Histology of the digestive system part1


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Histology of the digestive system part1

  1. 1. - composed of the alimentary canal and the associated glands- the alimentary canal is a long, tortuous tube, which begins with the lips and terminates with the anus
  2. 2. Common properties of the wall of thedigestive tractThe wall is composed of the following layers as follows from the lumen:1. Tunica mucosa ( mucous membrane)2. Tunica submucosa3. Tunica muscularis4. Tunica serosa ( serous membrane) or adventitia
  3. 3. the most inportant layer with various tissuecomponentshas diverse functions: - protection - secretion - absorption
  4. 4. - sublayers of the submucosa: 1./ a. lamina epithelialis - epithelium 1./ b. lamina propria connective tissue proper 1./ c. lamina muscularis mucosae smooth muscle
  5. 5. adluminal, covering epitheliumfunctions: physicochemical barrier between the lumen and the connective tissue selective absorption of the digested substances secretion of digestive enzymes and lubricating mucins
  6. 6. the types of the epithelium reflects thespecial demands of the appropriatesegments of the alimentary canalexamples: oral cavity, esophagus stratified, nonkeratinized squamous epithelium stomach simple columnar epithelium small intestine simple columnar epithelium with cuticle
  7. 7. loose connective tissue, which contains blood -and lymphatic vessels, nerve fibers and differentkinds of connective tissue cellsin the lamina propria of most segments of theG.I.T., there are tubular glands, such as thegastric - and intestinal glandselements of the immune system is presentthroughout the G.I.T. to defend the bodyagainst possible bacterial attacks
  8. 8. thin layer of smooth muscle, which isoften composed of an inner circular andouter longitudinal sublayerscontributes to the motility of the mucousmembrane; this movement is independentof the peristaltic movement of the tract
  9. 9. connective tissue layer with various thickness;here blood vessels runcontains plexus of lymphaticscontains vegetative ganglion cells and peripheralnerves, which together make the submucousplexus of Meisnermay contain glands in the submucosa of certainsegments ( esophagus and duodenum)
  10. 10. relatively thick layer with two sublayers ofsmooth muscle in the vast majority of casesinner circular sublayer ( str. circulare)outer longitudinal sublayer ( str. longitudinale)the sublayers are separated by thin connectivetissue containing the myenteric plexus ofAuerbach as well as blood and lymphatic vessels
  11. 11. there are striated muscles in the proximalsegments of the esophagus, and also in theanal canalthere is a third muscular sublayer in the wall ofthe stomach: inner oblique fibersin the large intestine, the external sublayerforms longitudinal bands of smooth muscletaeniae coli
  12. 12. tunica serosa ( serous membrane) is theoutermost layer of those segments of thealimentary canal that are enveloped byperitoneum has simple squamous epithelium ( lamina epithelialis; mesothelium) and a thin connective tissue sublayer ( lamina propria serosae) the serous membrane is attached to the muscularis through a subserous connective tissue
  13. 13. Tunica advenitia certain segments of the G.I.T. are not enveloped by peritoneum in these segments, the outermost layer is loose connective tissue ( adventitia) , which connects the tract to the its surroundings
  14. 14. salivary glands in the lamina propria mucosaesubmucous glands in the tela submucosaextramural glands ( large digestive glands) arelocated outside the wall of the tract ; theydischarge their products into G.I.T. lumenthrough excretory ducts
  15. 15. characteristic anatomical items: lips teeth tounge salivary glands
  16. 16. border the mouth opening ( oral fissure)there scaffoldings are striated musclefibers of the orbicularis oris m.have cutaneous and mucous surfaces( pars cutanea and pars mucosa)
  17. 17. Pars cutanea - outer surface, which is composed of skin ( epidermis,dermis and hypodermis, which is also called subcutaneous tissue).In this surface, there various derivatives of the skin: hair follicles,sebaceous and sweat glands.Pars mucosa inner surface, which lines the oral cavity. Thissurface is covered by a mucous membrane, containing stratified,nonkeratinized, squamous epithelium and connective tissue. In thelater layer there are small salivary glands: labial glands.Rubor labii - vermilion zone between the ordinary skin and themucous membrane. The vermilion zone is covered by stratified,keratinized, squamous epithelium. This zone is devoid of skinappendages. However, the zone has capillary- rich connective tissuepapillae, the red color of which may be well visible through therelatively thin skin.
