Digestive System IOral Cavity & Associated Structures

• Alimentary canal


  Mouth, tongue, teeth, salivary glands, pancreas, liver, gallbladder
• Formation of bolus


  bolus -> pharynx -> esophagus -> stomach -> small intestine (absorption) -> undigested food, mucus, bacteria, desquamated cells, bile pigments -> feces
• Alimentary mucosa


  • Secretion
  • Absorption
  • Barrier
  • Immunologic protection
• Oral cavity


  Mouth, tongue, teeth, salivary glands and tonsils
• oral cavity is vestibule

  a channel, cavity, or chamber that leads into or is an entrance into another body cavity.
• Oral cavity proper


  Part of the oral cavity
• Salivary glands


  • Parotid
  • Submandibular
  • Sublingual
• Tonsils


  Aggregates of lymphatic tissue (palatine, tubal, pharnygeal [adenoid], lingual)
• Masticatory mucosa


  Gingiva and hard palate; keratinized stratified squamous epithelium with underlying loose and dense connective tissue; papillae keep tissue immobile
• Lining mucosa


  Lips, cheeks, inferior tongue, soft palate; covers muscle; fewer papillae; generally nonkeratinized
• Specialized mucosa


  Dorsal surface of the tongue; contains papillae and taste buds
• Tongue


  Muscular organ projecting into the oral cavity; lingual muscles are striated; contains papillae
• Papillae


  • Filiform= mechanical
  • Fungiform=taste buds
  • Circumvallate= accept saliva from lingual glands
  • Foliate= taste buds
• Taste buds


  Found on fungiform, filliate and circumvallate papillae; oval, pale-staining bodies on the epithelium; taste pore = opening onto epithelium; neuroepithelial cells = sensory cells; supporting cells; basal cells = stem cells for the two other cell types; react to sweet, salty, bitter and acid
• Teeth


  Attached to the alveolar processes of the maxilla and mandible; three specialized tissues: enamel, cementum, dentin; enamel = acellular, mineralized tissue that covers the crown of the tooth; cementum = covers the root; dentin = lies deep to the enamel and cementum; pulp = loose connective tissue; vascularized; abundant nerves
• Salivary glands


  Major glands are paired with long ducts that empty into the oral cavity; parotid, submandibular, sublingual; salivon = secretory unit of the gland; bulbous ends of the gland = secretory acini; serous = protein secreting; spherical; mucous acini = mucin secreting; tubular; mixed acini
• Salivary gland types


  • Parotid gland = serous acini
  • Submandibular gland = mixed
  • Sublingual gland = mixed, but mucous dominate
• Saliva


  1200 mL of saliva/day; functions are moistening, provide a medium for dissolved food to stimulate taste buds, buffer oral cavity, digest carbohydrates (b-amylase), control bacterial flora (lysozyme), source of calcium & phosphate, & contains IgA