Lect 5 Oral cavity

Question 1

oral cavity divisions

Answer 1

vestibule-space bw lips, cheeks and teeth

oral cavity proper - hard and soft palate, tongue and floor of mouth, entrance to oropharynx

Question 2

Functions

Answer 2

porpulsion
initiation of digestion
protection
sensation (taste buds, reflexes, temp, touch)
secretion - saliva (major and minor glands), sebaceous glands secrete sebum

Question 3

Protection of oral cavity

Answer 3

oral mucosa separates and protects deeper tissues
prevents microorganisms from gaining access to underlying tissues
Tonsils: immunological protection
Forms impermeable barrier (except floor of mouth)
Permeability barrier consists of lipids derived from the membrane – coating granules released into the intercellular space

Question 4

order of layers of oral mucosa

Answer 4

Epithelium -> CT (both make up lamina propria) -> submucosa -> bone

Question 5

organization of oral mucoperioseum

Answer 5

epithelium ->lamina propria -> periosteum->bone

gingiva and parts of hard palate, forms a firm inelastic attachement

Question 6

organization of oral mucosa

Answer 6

2 main components - epithelium and CT
not all regions have a submucosa layer 
**no muscularis mucosae layer in the oral cavity
structural variations based on location
3 types
Masticatory, lining, specialized

Question 7

masticatory mucosa

Answer 7

stratified squamous keratinized or parakeratinized epithelium
lamina propria
covers gingiva, hard palate
injections are painful, infection spreads slowly

Question 8

parakeratinized epithelium

Answer 8

similar to keratinized except that superficial cells do not lose nuclei, cytoplasm does not stain as intensely with eosin

Question 9

Lining mucosa

Answer 9

stratified squamous non keratinized epithelium
covers inner surface of lips, cheeks, soft palate, inferior surface of tongue, floor of the mouth
CT have elastic fibers that control extensibility
Permeability- impermeable except floor of mouth
sublingual medications are readily absorb

Question 10

sprecialized mucosa

Answer 10

dorsal surface of the tongue - taste buds

Question 11

lips

Answer 11

guard passage to oral cavity
3 parts:
cutaneous, vermillion border, oral mucosa

Question 12

cutaneous

Answer 12

outer portion of thin skin (SSKE) with hair follicles and glands

Question 13

vermillion border

Answer 13

dry, red portion covered with thin keratinized skin - NO sweat glands or hair follicles

Question 14

oral mucosa

Answer 14

inner mucous membrane portion, thick lining epithelium (SSNKE)

Question 15

Alveolar mucosa

Answer 15

mucous membrane of the lip reflects back onto the alveolar bone
termed vestibular fold (thin lining mucosa)
-mucosa immediately surrounding an erupted tooth is the gingiva
-mucosa: masticatory

Question 16

Differences of gingiva and labial mucosa

Answer 16

gingiva is tightly bound to bone by dense fibrous CT

lip epithelium is supported by much looser CT

Question 17

Gingiva

Answer 17

oral mucosa surrounding erupted tooth

• gingiva mucosa - faces oral cavity
• junctional epithelium (attachment epithelium): faces tooth - adheres firmly to the enamel/cementum via hemidesmosomes

Question 18

Dentogingival junction

Answer 18

potential weakness in otherwise continuous epithelial lining: potential risk of inflammation
Basal cells rest on a typical basal lamina that interfaces with CT
-most superficial cells provide attachment of the gingiva to the tooth surface by means of epithelial attachment
-consists of an inner basal lamina that adheres to the tooth surface, cells are attached by hemidesmosomes

Question 19

Clinical significance of oral mucosa

Answer 19

CT fibrosis
epithelium - can be affected by a number of pathological conditions
-squamous cell carcinoma
-melanoma
-leukoplakia (white patch of keratinized or parakeratinized epithelium)

Question 20

Tongue

Answer 20

Striated muscle lined with mucous membrane

muscle fibers arranged in three planes results in precise movements

Question 21

dorsal surface of tongue

Answer 21

specialized epithelium
divided into anterior two thirds (body), posterior one third (root)
mucosal irregularities/elevations called lingual papilla (foliate, fungiform, filiform, valate papillae)

Question 22

ventral surface

Answer 22

lining mucosa

Question 23

Four types of papillae

Answer 23

Filiform, foliate, fungiform, circumvallate/vallate

Question 24

Filiform papillae

Answer 24

smallest and most numerous
taste buds not associated w. this epithelium
structure: conical projections of CT covered with highly keratinizes SS epithelium
function: forms tough abrasive surface for a mechanical role
location: distributed across entire dorsal surface of the tonge

Question 25

foliate papillae

Answer 25

deep, mucosal clefts on lateral aspect of the tongue

contain many taste buds in younger individuals, poorly developed in adults

Question 26

fungiform papillae

Answer 26

mushroom shaped projections scattered on dorsal surface
more numerous at tip of tongue
numerous taste buds

