Histology of Taste and Olfaction Flashcards
What type of cells make up the respiratory epithelium?
pseudostratified columnar ciliated
goblet cells present
lamina propria has rich vascular network
What are the 3 regions of the nasal cavities?
nasal vestibule: just inside nose, lined by skin
respiratory region: inf 2/3
olfactory region: upper 1/3; lined by special olfactory mucosa
What are paranasal sinuses?
air-filled spaces in the bones of the walls of the nasal cavity
extensions of the respiratory region of the nasal cavity, lined by respiratory epithelium
communicate w/ nasal cavities
this is where you get sinus infections
How does the epithelium change from the nasal vestibule to the respiratory region?
vestibule = keratinized stratified squamous
respiratory = pseudostratified ciliated columnar
What are the defining features of olfactory mucosa?
dramatically thicker
NO goblet cells
still pseudostratified ciliated columnar
olfactory glands and receptor cells present
What do olfactory glands do?
serous secretions that dissolve odorant molecules
What are the main cell types in olfactory mucosa?
olfactory receptor cells: single dendrite, nonmotile cilia
basal cells: stem cells for olfactory receptor and supporting cells; deeper in mucosa
supporting/sustentacular cells: mechanical and metabolic support
What are the fila of the olfactory n?
axons that extend through the ethmoid bone
together they make up the olfactory n
What supports the mucosa in the oral cavity?
lamina propria
papillary layer: superficial, loose CT w/ neurovasculature
dense layer: deep, dense irregular CT
Is there a submucosal layer in the oral cavity?
present in areas that need more support:
in cheeks, but not in hard palate
Where is masticatory mucosa and what characterizes it?
hard palate, gingiva, and dorsal surface of tongue
keratinized and/or parakeratinized stratified squamous epi
(paraK in areas w/ more abrasion)
a lot of rete ridges and papilla to help anchor mucosa
thin or absent submucosa
What is the difference btw parakeratinized and keratinized stratified squamous epithelium?
parakeratinized: retain nuclei
keratinized: no nuclei at outer surface
Where is lining mucosa and what characterizes it?
lips, cheeks, alveolar mucosal surface, floor of the mouth, inf surfaces of the tongue and soft palate
nonkeratinized strat squa, but may be parakeratinized in areas of abrasion
3 layers: stratum basale, spinosum, superficiale
fewer rete ridges and CT papillae
What are the 3 layers of lining mucosa?
from superficial to deep:
stratum superficiale
stratum spinosum: several cells thick
stratum basale: single layer resting on BL
What type of tissue will you see beneath lining mucosa and submucosa?
skeletal muscle (of the cheeks)
Where is specialized mucosa and what is it generally like?
associated w/ sense of taste
restricted to dorsal surface of tongue
keratinized epithelium and lamina propria
What type of epi covers the tongue?
masticatory and specialized mucosa
What characterizes filiform papillae?
look pointier compared to others
move food and give tongue velvety texture
NO taste buds
What characterizes foliate papillae?
more rectangular looking
vertical ridges on lateral surface of tongue in more post regions
provide taste sensation
What characterize fungiform papillae?
more rounded looking, but smaller than circumvallate
found in lesser numbers on dorsal surface of tongue
taste buds here
What characterize circumvallate papillae?
7-15 raised mushroom-shaped structures anterior to sulcus terminalis
hundreds of taste buds present
What characterize taste buds?
barrel-shaped organs that perceive food molecules
oval, pale-staining bodies that extend thru the thickness of the epithelium
30-80 spindle-shaped cells that extend from the BM
What are the types of cells in a taste bud?
neuroepithelial cells: elongated cells extend from BL to taste pore –> microvilli thru pore –> synapse w/ CN 7, 9, or 10
supporting cells: similar to neuroepithelial cells, just don’t synapse w/ nerve cells
basal cells: small, in basal part of bud near BL; stem cells for other types
How many tastes can a single bud discern?
can discern all 5, but appear to concentrate on 2 of 5
on palate: bitter and sour mainly
posterior pharynx and epiglottis: all 5
What are the layers of exposed tooth from superficial to deep?
enamel –> dentin –> pulp
Where is the neurovasculature of a tooth?
in the pulp
Where is cementum?
surrounds dentin in the rooth –> PDL connects this to alveolar bone
What makes up dentin?
calcium hydroxyapatite crystals
dentinal tubules = parallel tubes that radiate to the periphery of the dentin
What makes up enamel?
parallel enamel rods of calcium hydroxyapatite
rods cemented together by interprismatic material
What are lines of retzius?
lines of enamel laid down over time
What makes up cementum?
calcium hydroxyapatite
covers dentin in the root
thicker toward apex of root
What makes up pulp?
loose, mesenchymal CT
collagen fibers, fibroblasts, stem cells
highly vascular and innervated
nutrition to dentin, can form reactive dentin due to chronic injury
Where should the gumline stop?
cementoenamel jxn
What is the periodontium?
cementum, periodontal ligament, alveolar bone,a nd gingiva
PDL = collagen fibers anchoring cementum to alveolar bone
gomphosis joint
What do odontoblasts do?
secrete predentin –> mineralizes to dentin
cells extend an odontoblast process, which is surrounded by new matrix and becomes entrapped in dentinal tubules
What do ameloblasts do?
tall polarized cells in contact w/ dentin
secrete enamal matrix –> enamel
matrix is secreted from Tome’s process
lost during tooth eruption
What do cementoblasts do?
secrete cementoid –> cementum
cells become entrapped forming cementocytes