  18. 18. The tongue is a muscular organ, covered bymucous membrane. Its main mass is striatedmuscle, fibers of which run in all directions ofspace. This sort of organization is highly typicalof the tongue.The mucous membrane on the superior andinferior surfaces are very much different .On the superior surface ( dorsum of tongue) ,there are lingual papillae.
  19. 19. Behind the sulcus terminalis, there arelymphatic follicles of the lingual tonsil.The mucose membrane of the inferiorsurface is smooth, lacks connectivetissue papillae.
  20. 20. serosus glands of Ebner, which open at thebase of vallate - and foliate papillaemucinous glands in the root of tongueposterior lingual glandsmixed glands in the apex of tongueanterior lingual glands ( gland of Blandin andNuhn)
  21. 21. filiform papillaefungiform papillaefoliata papillaevallatae papillae
  22. 22. they are located in front of the sulcus terminalislarge, roundish lingual papillae with a diameterof 2-3 mm; thus, they can be readily seen withnaked eyesone man has 8-12 vallate papillaehave taste buds in their wallseach papilla is encircled by a moat - like trenchthe Ebner s serous glands empty into the moatsof the papillae
  23. 23. are lightly stained oval bodies, located in thestratified, nonkeratinized, squamous epitheliumof the mucous membranecell types: supporting cells secondary neuroepithelial cells undifferentiated stem cells
  24. 24. Parts crown of tooth neck of tooth root of toothinside the crown and neck, there is a toothpulp, inside the root , there is a root canal,which opens in the apical foramen
  25. 25. Dentin ( substantia eburnea)Enamel ( substantia adamantina,enamelum)Cementum ( substantia ossea, cementum)
  26. 26. inorganic substances: 80% hydroxy- apatite crystalsorganic substances: 20% its 9/ 10: type I collagen its 1/ 10: proteoglycans
  27. 27. Enamelinorganic substances: 98% hydroxy- apatite crystalsorganic substances: 2% insoluble proteinsThere are NO cells within the enamel!
  28. 28. Cementum covers the roots of teeth cementoblasts produce; the resting cells are cementocytes inorganic substances: 50% organic content is mainly made up of collagen fibers the cementum is tethered to the periodontium by Sharpey s fibers
  29. 29. PARODONTIUM Cementum Periodontium connecting tissue membrane, which is rich in fibers; contains blood vessels and nerves. Its cells are fibroblasts, which can be converted either cementoblasts or osteoblasts of alveolar bone. Alveolar bone
  30. 30. loose connecting tissue, which is rich incapillaries and nervescells: fibroblasts, mast cells, macrophages, lymphocytes odontoblasts, which produce the dentin
  31. 31. Small salivary glands labial, buccal, palatine, linguales, etc. glandsLarge salivary glands parotid, submandibular, sublingual glandsAll of them are exocrine glands.
  32. 32. secretory portion can be serous, mucousor mixed / Gianuzzi s demilune/excretory portion intralobular ducts intercalated tubules, striated ducts interlobular ducts excretory ducts
  33. 33. purely serous glandthere are many fat cells among the aciniwell-developed intercalated tubules and salivaryductsin the interlobular septa, run the larger excretoryducts, blood vessels and peripheral nervesthere may be many cross- sections of thebranches of the facial nerve, which pass theparotid
  34. 34. mixed gland, but the mucous secretorycells predominate over the serous ones.the serous cells are located as smallclusters around the mucous acini: theseare Gianuzzi demilumesboth the intercalated tubules and thestriated ducts are usually absent
  35. 35. mixed gland, in which the serous secretorycells predominatethe scattered mucous acini are partlycovered by serous cap / Gianuzzi sdemilune/there are somewhat smaller numberintercalated tubules and striated ductsthan in the parotid