Oral Structures Flashcards
Function of Oral Cavity
- Gateway to digestive system
- Speech
Secondary Functions:
Respiration, Defense
Spaces
- Vestibule
- Oral Cavity Proper
- Pharynx
Characteristics of External Surface
- Keratinized Stratified Squamous Epithelium (skin)
2. Hair and Sweat Glads
Characteristics of Vermillion Zone (red area of lips)
- Transition between keratinized and non-keratinized
- Abundant dermal capillaries (red)
- No hair or sweat glands
Characteristics of Internal Surface
- Typical oral mucosa
2. Mucosa tethered to underlying muscle at intervals in many folds
Number of permanent Teeth
32 permanent teeth and 8 within each dental quadrant
Incisors
8 teeth for cutting, single root
Canine
4 teeth for grasping, single root
Premolars
8 for grinding, two roots
Molars
12 for grinding, 2/3 roots
Permanent teeth are preceded by…
20 deciduous (baby) teeth– No deciduous precursors for the molars
2 Main Regions of Tooth Structure
A. Crown (exposed)
B. Root (in socket)
(both meet at neck)
What is Enamel
99% calcium crystals
-Hardest substance in body
What is Dentin
Bulk of the tooth (bone-like but harder than bone, with collagen and mineral)
-Pulp cavity with vessels and nerves
What is the Root Canal
The part of the pulp in the root
Define Cementum
Bone layer of tooth root
-Attaches tooth to periodontal ligament
What is Periodontal Ligament?
- Anchors tooth in boney socket of the jaw
- Continuous with gingiva (gums)
Plaque
Film of sugar, bacteria and debris
Structure of the Tooth
(PIC)
Crown is covered by enamel and root is covered by cementum which meet at the neck. The Peridontal Ligament binds the cementum to spongy bone. Odontoblasts give rise to dentin which surrounds the pulp cavity contianing blood vessels and nerves which exit via the root canal
What is Enamel
The hardest component of the human body and the richest in calcium (95% calcium salts called Hydroxyapatite)
What does Ameloblast produce?
Enamel
Enamel Rods
Hydroxyapatite crystals form long, tightly packed enamel rods that extend the full thickness of the enamel
Can the Enamel part of the tooth repair itself?
No, Ameloblasts degenerate during tooth eruption
What is Hydroxypatite
95% calcium salts
Dentin
A hard but resilient calcified tissue (70% dry weight)
What is Outer Surface covered by?
Enamel (crown) and Cementum (root)
What is Organic Matrix (predentin) produced by?
Ondontoblasts
Organic Matrix (predentin) contains…
Type I Collagen and is mineralized by hydroxypatite crystals (mature dentin)
What are Ondontoblasts
Long lived cells which lie exclusively on the internal surface of the dentin
Ondontoblasts have…
Ondontoblast process which extend into small canals (dentinal tubules)
Dental Pulp
Gelatinous connective tissue which fills pulp cavity including the root canal
Is Dental Pulp highly vascularized and innervated?
Yes
Are Afferent Nerve Fibers in Dental Pulp pain SENSITIVE?
Yes ALL of them are- some extend into dentinal tubules
Access to root canal from Dental Pulp is via…
Apical Foramen
What happens as more dentin is laid down?
The pulp cavity diminishes in size
Cementum
Bone-like Calcified matrix that covers the Dentin of the root- is produced by cementocytes
- Provide anchor sites for collagen bundles (Sharpey’s Fibers) from Periodontal ligaments labile tissue sensitive to stress pressures
- Attaches tooth to PERIODONTAL LIGAMENT
Periodontal Ligament
Dense connective tissue which sends fibers into cementum which secures tooth to bony socket
-Acts as a “shock absorber” and allows limited movement of tooth in socket
What is Aveolar processes?
Aveolar bone of maxillary/mandible bones which form sockets for dental roots
Gingiva (gums)
Oral epithelium firmly bound to the periosteum of the alveolar process
Gingival Sulcus
Space between the free gingival and crown. The gingival sulcus is lined by non-keratinized epithelium
Key steps in teeth development
- Tooth formation begins at 6-7 weeks of gestation
- Crown formation begins before root formation
- Root formation occurs after the crown is mostly completed and is accompanied by tooth eruption
Different Stages in Tooth development
Bud, Cap ( early and later), and Bell
Enamel Organ During Development of Teeth
(ectoderm)- Cellular down-growth of oral epithelium which forms enamel-related structures
Dental Papilla During Development of Teeth
(mesoderm) forms dentin related structures and pulp
Mesenchyme During Development of Teeth
(dental sac) forms cementoblasts and periodontal ligament
Hard Palate
- Bony Anterior (2/3) pf palate which seperates nasal cavity from oral cavity
- Oral Mucosa (keratinized) is tightly bound to periosteum of bone
- Numerous minor salivary glands (mucus Secerting)
Soft Palate
- Soft Posterior (1/3) of palate which seperates nasopharnx from oropharnyx
- Uvula-small conical termination
- Large number of taste buds
What is the Tongue
A mass of interlacing skeletal muscle covered by a mucous membrane with specialized areas- articulation, mastication, taste, swallowing (deglutition), suckling.
What kind of tissue is found on the dorsal surface of the tongue?