Question 27

Circumvallate papilla

Answer 27

large dome shaped structures located just anterior to sulcus terminalis
8-12 in human tongue
surrounded by a moat like invagination lined with multiple taste buds
von ebner’s glands produce a purely serous product into the moat (fluid washes away old taste stimulation to enhance taste of new stimuli)

Question 28

Taste buds

Answer 28

specialized clusters of epithelial cells (50-90 fusiform shaped cells - narrow apical ends converge to form a taste pore
3 types: neuroepithelial cell (sensory), supporting cells, basal cells

Question 29

neuroepithelial cells

Answer 29

aka sensory cells
microvilli that have receptor to interact with tastant, extends from apical cell through the taste pore
form synapse with afferent sensory neuron
cell turnover 7-10 days

Question 30

supporting cell

Answer 30

microvilli on apical aspect

do not synapse with nerve cells

Question 31

basal cells

Answer 31

small cells

stem cell for both neuroepithelial and supporting cell

Question 32

salivary glands and saliva

Answer 32

fluid of the oral cavity=saliva
forms first barrier against infection
large volumes produced daily, varies per individual
majority produced by 3 paired major salivary glands
minor salivary glands contribute to total amount of saliva, all are mixed mucous and serous glands EXCEPT von Ebner’s glands

Question 33

Salivary functions

Answer 33

moisten oral mucosa
moisten food - aid in swallowing
stimulates taste buds
buffers contents of oral cavity
tissue repair 
digestion (amylase)
Tooth development and maintenance

Question 34

Salivary gland structure

Answer 34

arises from developing oral cavity epithelium
consists of secretory component and a duct component
lobes of gland subdivided into lobules by CT

Question 35

Acini

Answer 35

blind ended duct that is composed of secretory cells
3 types
serous, mucous, mixed

Question 36

serous acini

Answer 36

only serous cells, protein secretions stored in zymogen granules in the apical aspect of the cell

Question 37

mucous acini

Answer 37

cells contain mucinogen granules

Question 38

mixed acini

Answer 38

both serous and mucous cells, mucous cells appear to have a cap of serous cells called serous demilunes

Question 39

myoepithelial cells

Answer 39

contractile cells w/ numerous processes

location: between the basal plasma membrane of acinar secretory cells and the basal lamina of the epithelium (also in the proximal duct system)
function: aids in transporting the secretory product to the duct portion of the salivon

Question 40

Salivary ducts

Answer 40

intercalated - low cuboidal epi cells
striated - larger cuboidal cells becoming columnar - infoldings of the basal plasma membrane involved in reabsorption of electrolytes form ‘striations’ in histological sections

Question 41

Excretory ducts

Answer 41

larger ducts and ultimately connect w/ oral cavity
travel in CT of gland and form the principle duct portion
epithelium changes as it blends with the epithelium of the oral cavity from simple cuboidal/columnar to pseudo stratified columnar to stratified squamous

Question 42

Duct component summary

Answer 42

mucous/mixed/serous cells -> small intralobular intercalated duct -> striated duct -> interlobular duct -> statified columnar epi -> main duct

Question 43

3 major salivary glands

Answer 43

Parotid, submandibular, sublingual

Question 44

Parotid glands

Answer 44

completely serous with a well developed duct system
enclosed in a tough CT capsule
fatty tissue allows flexibility

Question 45

submandibular glands

Answer 45

mixed, predominant serous acini

duct runs forward to beneath the frenulum of the tongue

Question 46

sublingual glands

Answer 46

mostly mucus secreting glands (serous demilunes present, but rarely serous acini)
multiple ducts (very small) empty to to submandibular duct or floor of the mouth

Question 47

saliva production

Answer 47

net reabsorption of sodium and chloride produce hypotonic, alkaline saliva. rich in potassium and bicarbonate

Question 48

teeth

Answer 48

32 permanent 20 deciduous
begin digestive process
three hard tissue types: enamel dentin cementum

Question 49

enamel

Answer 49

avascular acellular, nonvital
96% inorganic material in form of hydroxyapatite
hardest calcified matrix in body, rods and interrod formation
derived from ectoderm
ameloblasts

Question 50

dentin

Answer 50

less mineralized than enamel
odontoblasts
works with pulp for repair

Question 51

pulp cavity

Answer 51

richly vascularized, soft CT

Question 52

cementum

Answer 52

covers root of tooth, locked to dentin
mineralized similar to bone
avascular
cementoblasts derived from ectomesenchyme

Question 53

Periodontal ligament

Answer 53

located bw cementum and alveolar bone
principal fiber groups of type 1 collage, specifically arranged to absorb and conteract masticatory forces
Ends of principal fibers are embedded in alveous and cementum as Sharpeys fibers
richly vascularized

Question 54

PDL functions

Answer 54

tooth attachment
tooth support- adjust to stress and movement, avoids direct transmission onto bone which would cause resorption
proprioception
Difference from other ligaments- highly vascularized, highly cellular, lots of nerves

collagen fibers have high turnover rate: poor nutrition causes atrophy and teeth can become loose in their sockets