12.1 GI System Flashcards
What is the Vermillion Border, and what are some characteristic structures found on specifically on either side of it?
= region of lip where integument meets oral cavity
- on integument side of lip: hair follicles, sebaceous glands, eccrine sweat glands (characteristic of integument)
- on oral cavity side: minor salivary glands (characteristic of oral cavity epithelia)
- In between the structures of the two sides is the orbicular is iris
What is the orbicularis iris?
= skeletal muscle that forms a sphincter around the mouth
- located in-between the oral cavity and the integument sides of the lip
Describe the characteristics of the tongue
- body of the tongue is composed of skeletal muscle fascicles in triorthogonal arrangement
- surface of the tongue = SSK + contains folds called papillae
- also see von Ebner’s Glands
- 3 types of papillae are found
1) Filiform papillae
2) Fungiform papillae
3) Circumvallate (Vallate) papillae
What are the filiform papillae?
- the most common form of papillae on the tongue surface
- papillae = folds in the tongue
What are the fungiform papillae?
- the second most common papillae found in the tongue epithelium
- are mushroom shaped
- host the tastebuds near the lumenal surface
- smaller than vallate papillae
What are the circumvallate (vallate) papillae?
- larger, but least prominent of the three types of papillae found in the tongue
- contain lateral taste buds apposed to a moat
- form a V nearer to the root of the tongue
What are Von Ebner’s Glands?
- found novelly emptying a pure serous product into the moat of the tongue
What are the 3 mineralized tissues that make up the adult tooth and which makes up the outside of the tooth?
1) - Enamel on the outside
2) - dentin on the inside (surrounds the pulp cavity)
3) Cementum - (doesn’t really become present until the adult tooth or after the root stage)
What is the Pulp cavity
- the interior of the tooth
- Surrounded by dentin (interior mineralized tissue of the tooth)
- comprised of innervated, vascularized CT
What are ameloblasts? Describe their function and presence in the adult structure.
- Produce enamel of the tooth
- enamel is produced before the tooth erupts
- they are lost before the tooth erupts and are not present in the adult tooth
What are Ordontoblasts? Describe their function and presence in the adult structure.
- Produces predentin (unmineralized dentin)
In the adult structure:
- these cells remain present on the inner surface facing the pulp cavity
- maintain processes inside the dentin in dentinal tubules
Define the anatomical crown and distinguish it from the clinical crown
- The anatomical crown is the enamel-covered surface of the tooth
- the visible portion of that enamel defines the clinical crown
- the difference between the two is the surface of the tooth apposed to the junctional epithelium across the gingival sulcus
What is the gingival sulcus?
- where the surface of the tooth is apposed to the junctional epithelium
What is the gingiva?
= specialized region of mucosa immediately surrounding the tooth
What are cementocytes/cementoblasts? Describe their function and presence in the adult structure.
- Cementoblasts - produce cementum
- cementum is the third mineralized substance of the tooth –> covers dentin of the tooth root (instead of enamel)
- -> Called cementocytes when they are trapped in lacunae of the cellular cementum
- Cementocytes are lost nearer to the dentin surface - form a complementary region of acellular cementum
What is the periodontal ligament?
- is the interface with the cementum and surrounding bone (mandible or maxilla)
- connect to either side via Sharpey’s Fibers - oriented perpendicularly to the collagen of the ligament (larger ones connect to the bone)
What are Sharpey’s Fibers?
- fibers that connect the PDL to the cementum and the surrounding bone (mandible or maxilla)
- larger ones connect into the bone structure
- are oriented perpendicularly to the collagen of the PDL
Describe the Dentinal Lamina Stage of tooth development
- oral epithelium has been indented
- mesenchyme condensation induced by ectomesenchymal cells is seen (formally neural crest cells)
Describe the cap and bell stage of tooth development (why they are named that)
- Named for the general shape of the enamel organ
- organization of the shape of this enamel organ controls the tooth shape
What is the enamel organ?
= sac-like structure consisting of an
1) inner enamel epithelium - containing ameloblasts
2) outer enamel epithelium - surrounding the stellate reticulum
What is the stellate reticulum
- surrounded by the outer (and inner) enamel epithelium
- network of star-shaped cells
- through organizing the shape of the enamel organ around it –> controls the tooth shape
What is Hertwig’s Epithelial Root Sheet (HERS)?
= a band of cells that induced dentin formation beneath the cervical loop (the base of the future anatomical crown)
- this elongates the tooth root during the root stage
What is the cervical loop?
= the base of the future anatomical crown
- the point between the outer enamel epithelium and inner enamel epithelium in the cap and bell stages
What are the two parts of the oral cavity?
1) Oral Vestibule
2) Oral Cavity Proper
What is the oral vestibule?
= the space between the cheeks and anterior surface of the tongue
What is the oral cavity proper?
= space between the upper and lower dental arches - from inter surface of teeth to oral pharynx
- extend superior to hard palate (bony palate) and to the soft palate (muscular palate)
Describe the tissue organization of the oral cavity
- minor salivary glands are found throughout the oral cavity
- it is lined by oral mucosa - formed by epithelium + underlying CT (no muscular is mucosae layer here)
- CT of the oral mucosa is anchored directly to bone or underlying submucosal layer
What are the 3 types of oral epithelium mucosa?
