumspinosum StartumSuperficiales Thecells of mucosalepithelium is smilartotheepithelium of the skin. Thisepitheliumincludeskeratinocytes, Langerhans’ cells, melanocytesandMerckel’scells LiningMucosa

  16. LaminaPropria Itcontainsbloodvesselsandsensoryreceptors. Thesereseptorsarecomposed of sendbareaxonendingandencapsulatedsensoryending. Thesereceptorsarefound in thebasallayers of theepithelium. Twodifferentregion is observed in thehistologicsection Deeppappillae of thealveolarmucosa Shallowpapillae of theliningmucosa Submucosa Submucosaunderlinestheliningmucosaexcept on theinferiorsurface of thetongue. Submucosacontainslargebands of collagenandelasticfibers. Thus it bindesstriatedmuscules. Submucosacontainsmanyminorsalivaryglands on thelips, tongueandcheeks. Occasionalysubmucosaglandsarefound in thesubmucosa but theseglandsaren’tassociatedwith a hairfollicule. Submucosaglandsarevisibletotheeye. TheyarecalledFORDYCE SPOT. Thesubmucosacontainsthelargerblood, nerveandlymphaticvessels. Thedorsalsurface of thetongue is specializedmucosa. Thismucosacontainspapilaeandtastebuds LiningMucosa

  17. The oral cavity is closedanteriorlybyapposition of theupperandlowerlips. Inlipsandcheekcore is composed of striatedmuscleembedded in elasticfibroconnectivetissue. Externally is a covering of skin withhairfollicles, sebaceousglandsandsweatglands. Internally is a mucousmembrane (mucosa) composed of stratifiedsquamousnonkeratinizingepitheliumandlaminapropriawithhighpapillae. THE LIP AND CHEEK

  18. Laminapropria is undertheepithelium. Itcontainsnumeroussensorynerveendingsandbloodcapillaryplexus. Thesubmucosacontainselasticfibersandstriatedmuscle.Elasticfibersservetobindthemucousmembranequitefirmlytothemuscle. Thuspreventingfolds of themucousmembrane. Inadditional, thesubmucosacontainmanysmallandmucoseroussalivary (labial) glands. (Thisglandsexcertoryduct is short) At thelipmargin, theepidermis is modifiedby a highcontent of keratohyalinand a thickstratumlucidumthatmake it moretranslucent. At thisareadermiscontainshighpapillaeandrichvascularplexus. THE LIP AND CHEEK

  19. LIP (Skin)

  20. LIP (VermillionBorder) Theredregion (vermilianborder) It is linedby a parakeratinizatedstratifiedsquamousepithelium

  21. LIP (Mucosa) The oral mucosaregion The oral mucosaregion is continuouswiththemucosa of thecheeksandgums. Thestratifiedsquamousepithelium

  22. Specialized Mucosa • Thismucosa is restrictedtothedorsalsurface of thetongue, where it containspapillaeandtastebuds

  23. Thetongueconsist of a freelymovableportion. Thetongue is a muscular organ. Location: The Oral Cavity It is attachedtothefloor. Thetongueis coveredbymucousmembraneanditsbulkconsist of striatedmuscle fiber andglands. Thestructure is V shaped. 2/3 portion is theanteriorpart. 1/3 portion is theposteriorpart. Functions: humanspeech, digestion andswallowing. Themusclefibersarebothextrinsicandintrinsic. TONGUE

  24. Thisspecialstructure (striatedmusclearrangement) allowsthetonguetomove 360 degree. Such an arrangement is onlyfound in thetongue. Thereforelingualmuscle is easytoidentifyfromothermuscletissues. Variableamounts of adiposetissue is foundamongthemuscles fiber groups. Sulcusterminalisis on thetongue’sdorsalsurface, whichdividestongueintotwoparts. Foramencecum is theapex of the V point. Foramencecum is theremenant of theembryonaldevelopment TONGUE

  25. The Tongue • Theanteriortwothirds of thetongueconsists of a core mas of skeletalmuscleoriented in threedirections: • Longitudinal • Transverse • Oblique • Theposterioronethirddisplaysaggregations of lymphatictissue, thelingualtonsils.

  26. The Tongue • Dorsal surface of thetongue is specialized mucosa • Thismucosa is similar to masticatory but is highly extensible • Ithas unique papillae types and structure . • Thismucous membranes are of two parts • divided by the V-shaped sulcus terminalis • anterior 2/3 • body of the tongue • posterior 1/3 • base • contains the lingual tonsils

  27. Papillae of The Tongue • Thedorsalsurface of thetonguecontainsnumerousmucosalprojectionscalledlingualpapillae. • Eachlingualpapilla is formedby a highlyvascularconnectivetissuecoreandcoveringlayer of stratifiedsquamousepithelium. • Accordingthetheirshape, they can be dividedintofourtypes: • Filiformpapillae (narrowconical) • Fungiformpapillae (mush-room-shaped) • Circumvallatepapillae • Foliatepapillae (leaf-shaped)

  28. Filiform papillae • Theyarethesmallestandmostnumerous in humans. • Theyareconical, elongatedprojections of theconnectivetissue. • Theyarecoveredwithhighlykeratinizedstratifiedsquamousepithelium. • Thisepithelimdoes not containtastebuds. • Filiformpapillaeserveonly a mechanical role. • Theyaredistributedovertheentireanteriordorsalsurface of thetongue. • Theyappearto form rowsthatdivergetotheleftandrightfromthemidlineandthatparallelthearms of thesulcusterminalis.