Thick keratinized epithelium with special projections- the ventral surface is smooth, thin, and permeable
Oral portion (anterior 2/3) has…
lingual papilae on dorsal surface; ventral surface is smooth
Pharyngeal portion (posterior (1/3) has…
Surface lingual tonsils (cobblestone appearance)
Sulcus terminalis
V-shaped shallow groove seperating palatine and pharyngeal portions
Ventral Surface
Smooth, Permeable
Lingual Papilae
The dorsal surface of the anterior 2/3 of the tongue has special elevations or projections called Papillae
Filiform
most numerous, conical shaped, keratinzed, DO NOT HAVE TSTE BUDS
Fungiform
Mushroom shaped, interspersed among the filiform papillae (especially near the top of the tongue); CONTAIN A FEW TASTE BUDS on upper surface
Circumvallate
large circular structures (10-12) each with a surrounding “moat” located just in front of the sulcus terminalis
Glands of Von Ebner
Below papillae, deliver serous secretions onto moat (cleansing function)
Taste Buds (largest concentration) in…
intraepithelial structures within the moat’s case/wall
Papillae
Cover the anterior portion of the tongue
Filiform Papillae
most numerous but lack taste buds
Fungiform Papillae
Less numerous and contain scattered taste buds
Ciricumvallate Papillae
Least Numerous, largest and form V-shaped line just in front of the sulcus terminalis; Contain over half the taste buds
Taste Buds occur within…
Occur within the stratified squamous eputhelium of the tongue
Taste Bud Cells
half the cells are elongated GUSTATORY cells lined by microvilli- projecting through an opening called the TASTE PORE. The remaining supportive cells and basal stem cells are present
4 basic flavor
Sweet, Sour, Salt, Bitter
Intraepithelial Ellipsoid Structures composed of…
50 spindle shaped cells - Sensory cells have a high turnover (life span=10 days)
Apical portions of sensory cells from a…
Taste Pore (communicates with the oral cavity)
Taste pores have tight junctions with…
microvilli which project into the pore and are exposed to the micro environment (serve as taste receptors)
Sensory Cells have…
synaptic vesicles and synapse with gustatory nerve fibers
Number of taste buds increase/decrease with age
DECREASE
Lingual Tonsils are sub-epithelial aggregates of lymphoid nodules in…
Pharyngeal portion of the tongue
Lingual Tonsils- deep epithelial pits form…
crypts (1 per tonsil)
Lingual Tonsils- minor salivary glands secrete…
into crypts (unlike other tonsils)
Composition of Saliva
- Water 95%
- Proteins- Enzymes, mucus, IgA, lysosome, lactoferrin
- Electrolytes- K+, Ca2+, HCO3
Functions of Saliva
TABLE
Types of Salivary Gland
Major Salivary Gland and Minor Salivary Gland
Major Salivary Gland
(parotid, submandibular, sublingual)- grossly indentifiable, encapsulated, secrete on demand
Minor Salivary Gland
Submucosa of Oral Epithelium; small, not encapsulated, short ducts, continuous secretion, in various locations
Major Salivary Glands Cell Types
Serous Cells
Mucous Cells
Myoepithelial Cells
Plasma Cell
Major Salivary Glands Cell Types- Serous Cells
Abundant zymogen granules; secretion rich in water, electrolytes, amylase (oral starch digestion), IgA, and lactoferrin
Major Salivary Glands Cell Types- Mucous Cells
Secretion contains mucin (lubrication)
Major Salivary Glands Cell Types- Myoepithelial Cells
Facilitate movement of saliva
Major Salivary Glands Cell Types- Plasma Cells
secrete IgA
Secretion is a 2 stage process…
a. Primary Secretion by acini (facillicated by myoepithlial cells)
b. striated ducts special intratubular ducts lines by columnar cells with basal foldings and mitochondria; modify the primary secretion through an active electrolyte transport process
Secretion Control
Salivary secretion is mainly under autonomic nervous control- both sympathetic and parasympathetic
Secretory Control- ParaSympathetic Stimulation
Copious watery secretions
Secretory Control- Sympathetic Stimulation
Thick viscoid secretion (dry mouth)
Parotid Glands
- Produce 25% of saliva
- Largest Salivary glands
- Serous type (compound aveolar)
- Secrete water, electrolytes, amylase
- contain many IgA secreting plasma cells
- Parotid duct opens on inner surface of cheek across from upper second molars (Stensons Duct)
What are Stensons Duct
Where Parotid duct opens on inner surface of cheek across from upper second molars
Submandibular Glands
- Produce 70% of Saliva
- Lie along body of mandible
- MIXED TYPE: Serous predominates with Serous Demilunes (compound tubuloalveolar)-fairly rich in MUCIN
What are Wharton’s Duct
Submandibular ducts open on the floor of the mouth
Sublingual Glands
- Produce 5% of saliva
- Smallest; located in the floor of mouth
- MIXED TYPE: Mucous predominates with serous demilunes (compound tubuloalveolar) secretion also rich in mucin
What is Bartholin’s Duct?
Have multiple ducts that open posteriorly to the submandibular ducts
Comparison of salivary glands
PIC TABLE
Oropharynx
- conducts food from oral cavity to esophagus
2. Stratified squamous epithelium (non-keratinzed)
Nasopharynx
- Conducts air from the nasal cavities to the larynx and trachea
- Pseudostratified ciliated columnar epithelium (respiratory)
Characteristics of the outside of the lip
Characterized by fully keratinized stratified squamous epithelium with hair follicles and sebaceous glands embedded in the dermis.
Characteristics of the inside of the lip
Lined by a non-keratinized stratified epithelium supported by a lamina propria
Characteristics of the Tongue
Primarily a muscular organ covered by mucous membrane with stratified squamous epithelium.
-Parts of the tongue are modified to conform to its function as an organ of mastication of taste.
Which sections of the mouth are highly permeable to certain substances?
- The floor of the mouth (sublingual area)
- Ventral surfaces of tongue
