Histology of the Nasal and Oral Cavities Flashcards
What kind of epithelium makes up respiratory? What are its hallmarks?
Pseudostratified columnar ciliated
Cilia
Goblet Cells (TONS)
Thick basement membrane
What are the three regions of the nasal cavity? What divides these?
Nasal vestibule: just inside the nostrils, lined by skin
Respiratory region: inferior 2/3 of nasal cavities, lined with respiratory mucosa
Olfactory region: Apex (upper 1/3), lined by specialized olfactory mucosa
Nasal septum
What is the function of the nasal cavities? What enhances this function?
Adjust temperature (aka warm inhaled air) and humidity of inspired air
Large surface area provided by the turbinate bones
What are paranasal sinuses? What are they lined with?
Air filled spaces in the bones of the walls of the nasal cavity
Respiratory epithelium
How do sinuses communicate with the nasal cavities?
Narrow openings onto the respiratory mucosa
What kind of epithelium makes ups the nasal vestibule?
Keratinized squamous
What kind of epithelium makes up the respiratory region (posterior to vestibule)?
Pseudostratified columnar ciliated epithelium
What are the hallmarks of olfactory mucosa?
Thicker than respiratory
Lack goblet cells (don’t need because of olfactory glands
Thin basement membrane
What kind of epithelium makes up the olfactory mucosa? What is contained in the mucosa?
Pseudostratified ciliated columnar
Receptors for sense of smell
- olfactory glands –> serous secretions that dissolve odorant molecules
What are the main features of olfactory receptor cells?
Single dendritic process
Specialized non-motile cilia with odorant receptors
GPCRs: ligand binding causes signal to be sent to olfactory bulbs
Besides olfactory receptor cells, what other cell types are found in the olfactory mucosa? What are their functions?
Basal cells: stem cell for olfactory receptor cells and supporting cells
Brush cell: ciliated columnar epithelial cells in contact with CN V
Supporting/sustentacular cells: provide mechanical and metabolic support to olfactory receptor cells
Why do we need olfactory mucus lining?
To trap odorant molecules
Are individual neurons in the olfactory mucus specific or general for odorants?
Specific
Generally what lines the oral cavity? What is this divided into?
Oral mucosa
Lining
Masticatory
Specialized
What cell types make up the lamina propria of the oral cavity? How is this divided?
Fibroblasts, WBCs, collagen fibers
Papillary layer: superficial, loose CT, neurovasculature
Dense: deep, dense irregular CT, supportive
What are rete ridges?
Zig zags that keep oral mucosa attached (comparable to dermal papillae)
Where is masticatory mucosa found? What kind of epithelium is it composed of?
Hard palate, gingiva, dorsal surface of tongue AKA places where there is constant abrasion we need extra force and protection
- lots of rete ridges and highly interdigitated
Keratinized and/or parakeratinized stratified squamous epithelium
Where is lining mucosa found? What are its defining characteristics?
lips, cheeks, alveolar mucosal surface, floor of the mouth, inferior surfaces of the tongue and soft palate
Non keratinized stratified squamous epithelium
- fewer rete ridges and connective papillae
- distinct submucosa
What are the layers of lining mucosa?
Stratum basale: single later of cells on basal lamina
Stratum spinosum: several cells thick
Stratum superficiale: most superficial layer (surface layer of mucosa)
What kind of mucosa does the tongue have?
Masticatory and specialized mucosa (keratinized stratified squamous
- contains lingual papillae and taste buds
What are lingual papilla? What are the 4 kinds?
Keratinized epithelium with lamina propria
Small elevated structures of specialized mucosa (some associated with taste buds)
Filiform
Foliate
Fungiform
Circumvallate
What are the general features of filiform papillae? Function?
NO TASTE BUDS
(pine cone/pointy)
Move food toward pharynx for swallowing
What are the general features of foliate papillae? Function?
Vertical ridges on lateral surface of tongue in posterior region
(more rectangular/ square looking)
Trap partially digested food so can provide taste sensation
What are the general features of fungiform papillae? Function?
Provide taste on dorsal surface of tongue, not as many
What are the general features of circumvallate papillae? Function?
Mushroom shaped structure anterior to slcul terminalis, sunken appearance surrounded by trench
Hundreds of taste buds, big crevices
What are taste buds? What are they made of?
