5-Digestive System-I-Oral Cavity

Question 1

Oral cavity parts

Answer 1

• Vestibule(space between lips, cheeks, teeth

- Oral cavity proper( hard & soft palate, tongue nad floor of mouth, entrance o oropharynx)

Question 2

Functions of oral cavity

Answer 2

• 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

Question 3

Oral mucosa types and tissue components

Answer 3

1) Masticatory mucosa
2) Lining mucosa
3) Specialized mucosa
- Epithelium and CT layers
- Sometimes submucosa
- Never muscularis mucosa in oral cavity

Question 4

Masticatory mucosa

Answer 4

• Stratified squamous keratinized or parakeratinized epithelium
• covers gingiva, hard palate
• difficult and painful to inect and infections spread slowly

Question 5

Lining mucosa

Answer 5

• 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

Question 6

Specialized mucosa

Answer 6

Dorsal surface eof the tongue

Question 7

Lips function and parts

Answer 7

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

Question 8

Alveolar mucosa

Answer 8

Mucous memebrane from the lip that is not attached

-reflection is called vestibular(mucolabial) fold

Question 9

Gingiva

Answer 9

• 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

Question 10

Dentinogingival junction

Answer 10

• 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

Question 11

Clinical significance of oral mucosa

Answer 11

• CT can have fibrosis

- Epithelium form squamous cell carcinoma, melanoma, leukoplakia of keritainized or parakeratinized epithelum

Question 12

Tongue

Answer 12

• Striated muscle with mucous membrane
• muscle fibers arranged in 3 planes for precise movements
• Function: speech, propulsion, digestion, swallowing

Question 13

Tongue surfaces

Answer 13

Dorsal surface: Specialized epithelium, anterior 2/3 body and posterior 1/3 is the root, have lingual palilla
Ventral surface: lining mucosa

Question 14

types of papillae

Answer 14

• Filiform papillae
• Foliate paillae
• Fungiform papillae
• circumvallate papillae

Question 15

Filiform papillae

Answer 15

-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

Question 16

Foliate papillae

Answer 16

Deep mucosal clefts

contain many taste buds in younger individuals poorly developed in adults

Question 17

Fungiform papillae

Answer 17

• Mushroom shaped scattered on dorsal surface
• more numerous at tip of tongue
• numerous taste buds

Question 18

Circumvalate papillae

Answer 18

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

Question 19

Taste buds

Answer 19

Specilized clusters of epithelial cells 50-90 fusiform shaped cells in one taste pore.
-neuroepithelial, supporting and basal cells

Question 20

Neuroepithelial cells(sensory cells)

Answer 20

• Microvilli that have receptors extend apically
• form synapse with afferent sensory neurons
• 7-10 day turnover

Question 21

Supporting cells

Answer 21

Microvilli on apical aspect

-do NOT synapse eith nerve cells

Question 22

Basal cells

Answer 22

Stem cells for supporting and neruoepithelial cells

Question 23

Saliva(general)

Answer 23

-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

Question 24

Saliva funtions

Answer 24

• Moisten oral mucosa
• moisten food- aid in swallowing
• stimulate taste buds
• buffers contents of oral cavity
• tissue repair
• digestion(amylase)
• tooth development and maintenance

Question 25

Salivary gland structure

Answer 25

- arise from developing oral cavity epithelium - secretory component and duct component - The blind end duct with secretary cells is the acini

Question 26

Acini types

Answer 26

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

Question 27

myoepithelial cells

Answer 27

Contractile cells that squeeze the acini

Question 28

Salivary duct types

Answer 28

- Intercalated ducts - Striated ducts - Excretory ducts

Question 29

Intercalated ducts

Answer 29

Low cuboidal epithelial cells

Question 30

Striated ducts

Answer 30

Larger cuboidal cells becoming columnar | -infoldings of the basal plasma memebrane(for striations) involved in resorption of electrolytes

Question 31

Excretory ducts

Answer 31

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

Question 32

Major salivary glands(list)

Answer 32

1) Parotid glands 2) Submandibular glands 3) Sublinual glands

Question 33

Parotid gland

Answer 33

- Serous only - enveloped in tough CT capsule - Fatty tissue to allow flexibilty

Question 34

Submandibular gland

Answer 34

- Serous and mucous - Predominantly serous acini - duct runs forward to beneath the frenulum of the tongue

Question 35

Sublingual

Answer 35

- Mucous & serous - Mostly mucous - multiple very small ducts that empty to submandibular duct or the floor of the mouth

Question 36

Saliva modification

Answer 36

Reabsorbs Na+ and Cl- with water not moving. giving a hypotonic alkaline saliva

Question 37

Enamel

Answer 37

``` Acellular avasular nonvital/insensitive tissue 96% inorganic -hardest calcified martix in the body -forms enamel rods -ectoderm derived produced my ameloblast ```

Question 38

Dentin

Answer 38

``` -More mineralized than bone 70% hydroxyapatite -Type I collagen -made by odontoblasts -cells reside in the pulp ```

Question 39

Pulp

Answer 39

Highly vacularized and abundant nerves

Question 40

Cementum

Answer 40

- Covers root of the tooth firmly - Mineralized similar to bone - avascular - ectomesenchyme derived

Question 41

PDL(general)

Answer 41

- 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

Question 42

PDL(function)

Answer 42

- Tooth attachment/fixation - tooth support adjusts to movement and stress - proprioception - detects pain

Question 43

PDL vs other ligaments

Answer 43

- Highly cellular - Rich blood supply - Lost of nerves