Dr. Mhawi 1 Digestive System 1 Tongue, Salivary Glands, and Teeth Flashcards
What are the 3 types of oral mucosa in the oral cavity?
- Masticatory mucosa
- Lining mucosa
- Specialized mucosa
Masticatory mucosa if found on the ____ and ____
Has both _____ and ______ stratified squamous epithelium
gingiva and hard palate
keratinized and parakeratinized
In parakeratinized epithelium: superficial cells do not lose their nuclei
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True or False: Lining mucosa is non-kerantinized
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True
Where is specialized mucosa found?
dorsal surface of the tongue.
(specialized in sensation and taste)
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What are the 2 function s of oral mucosa?
•Barrier:
- junctions between epithelial cells isolate the environment of the mouth cavity from the surrounding tissues
•Protection:
- Oral cavity is protected from pathogens by combined actions of the epithelial cell junctions, migratory neutrophils, and saliva
Saliva contains antibodies
Explain this image?
epithelial cells of the hard palate. Both keratinized and parakeratinized epithelial cells are visible.
Explain this image
8.6.1
Both lips contain well-developed core of striated muscles (M)
- Highly mobile
- Help with ingestion and speech
Have three differently covered surfaces:
External surface
Covered by the skin
Contains hair follicles (F) and associated sebaceous glands (S), and sweat gland
Inner surface
Lined by lining mucosa (LM)
Many minor salivary glands (G) open
Vermilion zone (V)
Transitional zone between the lining mucosa and skin
Covered with very thin lightly keratinized stratified squamous epithelium
- Rich in sensory innervations and capillaries
- No hair follicles or salivary and sweat glands
Explain the 3 surfaces of the tongue.
Composed of
Striated muscles
- AKA lingual muscles
- Arranged in bundles organized in 3 planes
- Each plane arranged at right angle to the other
- Muscle arrangement permits great flexibility
Dorsal surface
- Covered with mostly keratinized epithelium
- Epithelium raised into small projections called lingual papillae
Ventral surface
- Covered with non-keratinized epithelium
- No papillae
Section of the Tongue
______ are specialized mucosal elevations that are found on the dorsal surface
Lingual papillae
What are th 4 types of lingula papillae?
- Filiform papillae
- Fungiform papillae
- Circumvallate papillae
- Foliate papillae
nAll contain taste buds except for filiform papillae
Explain the function and characteristics of filiform papillae.
8.6.1
- Smallest but most numerous
- Tapered projections
- Point toward rear of tongue
- Composed of keratinized stratified squamous epithelium and core of l_amina propria_
Low rate of desquamation results in white coating
•No taste buds present
Filiform papillae serve only mechanical role
Explain the function and characteristics of fungiform papillae.
- Scattered among filiform and project above them
- Covered with relatively translucent non-keratinized epithelium
Capillaries in underlying lamina propria show through it
•Papillae look red in gross appearance
•TASTE BUDS are present in epithelium on _dorsal surfac_e of fungiform papillae
Explain the image
Upper panel, a photograph of the posterio-dorsal surface of the tongue. Fungiform papillae appear red due to the covering with relatively translucent nonkeratinized epithelium, that makes the underlying capillary of the lamina propria to show through. Note the presence of bulges at the base of the tongue (appear as ridges) reflecting underlying lingual tonsils in the lamina propria.
Lower panel, a micrograph of one of the fungiform papilla. Fungiform papilla projects above the surrounding filiform papillae (small solid arrows). Note the presence of the taste buds (dashed arrows) in the epithelium of the fungiform papilla.
Explain the function of circumvallate papillae and the image.
8.6.1
- Large, dome-shaped
•Located just anterior to SULCUS TERMINALIS
Humans have 8-12
Each papilla is surrounded by a moat-like space lined with stratified squamous epithelium
Identify structures in the image.
no text.
- 6.1
- 6.1
Id slide and characteristics.
circumvallate
Explain image
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8.6.1
Location of papillae and sulcus termalis
What gland is this? Explain image
Foliate Papillae
- Located near the b_ase at lateral margins of tongue_
- In the form of parallel ridges of mucosa
- Papillae are separated by mucosal clefts
- Small serous Von Ebner’s glands empty into clefts
Lower panel: In histological cross section, foliate papillae are visible as parallel ridges separated by mucosal clefts. SG, serous glands of Von Ebner
8.6.1
How to differentiate lingual circumvallate and foliate papillae?
However, the appearance of taste buds in the apposed lateral walls of adjacent papillae helps in discriminating foliate papillae from circumvallate
NF, gustatory nerve fiber. Nuclei of the associated Schwann cells are visible.
Explain this image.
8.6.1
Upper panel: Micrograph of a taste bud. The lightly stained cell of the bud are extending through the thickness of the epithelium. The taste pore (arrow) is visible in some of these buds .
Lower panel: Drawing of a taste bud, showing the taste cells and the taste pore. In addition to the taste cells, the drawing also illustrates other cell types (basal and supporting) and the nerve endings of the gustatory afferent nerve fibers.
Explain this image and the characteristics of taste (sensory) cells.
- Chemoreceptors
- Elongated and most numerous
- L_ightly-stained nuclei_
- Apical surface has microvilli
- Apically cells connected to each other or to adjacent supporting cells by t_ight (occluding) junction_
- Basally synapse with processes (dendrites) of sensory neurons
(cranial nerves VII, IX, X)
•Turnover time 10 days
Photomicrograph of a taste bud.