Barrel shaped organs that perceive food molecules
Comprise of 30-80 spindle-shaped cells that extend from the basement membrane
Microvili extend into taste pore
Where are neuroepithelial cells found? What do they synapse with?
From the basal lamina of the epithelium to the taste pore, extend microvili through the pore
Synapse w/ afferent sensory neurons of CN VII, IX, X
What are the supporting and basal cells of the taste bud?
Supporting: elongated cells that extend from basal lamina to the taste pore
- microvilli on apical surface, do not synapse with nerve
Basal: small cells located in the basal portion of the taste bud near the basal lamina, stem cells for supporting and neuroepithelial cells
What are the general characteristics of palatine tonsils?
Nonkeratinized stratified squamous epithelium
- densely populated with lymphocytes
Tonsillar crypts (10-20 deep invaginations)
Dense tissue acts as partial capsule
What are the general characteristics of pharyngeal tonsils?
Single structure found on posterior wall of nasopharynx
Covered with pseudostratified columnar ciliated epithelium
Thin underlying capsule, shallow infoldings but no crypts
What are the general characteristics of lingual tonsil?
Positioned along base of tongue
Covered with stratified squamous epithelium
Posses germinal centers (immune response)
LACKS A CAPSULE, varying number of crypts
What are the parts of a tooth?
Crown projects into oral cavity and protected by enamel
Root embedded in alveolar ridge of alveolus
Both root and crown made of dentin
Dentin encloses pulp chamber
Root invested in cementum
What is dentin made of?
calcified organiz matrix, calcium hydroxyapatite
Dentinal tubules= parallel tubes that radiate into the periphery of the dentin
What is enamel made of?
Parallel enamel rods of calcium hydroxyapatite
- cemented together by interprismatic material
HARDEST STRUCTURE IN BODY
Where do you find cementum?
Starts where enamel no longer is present, sits in tooth socket, anything below the gums
Anchors PDL
Covers the dentin in the root
Thicker towards apex of root
What composes the pulp of a tooth?
Loose mesnchymal CT
Collagen fibers, fibroblasts, mesenchymal stem cells
Highly vascular, well innervated, provides nutrition to dentin
What makes up the periodontium of a tooth?
Cementum
Periodontal ligament
Alveolar bone
Gingiva
Where does the periodontal ligament (PDL) insert? What is it made of?
Into the cementum and alveolar bone that lines the alveolus
Collagen fibers, dense CT
What do osteoclasts chew out when you loose a tooth?
Periodontal ligament
What is the pathway of tears?
Lacrimal gland= lateral, makes the tears and secrete them out onto eyeball then you blink and push tears medially toward lacrimal canaliculi with puncta which wick the tears into the lacrimal sac which goes down and drains into nasolacrimal duct which drains into the inferior nasal meatus
Why does your nose run when you try to suppress tears?
Obicularis oculi muscle attaches on lateral side of sac, you blink and pulls the lacrimal sac creating negative pressure and pulls tears down
What innervation causes tear production?
Greater petrosal n. (from CN VII) and deep petrosal n. form nerve to the pterygoid canal
Parasympathetic fibers synapse in the pterygopalatine ganglion and jump onto V2 zygomatic branch and then jump onto lacrimal n. of V1 via the communicating branch
Can you make tears if you lesion the trigeminal n. proximal to the ganglion?
Yes because axons are originating from the facial n. and just use the trigeminal as a scaffold
What are the chambers of the eye?
Anterior chamber= between cornea and iris/pupil
Posterior= between the iris/pupil and the lens and ciliary body
What is the ciliary body and ciliary processes?
Body= circumferential tissue inside the eye composed of the ciliary muscle and ciliary processes
Processes= secrete aqueous humor which fills the ant. and post. chambers
What is the flow of aqueous humor?
Ciliary process –> posterior chamber –> lens –> anterior chamber –> sclera venous sinus
How can you get glaucoma?
Blockage of Schlemm’s Canal aka sclera venous sinus compressing the optic n.
What is hyphema?
Rupture of blood vessel causing it to pool in the anterior chamber
Happens if you get hit in the eye
What happens when your eyes accommodate during the H test when the finger is brought close to your face?
Convergence of eyes
Pupil constriction via sphincter pupillae
Rounding of lens