  29. Fungiform papillae • Theyaremushroom-shapedprojectionslocated on thedorsalsurface of thetongue. • They preject above the filiform papillae. • They are scattered. • They are visible as small spots. • They tend lobe more numerous near the tip of the tongue. • Taste buds are present in the stratified squamous epithelium on the dorsal surface of these papillae. • Their apical surface is not initially keratinized. • The surrounding filiform papillae exhibit heavy keratinization (D) of their tips.

  30. Circumvallate papillae • Theyarewall-likeshaped. • Theyarelocated in theposteriorpart of thetongue, aligned in front of thesulcusterminalis. • Only 8-12 of these papillae is found in humans. • Each papillae is surrounded with stratified squamous epithelium and it contains numerous taste buds. • They contain lingual salivary glands, which are called Van Ebner Glands. • These glands empty serous secretion in to the mouth

  31. Foliate papillae • Theyconsist of parallellowridgesseperatedbydeepmucosalclefts, whicharealigned at rightanglestothelongaxis of thetongue. • Theyoccur on thelateraledge of thetongue. • They may not be recognised in aged humans. • They are easily found on the posterior lateral surface of the tongue. • They contain many taste buds in the epithelium. • Small serous glands empty in to the cleft.

  32. Foliate papilla Circumvallate papilla Fungiform papilla

  33. Taste Buds • Theyare composed of two types of cells, neuroepithelial and supporting (sustentacular) cells. • The neuroepithelial cells communicate with the free surface of the mucosa by the taste canal • Microvilli ("taste hairs") project from the ends of the neuroepithelial cells into the taste canal. • the neuroepithelial cells are usually located centrally in the structure, surrounded by their supporting or sustentacular cells

  34. Tastebudsarealsopresent on theglossopalatinearch, on thesoftpalate, on theposterior of theepiglottisandtheposteriorwall of pharynx (downtothelevel of thecricoidcathage) ThesefibersareoriginatedfromnervesVII, IX and X. Tastebudsonlyreacttothreestimuly Sweet: Fungiform Salty: Foliate Bitter andacid; Circumvallate In general tastebuds at the tip of thetonguedetectsweetstimulyandassociatedwithFungiformpapillae. Thoseimmadiatelyposterolateraltothe tip of thetonguedetectsaltystimulyandassociatedwithFoliatepapillae. Those on thecircumvallatapapillaedetectbitterstimuli. TASTE BUDS

  35. They are located in the lamina propria of the root (base) of the tongue. They are found posterior to the sulcus terminali. The lingual tonsils contain lymphatic nodules with germinal centers. Between nodules, the lingual epithelium has the characteristics of lining epithelium LINGUAL TOSILS

  36. The gingiva surrounds each tooth. Gingiva is composed of stratified squamous epithelium and under it is with high papillae of connective tissue . This connective tissue has interlacing (join to lace) bundles of colllagenenous fibers with relatively few fibroblasts and numerous blood capillaries. GINGIVA (GUM)

  37. Teeth are a major component of the oral cavity and essential for the digestive process. Teeth are embedded in and attached to maxilla and mandible. Although at the beginning there are deciduous tooth, around the age 6 it replace with permanent tooth. Adult tooth consist of 4 distinct structural components The Enamel The Cementum The Dentin The Pulp TEETH AND SUPPORTING TISSUE

  38. Enamel covers the crown of the tooth. Clinical crown is visible above the gum. Anatomical crown is covered by enamel. Enamel layer ends at the cemento-enamel junction. The root of the tooth is then covered by compendium. Enamel is the hardest component of the human body and the richest calcium. Enamel is produced by cells of ectodermic origin. Enamel is 99% inorganic material. It is mainly calciumphosphate in the form of the apatite crystals. Enamel has 1% organic matrix material. This isn't composed of collagen fibrils. ENAMEL

  39. Enamel prism extend from the dentin enamel junction to the tooth surface. Enamel matrix is secreted by cells called ameloblast. This cell is about 6 m in diameter, tall columnar and basically hexagonal. These cell contain numerous mitochondria in the region below the nucleus and rough endoplasmic reticulum and well-developed Golgi complex above the nucleus. This cell apices elongated as Thomes's processes. Also this cell contain numerous secretory granules. These granules contain the protein the proteins that make up the enamel matrix. ENAMEL

