Histology of Taste and Olfaction

Question 1

What type of cells make up the respiratory epithelium?

Answer 1

pseudostratified columnar ciliated

goblet cells present

lamina propria has rich vascular network

Question 2

What are the 3 regions of the nasal cavities?

Answer 2

nasal vestibule: just inside nose, lined by skin

respiratory region: inf 2/3

olfactory region: upper 1/3; lined by special olfactory mucosa

Question 3

What are paranasal sinuses?

Answer 3

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

Question 4

How does the epithelium change from the nasal vestibule to the respiratory region?

Answer 4

vestibule = keratinized stratified squamous

respiratory = pseudostratified ciliated columnar

Question 5

What are the defining features of olfactory mucosa?

Answer 5

dramatically thicker

NO goblet cells

still pseudostratified ciliated columnar

olfactory glands and receptor cells present

Question 6

What do olfactory glands do?

Answer 6

serous secretions that dissolve odorant molecules

Question 7

What are the main cell types in olfactory mucosa?

Answer 7

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

Question 8

What are the fila of the olfactory n?

Answer 8

axons that extend through the ethmoid bone

together they make up the olfactory n

Question 9

What supports the mucosa in the oral cavity?

Answer 9

lamina propria

papillary layer: superficial, loose CT w/ neurovasculature

dense layer: deep, dense irregular CT

Question 10

Is there a submucosal layer in the oral cavity?

Answer 10

present in areas that need more support:

in cheeks, but not in hard palate

Question 11

Where is masticatory mucosa and what characterizes it?

Answer 11

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

Question 12

What is the difference btw parakeratinized and keratinized stratified squamous epithelium?

Answer 12

parakeratinized: retain nuclei
keratinized: no nuclei at outer surface

Question 13

Where is lining mucosa and what characterizes it?

Answer 13

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

Question 14

What are the 3 layers of lining mucosa?

Answer 14

from superficial to deep:

stratum superficiale

stratum spinosum: several cells thick

stratum basale: single layer resting on BL

Question 15

What type of tissue will you see beneath lining mucosa and submucosa?

Answer 15

skeletal muscle (of the cheeks)

Question 16

Where is specialized mucosa and what is it generally like?

Answer 16

associated w/ sense of taste

restricted to dorsal surface of tongue

keratinized epithelium and lamina propria

Question 17

What type of epi covers the tongue?

Answer 17

masticatory and specialized mucosa

Question 18

What characterizes filiform papillae?

Answer 18

look pointier compared to others

move food and give tongue velvety texture

NO taste buds

Question 19

What characterizes foliate papillae?

Answer 19

more rectangular looking

vertical ridges on lateral surface of tongue in more post regions

provide taste sensation

Question 20

What characterize fungiform papillae?

Answer 20

more rounded looking, but smaller than circumvallate

found in lesser numbers on dorsal surface of tongue

taste buds here

Question 21

What characterize circumvallate papillae?

Answer 21

7-15 raised mushroom-shaped structures anterior to sulcus terminalis

hundreds of taste buds present

Question 22

What characterize taste buds?

Answer 22

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

Question 23

What are the types of cells in a taste bud?

Answer 23

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

Question 24

How many tastes can a single bud discern?

Answer 24

can discern all 5, but appear to concentrate on 2 of 5

on palate: bitter and sour mainly

posterior pharynx and epiglottis: all 5

Question 25

What are the layers of exposed tooth from superficial to deep?

Answer 25

enamel –> dentin –> pulp

Question 26

Where is the neurovasculature of a tooth?

Answer 26

in the pulp

Question 27

Where is cementum?

Answer 27

surrounds dentin in the rooth –> PDL connects this to alveolar bone

Question 28

What makes up dentin?

Answer 28

calcium hydroxyapatite crystals

dentinal tubules = parallel tubes that radiate to the periphery of the dentin

Question 29

What makes up enamel?

Answer 29

parallel enamel rods of calcium hydroxyapatite

rods cemented together by interprismatic material

Question 30

What are lines of retzius?

Answer 30

lines of enamel laid down over time

Question 31

What makes up cementum?

Answer 31

calcium hydroxyapatite

covers dentin in the root

thicker toward apex of root

Question 32

What makes up pulp?

Answer 32

loose, mesenchymal CT

collagen fibers, fibroblasts, stem cells

highly vascular and innervated

nutrition to dentin, can form reactive dentin due to chronic injury

Question 33

Where should the gumline stop?

Answer 33

cementoenamel jxn

Question 34

What is the periodontium?

Answer 34

cementum, periodontal ligament, alveolar bone,a nd gingiva

PDL = collagen fibers anchoring cementum to alveolar bone

gomphosis joint

Question 35

What do odontoblasts do?

Answer 35

secrete predentin –> mineralizes to dentin

cells extend an odontoblast process, which is surrounded by new matrix and becomes entrapped in dentinal tubules

Question 36

What do ameloblasts do?

Answer 36

tall polarized cells in contact w/ dentin

secrete enamal matrix –> enamel

matrix is secreted from Tome’s process

lost during tooth eruption

Question 37

What do cementoblasts do?

Answer 37

secrete cementoid –> cementum

cells become entrapped forming cementocytes