This high-magnification photomicrograph shows the organization of the cells within the taste bud. The sensory and supporting cells extend through the full length of the taste bud. The apical surface of these cells contains microvilli. The basal cells are located at the bottom of the taste bud. Note that the taste bud opens at the surface by means of a taste pore.
Explain this image
Taste bud showing sensory, supporting and basal cells. Note that the nuclei of the sensory cells are lightly stained in comparison with the supporting and basal cells Red arrow indicates the taste pore.
What are the 4 parts of the teeth?
- Enamel: covers the crown
- Cementum: covers the root
- Dentin: surrounds the pulp
- Pulp: central loose connective tissue
What are the characteristics of enamel?
Hardest substance in body
98% hydroxyapatite (calcium phosphate)
Hydroxyapatite arranged in RODS or PRISMS
nEach rod spans the enamel layer
Each rod is produced by one ameloblast before tooth eruption
Enamel becomes acellular after tooth eruption
In section prepared by ground tooth technique, enamel appears striated
•Striations called LINES OF RETZIUS
Appear uneven
Represent a record of the path ameloblast has taken during the enamel deposition
Ground tooth (or bone) is a special technique by which the tooth/bone is cut thin enough (without demineralization with acids) by a sharp saw and examined with or without staining. This technique helps with the visualization of certain features in tooth (rods or prisms) and bone (layers of bone matrix in Haversian system and/or Canaliculi).
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What is amelogenesis and what are its stages?
Amelogenesis is the process of enamel formation
Enamel formed in two stages:
- Secretory stage
- Maturation stage
What is the secretory stage of amelogenesis?
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- Ameloblasts secrete organic matrix
- During matrix deposition ameloblasts move away from the dentinoenamel junction (previous slide and red arrow in lower panel of this slide)
- Movement takes uneven course
- Matrix deposition continues until enamel reaches full thickness
Upper panel: Light micrograph of the enamel formation. The enamel is deposited by the ameloblasts over pre-existing thin slab of dentin before tooth eruption. Ameloblasts move away from the dentinoenamel junction as the amelogenesis continues. The white stripe visible between the dentin and the enamel is an artifact resulted from the separation of the enamel from the dentin, most likely during the preparation of the section. Lower panel is a high magnification of the dentinoenamel junction within the boxed area in the upper panel. In this ground tooth technique, the enamel rods (prisms) appear uneven, a reflection of the uneven course the ameloblasts take during the deposition of the enamel.
What are the characteristics of cementum?
Covers root of tooth
- Root fits into socket of bone (alveolus)
Cementum has 50% minerals
secreted by CEMENTOCYTES
closely resemble osteocytes
Cementum is thin layer of bone-like material
Has lacunae filled with cementocytes, which connect with each other by canaliculi
Cementum is avascular
Nourishment is provided via blood vessels in the adjacent periodontal ligament
How is dentin deposited from the odontoblast?
Dentin is deposited from branched apical processes
- Called odontoblast processes
- Processes become longer as the odontoblast is displaced toward the pulp cavity during dentin deposition
Odontoblasts are responsible for the _mineralization o_f the dentin
Left) photomicrograph and (right) interpretive EM drawing of odontoblasts. Extending into the dentin from the cell apex, there is a light-staining branched odontoblast process that lacks cisternae of rER and Golgi. Secretory granules are present in this process and its branches.
Odontoblast processes contained in canals called ______
DENTINAL TUBULES
A: An illustration showing the dentinal tubules (blue) within which the odontoblast processes are extended. Unmyelinated nerve fibers (yellow) extend to a short distance inside the dentinal tubules, as well. B: High-resolution SEM of dentinal tubules. Many dentinal tubules run through the dentin (De) matrix. The 3- to 4-µm-diameter processes of odontoblasts (Od) are in the tubules.
What are the characteristics of pulp?
8.6.1
Pulp is loose connective tissue
Highly i_nnervated and vascularized_
Myelinated nerve fibers and vessels enter pulp from the apical foramen
Some afferent (sensory) nerve fibers lose myelin and extend short distances into dentinal tubules
Transduce stimuli from tooth surface
Light micrograph of cross-sectioned tooth. The section reveals the mature dentin and the lightly stained immature predentin secreted by the odontoblasts. The pulp cavity is filled with highly innervated and highly vascularized loose connective tissue.
Explain this image.
Sections show both dense and loose connective tissue
Loose connective tissue contains blood vessels nerves, and GAGs
Periodontal ligaments attaches the cementum (C) to the alveolar bone (B). D, dentin. Sharpey’s fibers are collagen fibers that are embedded in the cementum at one end (arrowheads) and in alveolar bone at the other (arrows).
What are the characteristics of dense connective tissue of the periodontal ligament.
8.6.1
Dense connective tissue consists of bundles of type I collagen fibers and fibroblasts
Periodontal ligament also has OXYTALAN FIBERS
•stain with elastic stains
TEM electron micrograph of the boxed area of the periodontal ligament in the previous slide. OF, Oxytalan fibrils (very immature elastic fibers); CF, type I collagen fibrils.
Explain this image
8.6.1
Longitudinal section of demineralized tooth. The enamel (E), which is highly calcified tissue, was completely removed leaving a space (represented by the area surrounded by the dashed line). The asterisk is placed in the gingival sulcus. A, alveolar bone; C, cementum; D, dentine; G, gingiva; PL, periodontal ligament
