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DIGESTIVE SYSTEM

DIGESTIVE SYSTEM. Oral cavity & salivary glands Originally given BY: Dr. ALI ALTIB Done and typed by: د. شموخ Edited & made up 2 date by: Abo Malek Thanks for: Dr.Abdullah. Digestive System. Consists of : Oral cavity ( mouth cavity ). Alimentary tract. Glands. THE ORAL Mucosa.

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DIGESTIVE SYSTEM

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  1. DIGESTIVE SYSTEM Oral cavity & salivary glands Originally given BY:Dr. ALI ALTIB Done and typed by: د. شموخ Edited & made up 2 date by: Abo Malek Thanks for: Dr.Abdullah

  2. Digestive System Consists of : Oral cavity ( mouth cavity ). Alimentary tract. Glands.

  3. THE ORAL Mucosa The oral mucosa consists of stratified squamous epithelium & loose CT (lamina propria ) The epithelium is nonkeratinized stratified squamous except for the dorsal surface of the tongue & the hard palate which are lined by keratinized epithelium.

  4. The Lip The lip is covered externally by keratinized stratified squamous epithelium & internally by nonkeratinized stratified squamous epithelium The lip also contains skeletal muscle, CT, adipose tissue, mucous & serous salivary glands

  5. THE TONGUE The anterior 2/3of dorsal surface is keratinized stratified squamous projections called papillae. The posterior 1/3 & the ventral surface are covered by nonkeratinized epithelium. The tongue contains longitudinal transverse & vertical skeletal muscle, adipose tissue, CT, mucous & serous salivary gland

  6. Tongue: Taste buds • The epithelium of the dorsal surface of the tongue contains oval structures called taste buds • Taste buds are receptors containing cells & sensory nerve endings • A taste bud has a small opening on the surface of the epithelium called taste pore

  7. Cells of the taste buds • Taste buds contain 3 types of cells: • Neuroepithelial cells (taste cells) • Supporting cells • Basal Cells (regenerative cells)

  8. Papillae of the tongue • The mucosa of he anterior 2/3 of dorsal surface forms structures called lingual papillae. • The mucosa of the posterior 1/3 has no papillae but contains lingual tonsils (lymphoid tissue)

  9. TONGUE: Lingual Papillae Four types: Filiform papillae. Fungiform papillae. Circumvallate papillae. Foliate papillae

  10. Filiform papillae Most numerous, covering all the anterior 2/3 of dorsal surface of the tongue. Sharp projections of the keratinizedepithelium. Do not contain taste buds

  11. Fungiform Papillae Found between the filiform papillae Circular in shape & less than filiform papillae Consist of CT covered by nonkeratinized epithelium containing taste buds

  12. Circumvallate Papillae About 8-12 papillae just anterior to the sulcus terminalis Consist of CT covered by nonkeratinized epithelium with taste buds in the sides of the papilla Large & circular in shape, seperated by a deep space from the surrounding epithelium Serous glands (von Ebners glands) secrete into the space surrounding the papilla

  13. Foliate papillae On the posterior lateral border of the tongue. Parallel folds of nonkeratinized epithelium & CT. Contain taste buds in the child Serous glands in the CT under the papilla

  14. Salivary glands Secrete saliva which is carried by ducts to the oral cavity The secretory unit of salivary glands is calledacinus (alveolus) Produce & secrete saliva into the oral cavity. Salivary glands may contain:- Serous acini (secrete thin watery saliva) Mucous acini (secrete mucus) Mixed acini (mucoserous)

  15. Serous acinus Consists of serous cells with basal rounded nuclei & apical granules containing the protein amylase (cytoplasm has a deep staining with H&E)

  16. Mucous acinus • Consists of mucous cells with basal flattened nuclei & apical granules containing the glycoprotein mucin (cytoplasm has a light staining with H&E)

  17. Mucoserous (mixed) • Contain separate serous & mucous acini & their secretion is mixed in the ducts • A mucous acinus may have serous cells on its surface & they are called serous demilunes

  18. Myoepithelial cells (basket cells) • The myoepithelial cells have cytoplasmic processes surrounding the osinus • Contraction of myoepithelial cells presses the acinus & moves the saliva into the ducts

  19. Types Of Salivary Glands Two types according to location:- Minor salivary glands: in oral mucosa (e.g. lip & tongue) Major salivary glands outside the oral cavity: Parotid gland(serous) Submandibular(mixed but mostly serous) Sublingual(mixed but mostly mucous) They are divided into lobules by CT septa

  20. The Ducts Of Salivary Glands Intralobular ducts: The acinus opens into intercalated duct lined by simple cuboidal epithelium. Intercalated ducts join to form striated ducts lined by simple columnar cells with basal folding & numerous elongated mitochondria Interlobular ducts lined by two layers of columnar cells

  21. Structure Of Tooth Contains 3 clacified avascularparts:- Enamel: hard inorganic white substance Dentin: calcified collagen Cementum: similar to bone

  22. Structure of The Tooth The tooth consists of:- The CROWN: projects into the oral cavity & consist of dentin covered by enamel The ROOT is inside the bone & consists of dentin covered by cementum The root is attached to the bone by the periodontal ligament (type I collagen)

  23. The Tooth • Cells called ameloblasts produce enamel & die before eruption, so enamel cannot regenerate • Cells called odontoblasts produce dentin • Cells called cementoblasts produce cementum • The center of the dentin shows CT called pulp containing odontoblasts, blood vessels & nerves

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