  40. Cementum covers of the root of the tooth, from neck to the apex. Cementum serves to attach to the periodontal membrane. Histologically, it is similar to bone, with coarse (indecent, rough in texture) bundles of collagen fibrils in a calcified matrix. However, Haversian systems and blood vessels are usually absent. Cementumnourishments is provided by blood vessels in the surrounding periodontal membane. In general, it is thin and acellullar in the upper third. Bone cells (cementocytes) are present in lower part. The cell lying in lacunae interconnected by canaliculi Collagen bundles are continuous with fibers from the periodontal membrane that penetrate the cementum as Sharpey' s fibers. These don' t calcified thus they appear as clear canals in ground section. CEMENTUM

  41. Increase in thickness, which may develop near the apex in old age occurs, by appositional growth. That is, on surface of the cemented is added new layers. Occasionally, the thickness is such that Haversian system with blood vessels will form. Destruction of selenium occurs rarely (i.e. periodontal membrane disease. Cemented seems more resistant to resumption than bone. Stochastic activity is only seen in root resumption during replacement of the deciduous dentition. CEMENTUM

  42. Dentin lies deep to the enamel and cemented. Dentin is calcified tissue like bone but harder. Because higher content of calcium salts (70-80%) in the form of the hydroxyapatite crystals. The organic intercellular material (20%) is composed mainly of collagen fibers and glycosaminoglycans, The organic matrix of dentin is secreted by Odontoblasts The Odontoblast is a slender polarized cells. This cell produce organic matrix only at the dentinal surface. Odontoblasts lie as a single row of a cells at the periphery of the pulp on the inner aspects of dentin. This cell is origin mesenchymal. Odontoblasts are tall, columnar-like cells with basal nuclei, basophilic cytoplasm with much granular endoplasmic reticule, and large supranuclear Golgi apparatus. Appically, toward the dentin, the cells show a cell web with junctional complexes and long, slender, cytoplasmic processes, called Tomes Dentinal Fibers. DENTIN

  43. Tomes Dentinal Fibers penetrate through the full thickness of the dentin, lying in small canals in the dentin called the Dentinal Tubules. Dentinal tubules are extensively branched near the junction between dentin and enamel. Odontoblast processes have a diameter of 3-4 m near the cell body. But gradually become thinner at their distal ends. This layer essentially is no mineralized and stains differently than does dentin. It is believed that these stimuli are received by the dentinal fibers and transmitted to nerve fibers in the pulp. DENTIN

  44. The pulp of the tooth originates mesenchymal tissue. The dental pulp fills the main pulp chamber and the root canals. It consist of cells and intercellular material. Intercellular material composed of fine collagen fibrils and ground substance. Ground substance contains glycosaminoglycans. The main cell type is stellate and resembles mesenchyme. With summary, the pulp is a loose connectivetissue that is richly vascularized and supplied by abundant nerves. The blood vessel and nerves enter the pulp cavit at the apex of the root. At site called the apical foramen. DENTAL PULP AND PULP CAVITY

  45. The periodontal membrane or ligament is a special type of dense fibrous connective tissue. Periodontal ligament lie between alveolar bone and the tooth. Periodontal membrane supports the gingiva at the neck of the tooth Periodontal ligament provide for Attachment Support Bone remodelling Nutrition of the adjasent structure Proprioception Tooth eruption. PERIODONTAL LIGAMENT

  46. LOCATION: There are three major salivary glands in the mouth. Parotid Gland Submandibular Gland Sublingual Gland The parotid and submandibular gland is actually located outside the oral cavity. The parotid gland is located subcutaneously. It is below and front of the ear. The submandibular gland is located under the floor of the mouth, close to the mandible (this gland is sometimes called submaxillary gland). The sublingual gland is located in the floor of the mouth anterior to the submandibulary gland. SALIVARY GLANDS

  47. There are also numerous minor glands in the oral cavity. The minor salivary glands are located in the submucosa of different parts of the oral cavity. There are Lingual, Labial, Buccal, Molar and Palatine glands. Each salivary gland arises from the developing oral cavity epithelium. The proliferation of the epithelial cells eventually produces highly branched epithelial cords and bulbous ends. The bulbous ends lead to their canalization The cord become the ducts The bulbous end become the secretory acini. SALIVARY GLANDS - LOCATION

  48. CONNECTIVE TISSUE OF MAJOR SALIVARY GLANDS The major salivary glands are surrounded by a capsule. Capsule is moderately denseconnective tissue. Glands are divided by connective tissue. This tissue is called septa.. Septa is divide the secretory portions of glands into lobules and lobes. The septa contain the larger blood vesselsand the excretory ducts. There is no capsule around the minor salivary gland. Numerous lymphocytes and plasma cells populate is surrounded the acini. SALIVARY GLANDS STRUCTURE; STROMA

  49. ACINI STRUCTURE: The acini of salivary glands contain either serous cells (protein-secreting), mucous cells (mucine-secreting) or both serous and mucous cells. This three types of acini are described; Serous acini Mucous acini Mixed acini Serous acinus’s generally spherical Mucous end pieces are usually more tubular. SALIVARY GLANDS STRUCTURE; PARENCHYMA

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