Flashcards in 33 - GI System I Deck (95):
What are the three types of mucosa found in the oral cavity?
1 - Masticatory mucosa
2 - Lining mucosa
3 - Specialized mucosa
Where is masticatory mucosa found?
In places where abrasive forces are the greatest (chewing)
What areas does this include? (masticatory mucosa)
- Gingiva (gums)
- Palatine raphe (center line)
- Roof of mouth between gums and raphe
What does the epithelium in the masticatory mucosa contain?
An underlying lamina propria that is anchored to a basal lamina
What is found covering the hard palate?
Describe the mucosa of the hard palate
- Epithelium is made up of stratified squamous keratinized cells
- You will also find parakeritinized (partially)
- The keratinized superficial layers will be nonviable/dead
Describe the submucosa of the hard palate
Contains two layers of connective tissue
- Anterior layer: adipose
- Posterior layer: minor salivary glands present
What is Burton's line?
A blue/grey line on the margin of the gingiva that is indicative of LEAD POISONING - this is due to an actual deposition of lead
What is lining mucosa?
The second type of mucosa we listed that lines most of the oral cavity (like your cheeks)
What type of epithelium will you find in lining mucosa of the oral cavity?
Nonkeratinized stratified squamous (may find small islands of parakeratinized)
What are the three strata you will find in lining mucosa of the oral cavity?
1. Stratum basale
2. Stratum spinosum
3. Straum superficiale
What is the function of the submucosa below the lining mucosa?
Connective tissue that anchors the mucosa
What are filiform papillae?
- Specialized mucosa associated with the tongue
- Covers most of the tongue surface
- Accounts for the roughness of the tongue surface
- Consists of conical projections of keratinized epithelium
Do filiform papillae contain taste buds?
NO! This is the only type of papillae that don't contain any taste buds
What are fungiform papillae?
- Mushroom shaped projections that contain taste buds at their tip
- Consists of stratified squamous epithelium with partial keratinization
- Extensions of the lamina propria
What are circumvallate papillae?
- Largest of the four types of papillae
- Found proximal to the sulcus terminalis (V-shaped area at the back of the tongue)
- Contain taste buds
- Covered by stratified squamous epithelium
What types of secretions come from circumvallate papillae?
Serous gland secretions
What are foliate papillae?
Leaf shaped papilla that are found on the lateral margins of the tongue and are not well developed in humans
- Stratified squamous epithelium
- Contain taste buds
- Glands empty into the moats surrounding papillae
What are the three types of cells that constitute taste buds?
1 - Sensory cells
2 - Supporting cells
3 - Basal cells
Describe a sensory cell of a taste bud
- Contain microvilli on apical domain
- Taste receptors are within plasma membrane of microvilli which bind to "tastants"
What cranial nerves are involved with taste perception?
CN VII, CN IX, CN X (7,9,10, but no 8, even though eight is the "eater")
How is taste sensory information perceived?
Taste receptors within the plasma membrane of microvilli bind to tastants that pass through the taste pores where they make synaptic contact with cranial nerves VII, IX, or X depending on the location
Describe the supporting cells of the taste buds
- Support the sensory cells by insulating and separating each individual sensory cell
- This helps to avoid "cross talk"
- Supporting cells have microvilli on the apical domain
Describe the basal cells of the taste buds
- Stem cells
- Replenish the sensory and supporting cell populations when they die (every 10 days, so very active)
What are the three regions of the lip?
1 - Skin
2 - Vermillion zone (red free margin)
3 - Mucosa
Describe the skin region of the lip
- Stratified squamous, keratinized epithelium
- Hair follicles and sweat/sebaceous glands
- Dermis lies deep to epithelium
Describe the Vermillion zone of the lip
AKA red free margin
- Thin skin that allows the redness of the blood to be visible
- Lacks hair follicles
- Lacks sweat glands
Describe the mucosa of the lip
- Wet stratified squamous, nonkeritinized epithelium
- Contains lamina propria
Does the mucosa of the lip contain a submucosal layer?
Describe the submucosal layer of the lip
Lies deep to the mucosa and contains labial salivary glands - secretions empty into oral cavity
Skeletal muscle located between dermis and submucosa
What can result from exposure of the lower lip to extensive UV light?
Squamous cell cancer of the lip
- Bottom lip more vulnerable
What are the three main salivary glands?
1 - Parotid gland
2 - Submandibular gland
3 - Sublingual gland
What is unique about the parotid gland?
ONLY serous cells
- More darkly stained cells
- Acidophilic cytoplasm
What is unique about the sumandibular gland?
Contains both serous and mucous cells, but SEROUS cells predominate
What is unique about the sublingual gland?
Contains both serous and mucous cells, but MUCOUS cells predominate
Saliva is secreted by both acinar and ductal cells. What 6 components does the saliva contain?
1 - Protein
2 - Enzymes
3 - Ions
4 - Mucins
5 - IgA
6 - Lactoferrin
What is the function of protein in the saliva?
Forms a protective coat on the teeth - the "acquired pellicle"
What enzymes are found in saliva? What is their function?
The enzymes have digestive and antibacterial functions
- Amylase (carbohydrate)
- Lipase (lipids)
- Lysozyme (antibacterial)
- Lactoperoxidase (antibacterial)
What types of ions are found in the saliva?
Sodium, phosphate, calcium, potassium, chloride
What is the function of lactoferrin in the saliva?
Binds iron and therefore binds bacteria that thrive on iron - this means it is antibacterial in nature
What is the general tooth structure?