1) Masticatory Mucosa
2) Lining Mucosa
3) Specialized Epithelium
Describe the location of the Masticatory Mucosa of the oral cavity
= regions of oral cavity exposed to considerable friction
- will see ketatohyalin granule-containing cells
- located where chewing takes place:
1) Gingiva
2) Hard palate
3) Dorsal surface of the tongue
[1,2 have the most developed keratin layer]
What is the morphology of the Masticatory Mucosa of the oral cavity?
- SSK or SSParaK
- SSK = no nuclei in superficial cells, intensely eosinophilic staining
- SSPK = only described as normal in oral cavity, most superficial cells with stain lightly for keratin, but do not loose their nuclei (may have piqnotic nuclei)
Describe the function of the masticatory mucosa of the oral cavity.
= provide a tough inflexible layer that will resist abrasion (is tightly bound to lamina propria)
- will see ketatohyalin granule-containing cells
Describe the characteristics of the lining mucosa including the three layers of the epithelium from muscosa inwards.
- covers majority of the oral cavity
- morphology: SSNK of varying thickness (but overall thicker than masticator epithelium)
- not subject to high levels of friction
- is flexible - allows movement of underlying tissues and muscles
- Contains three layers:
1) Stratum Granulosum
2) Stratum Spinosum
3) Stratum Basale
Where do you find the lining mucosa of the oral cavity?
- not found in areas where chewing takes place
- not subject to high levels of friction - is flexible
- found in:
1) Cheeks,
2) Floor of mouth
3) inferior surface of tongue
4) Soft palate
5) inner/oral surface of lip
6) Under tongue (clinically important) - the SSNK epithelia is much thinner, is most permeable in oral cavity, has high vascularization (aka is site for entry of sublingual meds)
Describe the Specialized Epithelium and whats so special about it.
- contains the taste buds
- tastebuds = clusters of epithelial cells
- Taste buds contain 3 types of cells
1) Neuroepithelial Cells
2) Supporting Cells
3) Basal Cells
What is the taste pore?
- made up of 50-90 fusiform cells that have narrow apical ends
- these cells converge to form the taste pore
- opens into the oral cavity
Describe the 3 cell types found in the taste bud
1) Neuroepithelial Cell (sensory cell)
- has high rate of turnover (7-10 days)
- has microvilli - extend from apical cell through taste pore
- microvilli have receptors that interact with tastents in oral cavity
- forms synapse with afferent neuron - brings taste info to CNS
2) Supporting Cells
- has microvilli don’t synapse with nerve cells
3) Basal Cells
- Small cells
- FXN as stem cell for both #s 1 and 2
Describe the secretory element of salivary glands and the three cell types that could be present
- blind ended duct - composed of secretory cells
- contains 3 types of cells all in contact with lumen and secrete into it
1) Serous Cells - secrete only serous product = a watery, protein filled saliva (proteins are stored in apically located zymogen granules)
2) Mucous Acini - secrete mucous product stored in mucinogen granules
- H&E stain - cells appear empty, nucleus is pushed to basal aspect of cell
3) Mixed Acini - contain serous + mucous producing cells
- mucous cells appear to have cap of serous cells (serous demilunes)
Describe the myoepithelial cells of salivary glands
= specialized epithelial cells
- -> contractile cells with numerous processes containing actin filaments
- located between basal plasma membrane of secretory cell and basal lamina of epithelium
- also found in the proximal duct region
Describe the salivary ducts
= 3 separate ducts (nearest to secretory element) that transport + modify saliva
1) Intercalated ducts = low cuboidal cells
2) Striated ducts = columnar shaped cells
- contain basal infoldings that increase the number of mitochondria available for ion transport
3) Excretory duct = pseudostratified epithelium
- forms from smaller ducts coming together
- rungs in large amount of CT
- opens into oral cavity
Summarize the flow of saliva towards the lumen of the oral cavity.
1) Serous/Mucous/Mixed Cells
2) Small interlobular duct (intercalated duct)
3) Striated Duct
4) Interlobular duct
5) Stratified Columnar epithelium
6) Main Duct
What ar the two overarching divisions of salivary glands of the oral cavity
1) Major salivary glands
- 3 paired major salivary glands
- A. Parotid, B. Submandibular, C. Sublingual
2) Minor Salivary glands
- located throughout the oral cavity in CT layer
ex. palantine salivary glands
Describe the minor salivary glands
- located throughout the oral cavity in the CT layer
- can be named based on location (ex. palatine salivary glands)
- are all mixed glands (mucous + serous) except Von Ebner’s glands (is only serous)
Describe Von Ebner’s glands
- the only minor salivary glands that are all serous cells
- these glands are associated with vallate papilla of the tongue (which are lined with taste buds)
- the serous product of these glands FXNs to clear the area for new taste stimuli
Describe the parotid glands
- one of the major salivary glands
- purely serous glands
- contain large parotid excretory duct that releases saliva in the general area of the second molar tooth of the upper jaw
- gland undergoes involution with age
- is encapsulated in dense CT sheath - limits its mobility
Describe the Submandibular Glands
- located below the mandible
- excretory duct releases saliva below tongue (sublingually)
- is a mixed gland (primarily serous secretion though)
Describe the sublingual gland
- located below the tongue
- multiple duct profiles real sing into area under the tongue
- has very low profiles of duct, very small ducts with no singular large excretory duct
- some of the ducts open into oral cavity + some into duct of submandibular gland
- primarily mucous secreting gland
- thick viscus product of this gland helps food stick together to form the bolus
