5-Digestive System-I-Oral Cavity Flashcards
Oral cavity parts
- Vestibule(space between lips, cheeks, teeth
- Oral cavity proper( hard & soft palate, tongue nad floor of mouth, entrance o oropharynx)
Functions of oral cavity
- Propulsion
- Initiation of digestion
- Protection( Oral mucosa separates and deeper tissues, prevents microorganisms from going into depper tissue, Tonsils provide immunological protection, forms impermeable barrier)
- Sensation
- Secretion
Oral mucosa types and tissue components
1) Masticatory mucosa
2) Lining mucosa
3) Specialized mucosa
- Epithelium and CT layers
- Sometimes submucosa
- Never muscularis mucosa in oral cavity
Masticatory mucosa
- Stratified squamous keratinized or parakeratinized epithelium
- covers gingiva, hard palate
- difficult and painful to inect and infections spread slowly
Lining mucosa
- Stratified squamous non-keratinized epithelium
- Covers surface of lips, cheeks, soft palate, inferior surface of the tongue, floor of the mouth
- CT layers have elastic fibers
- Impermeable except the floor of the mouth
- easy, minimally painfully injections and infections spread quickly
Specialized mucosa
Dorsal surface eof the tongue
Lips function and parts
guard the passage to the oral cavity
1) cutaneous-skin SSKE with hair follicles and glands
2) Vermillion border- dry, red portion covered with thin keratinized skin, NOsweatglands ot hair follicles
3) Oral mucosa- inner mucous memebrane. Thick lining epithelium SSNKE
Alveolar mucosa
Mucous memebrane from the lip that is not attached
-reflection is called vestibular(mucolabial) fold
Gingiva
- Oral mucosa surrounding an erupted tooth
- Is tightly attached to the alveolar bone by dense fibrous CT
- Gingival mucosa-faces oral cavity
- Junctional epithelium(attachment epithelium) faces the tooth
Dentinogingival junction
- potential risk in inflammation
- basal cells rest at the typical basal lamina (outer,external) that interfaces with connective tissue
- inner basal lamina adheres to the tooth surface, cells are attached by hemidesmosomes
Clinical significance of oral mucosa
- CT can have fibrosis
- Epithelium form squamous cell carcinoma, melanoma, leukoplakia of keritainized or parakeratinized epithelum
Tongue
- Striated muscle with mucous membrane
- muscle fibers arranged in 3 planes for precise movements
- Function: speech, propulsion, digestion, swallowing
Tongue surfaces
Dorsal surface: Specialized epithelium, anterior 2/3 body and posterior 1/3 is the root, have lingual palilla
Ventral surface: lining mucosa
types of papillae
- Filiform papillae
- Foliate paillae
- Fungiform papillae
- circumvallate papillae
Filiform papillae
-Smallest most numerous
-no taste buds
-Structure:conical projections of connective tissue covered with highly keratinized SSE
-Function: forms and an abrasive surface for mechanical role
Location: all over tongue
Foliate papillae
Deep mucosal clefts
contain many taste buds in younger individuals poorly developed in adults
Fungiform papillae
- Mushroom shaped scattered on dorsal surface
- more numerous at tip of tongue
- numerous taste buds
Circumvalate papillae
Large domed shaped located anterior to sulcus terminals
- 8-12 on a tongue
- surounded by moat like invaginations, multiple taste buds
- Von Ebners glands produce serous product in the moat washes old taste
Taste buds
Specilized clusters of epithelial cells 50-90 fusiform shaped cells in one taste pore.
-neuroepithelial, supporting and basal cells
Neuroepithelial cells(sensory cells)
- Microvilli that have receptors extend apically
- form synapse with afferent sensory neurons
- 7-10 day turnover
Supporting cells
Microvilli on apical aspect
-do NOT synapse eith nerve cells
Basal cells
Stem cells for supporting and neruoepithelial cells
Saliva(general)
-fluid of the oral cavity
-First barrier again infection
-aids in speech and swallowing
-majority is made by 3 major glands
all are mixed mucous and serous except Von Ebner’s
Saliva funtions
- Moisten oral mucosa
- moisten food- aid in swallowing
- stimulate taste buds
- buffers contents of oral cavity
- tissue repair
- digestion(amylase)
- tooth development and maintenance
Salivary gland structure
- arise from developing oral cavity epithelium
- secretory component and duct component
- The blind end duct with secretary cells is the acini
Acini types
1) Serous- only serous cells protein secretion from zymogen granules
2) mucous acini- cells contain mucinogen granules
3) Mixed acini both serous and mucous- Mucous cells appear to have a cap of serous cells called serous demilunes
myoepithelial cells
Contractile cells that squeeze the acini
Salivary duct types
- Intercalated ducts
- Striated ducts
- Excretory ducts
Intercalated ducts
Low cuboidal epithelial cells
Striated ducts
Larger cuboidal cells becoming columnar
-infoldings of the basal plasma memebrane(for striations) involved in resorption of electrolytes
Excretory ducts
Larger ducts that go to the oral cavity
Travel in the CT of the gland
-epithelium changes as it goes to the oral cavity from simple cuboidal/columnar to psuedostratified columnar to stratified squamous
Major salivary glands(list)
1) Parotid glands
2) Submandibular glands
3) Sublinual glands
Parotid gland
- Serous only
- enveloped in tough CT capsule
- Fatty tissue to allow flexibilty
Submandibular gland
- Serous and mucous
- Predominantly serous acini
- duct runs forward to beneath the frenulum of the tongue
Sublingual
- Mucous & serous
- Mostly mucous
- multiple very small ducts that empty to submandibular duct or the floor of the mouth
Saliva modification
Reabsorbs Na+ and Cl- with water not moving. giving a hypotonic alkaline saliva
Enamel
Acellular avasular nonvital/insensitive tissue 96% inorganic -hardest calcified martix in the body -forms enamel rods -ectoderm derived produced my ameloblast
Dentin
-More mineralized than bone 70% hydroxyapatite -Type I collagen -made by odontoblasts -cells reside in the pulp
Pulp
Highly vacularized and abundant nerves
Cementum
- Covers root of the tooth firmly
- Mineralized similar to bone
- avascular
- ectomesenchyme derived
PDL(general)
- between cementum and alveolar bone
- primary fiber group made of type I collagen
- high collagen fiber turnover
- End are embedded into cementum as Sharpey’s fibers
- Highly vascularized
PDL(function)
- Tooth attachment/fixation
- tooth support adjusts to movement and stress
- proprioception
- detects pain
PDL vs other ligaments
- Highly cellular
- Rich blood supply
- Lost of nerves