Describe the enamel
Describe the dentin
Lies deep to the enamel and deep to the cementum - appears yellow in life
Describe the cementum
Outer coating of the root
Does every tooth have a crown and a root?
What is the difference between the clinical crown and the anatomical crown?
Clinical crown is just the portion of the tooth that is exposed above the gum line - the anatomical crown is the entire portion that is covered by enamel and not cementum
What is inside the center of the tooth?
- Nerve fibers
- Connective tissue
What defines mature enamel?
96-98% is calcium hydroxyapatite (MINERALIZED)
There is very little organic component in enamel
What is the protein component of enamel (although there is very little of it)
Enamelins and tuftelins
What is the toughest substance in the body?
What is a carious lesion?
A cavity - an "injury" to enamel
Although enamel is very hard, it can see be damaged
What is the effect of bulimia on the enamel?
- Posterior aspect of the teeth
- Frequent acidic exposure
- It will appear yellow - the enamel is gone and you are looking at the dentin
- If the dentin is exposed, the nerve endings are exposed (painful)
What are the six stages of tooth development?
1 - Bud stage
2 - Cap stage
3 - Bell stage
4 - Appositional dentin and enamel stage
5 - Tooth eruption
6 - Functional tooth stage
Describe the bud stage of tooth development
- Prominent invagination
- Epithelium at base of invagination becomes enamel
What molecular signals initiate the bud stage?
FGF-4 and BMP-2, 4 and 7
What cells do teeth arise from?
Neural crest cells
Describe the cap stage of tooth development
- The oral epithelium undergoes differentiation
- Growth of the mesenchyme pushes the epithelium up
What molecular signals initiate the cap stage?
Activin beta-A and BMP-4
What does the inner enamel organ become?
Ameoblasts that synthesize enamel
What lies below the mesenchyme?
Describe the bell stage
- Named after the bell shaped structure that form
- During this stage, four clearly defined tissue components form
What are the four tissue components that form during the bell stage?
1 - Outer enamel epithelium
2 - Stellate reticulum
3 - Stratum intermedium
4 - Inner enamel epithelium
What are the two components of the inner enamel epithelium?
- Ameloblasts (synthesize enamel)
- Central core of blood vessels and nerve fibers (dental papillae)
What are ameloblasts derived from?
Ectoderm ("sextoderm" - pretty teeth)
What do odontoblasts secrete?
What cells do odontoblasts arise from?
- Neural crest cells
- Ectoderm as well
- Central core components
Describe the stage of tooth eruption
- Growth from the previous stages continues
- Ameloblasts are completely gone (no further enamel production)
Describe the stage of the functional tooth
Begins when tooth eruption is done
Describe the secretory stage of ameloblasts
- Secretory ameloblasts will rest on the basal lamina
- External to the basal lamina there are cells of the stratum intermedium
What is the function of the stratum intermedium during ameloblast secretion?
The stratum intermedium transports cells to ameloblasts in order to help build and release enamel
Describe the maturation stage of ameloblasts
- The initial secretion of enamel is NOT mature
- Initially, the stratum intermedium is absent
- A papillary layer is present instead
What is a ruffled border? What is the function?
The "ruffled border" describes the initial appearance of enamel when it is in the stage of organic material uptake (before mineralization)
The ruffled border is encessary for an increased surface area, better uptake
What is a smooth border? When does this occur
When the smooth border develops, there is a decrease in the uptake of organic components and mineralization begins
Compare and contrast cementum and bone
- Very similar
- Both are about 65% mineralized (not as mineralized as enamel)
- Bone is vascularized, cementum is NOT vascularized
What are cementoblasts?
- Derived from mesenchyme
- Actively secrete cementum
- Located between the surface of cementum and the periodontal ligament
When do cementoblasts become cementocytes?
When they are completely surrounded by cementum that they have secreted (kind of like bone)
What type of structures do cementocytes exist in?
Cementocytes and their processes are found in lacunae and canaliculi (kind of like bone)
What part of the cementum is acellular?
Upper root area
What part of the cementum is cellular?
Lower root area (thicker part)
- Running from the cementum to the bone, there are coarse, acidophilic type I collagen fibers
What is the role of Sharpey's fibers?
Periodontal ligaments that help anchor the tooth within the socket
How mineralized is dentin?
The third most mineralized... component of the tooth - 70% mineralized
What is predentin?
The initial elaboration of dentin that needs further mineralization
What important proteins are found in dentin?
What are odontoblasts?
Cells for the synthesis and elaboration of dentin
What are odontoblasts derived from?
Neural crest cells and neural ectoderm
What are dentinal tubules?
Tubes that go through the entire thickness of the dentin and contain cellular processes that extend from odontocytes
What can be seen wrapped around dentinal tubules?
What happens when dentin becomes exposed without the protection of cementum or enamel?
The tooth becomes over sensitive to hot or cold because the fluid in the dentinal tubule will change temperature and the nerve fibers wrapping around them will detect it
What is the treatment for tooth sensitivity? How does it work?
Sensodyne - acts as a plug for the tubule, unfortunately only a short-term solution
How long are odontoblasts around for?
Unlike ameloblasts, these cells persist throughout life - they are elaborating dentin on the pulp cavity side of the dentin (innermost)
Where do nerve fibers enter the pulp cavity?
Through the vascular opening along with the vessels for blood supply
Where are odontoblasts found?
On the inner aspect of the pulp cavity
What happens to the pulp cavity as we age?
The dimensions decrease as we age because the dentin is being added from the outside, so the walls are closing in on you