Histology of the Nasal and Oral Cavities Flashcards
What makes of respiratory epithelium?
Pseudostratified columnar ciliated epithelium
What are the hallmarks of respiratory epithelium?
Cilia, a gazillion goblet cells, and thick basement membrane
What is the lamina propria?
Rich, vascular network with complex set of capillary loops
What is the nasal cavity divided by? What are the regions?
Divided by nasal septum; regions are nasal vestibule, respiratory region, and olfactory region
Where is the nasal vestibule located? What is it lined by?
Just inside the nostrils, lined by skin
What is the respiratory region and what is it lined by?
Inferior 2/3 of nasal cavities, lined with respiratory mucosa
What is the olfactory region and what is it lined by?
Located at the apex (upper 1/3), lined by specialized olfactory mucosa
What is the function of the nasal cavities?
Adjusts temperature and humidity of inspired air; enhanced by large surface area provided by the turbinate bones
What is the nasal vestibule made of?
Keratinized stratified squamous epithelium (skin)
What is the respiratory region made of?
Pseudostratified columnar ciliated epithelium
What are paranasal sinuses?
Air-filled spaces in the bones of the walls of the nasal cavity; sinuses communicate with the nasal cavities via narrow openings onto the respiratory mucosa; often subject to acute infection after viral infection of the upper respiratory tract and severe infections may require physical drainage
What are the hallmarks of olfactory mucosa?
Dramatically thicker, lacks goblet cells, and a thin basement membrane
Why don’t we have goblet cells in the olfactory mucosa?
Because we have olfactory glands
What is the olfactory mucosa made of?
Pseudostratified ciliated columnar epithelium
What do olfactory glands secrete?
Serous secretions that dissolve odorant molecules
What are olfactory receptor cells?
Have single dendritic process; specialized, non motile cilia w/ odorant receptors; ligand binding causes signals to be sent to olfactory bulb
What are basal cells?
Stem cells for olfactory receptor and supporting cells
What are brush cells?
Ciliated, columnar epithelial cells, in contact with CN V
What are supporting/sustentacular cells?
Mechanical and metabolic support to olfactory receptor cells
What is the oral mucosa?
Protective mucous membrane that lines the oral cavity
What is the oral cavity made of?
Stratified squamous with varying keratinization
What is the oral mucosa divided into?
Lining, masticatory, and specialized mucosa
What is the lamina propria in the oral cavity?
Dense collagenous tissue that supports the mucosa; composed of fibroblasts, WBCs, and collagen fibers
The lamina propria is divided into 2 layers. What are they and describe them?
Papillary Layer: superficial, loose CT with neurovasculature
Dense Layer: deep, dense irregular CT with large amounts of fibers
A sub-mucosa layer is present depending on location: comprised of loose CT, adipose tissue, and salivary glands
Where is the masticatory mucosa found?
Hard palate, gingiva, and dorsal surface of tongue
What is the masticatory mucosa made of?
Keratinized and/or parakeratinized stratified squamous epithelium
Describe the masticatory mucosa?
Nuclei are highly condensed and remain until the cells are exfoliated; highly interdigitated with rete ridges and papillae; thin or absent sub-mucosa
Where is the lining mucosa found?
Lips, cheeks, alveolar mucosal surface, floor of the mouth, inferior surfaces of the tongue, and soft palate
Describe the lining mucosa
Fewer rete ridges and connective tissue papillae; has distinct sub-mucosa
What is the lining mucosa made of?
Non-keratinized stratified squamous epithelium, but may be parakeratinzed in selected locations
The lining mucosa is divided into 3 layers. What are they and describe them
Stratum Basale: single layer of cells resting on basal lamina
Stratum Spinosum: several cells thick
Stratum Superficiale: most superficial layer of cells (surface layer of the mucosa)
Where is the specialized mucosa found?
Restricted to dorsal surface of the tongue
What is the function of the specialized mucosa?
Associated with sensation of taste
What is the specialized mucosa made of?
Keratinized stratified squamous covers muscular surface of the tongue; contains lingual papillae and taste buds responsible for gustation
What are the lingual papilla made of and describe them
Structures of keratinized epithelium with lamina propria; small, elevated structures of specialized mucosa, some of which are associated with taste buds
Describe the filiform papillae
Move food toward pharynx for swallowing; give dorsal surface of tongue velvety texture; shaped like fine-pointed cone; no taste buds
Describe the foliate papillae
Vertical ridges on lateral surface of tongue in more posterior regions; provide taste sensation
Describe fungiform papillae
Dorsal surface of tongue, found in lesser numbers; provide taste sensation
Describe circumvallate papillae
7-15 raised mushroom-shaped structures, anterior to sulcus terminalis; sunken appearance surrounded by trench; hundreds of taste buds present
What are taste buds?
Barrel-shaped organs that perceive food molecules; comprised of 30-80 spindle-shaped cells that extend from the basement membrane
What are the 5 taste sensations taste buds can have?
Sweet, salty, sour/acidic, bitter, and umami; each taste bud can discern all five tastes but appear to concentrate on 2 of the 5
Where are taste buds present?
Tongue, glossopalatine arch, soft palate, posterior surface of epiglottis, and posterior wall of pharynx
What are neruroepithelial (sensory) cells related to taste buds?
Elongated cells that extend from the basal lamina of the epithelium to the taste pore; will extend a microvilli through the pore; synapse with afferent sensory neurons of CN VII, IX, or X
What are supporting cells related to taste buds?
Elongated cells that extend from the basal lamina to the taste pore; contain microvilli on their apical surface and do NOT synapse with the nerve cells
What are basal cells related to taste buds?
Small cells located in the basal portion of the taste bud, near the basal lamina; stem cells for the 2 other cell types, supporting cells and neuroepithelial (sensory) cells
How often do we turnover taste buds?
About every 10 days
What are tonsils?
Large, irregular masses of aggregated lymphoid tissue; nodules typically dispersed singly in a random manner; can be partially encapsulated
What is the function of tonsils?
Protect against inhaled or ingested substances
Where are tonsils located?
Mucosa of posterior oral cavity, oropharynx, and nasopharynx
What are palatine tonsils made of?
Non-keratinized stratified squamous epithelium; densely populated with lymphocytes
Describe palatine tonsils
Possess 10-20 deep invaginations called tonsillitis crypts; dense CT acts as a partial capsule
Describe pharyngeal tonsils
Single structure, located on posterior wall of nasopharynx; covered with pseudostratified columnar ciliated epithelium; thin underlying capsule; invaginated mucosa with shallow infoldings but no crypts
Describe lingual tonsils
Positioned along base of tongue; covered with stratified squamous epithelium; possess germinal centers, varying numbers of crypts, and lacks a capsule
Teeth are divided into a crown and root. Describe both
Crown: projects into oral cavity and protected by enamel
Root: embedded in the alveolar ridge of an alveolus (tooth socket)
What is the bulk of the tooth made of (root and crown)?
Dentin
What is dentin?
Encloses central pulp chamber, containing pulp; composed of calcified organic matrix similar to that of bone; contains hydroxyapatite crystals
What is the root of the tooth invested by?
Thin layer of cementum
What are dentin all tubules?
Parallel tubes that radiate to the periphery of the dentin
What is enamel?
Translucent substance composed of parallel enamel rods (prisms) of calcium hydroxyapatite; rods are cemented together by an almost equally calcified interprismatic material
What is cementum?
Amorphous calcified tissue (calcium hydroxyapatite) into which the PDL (periodontal ligament) is anchored: covers the dentin in the root; thicker towards the apex of the root
What is the pulp?
Consists of loose, mesenchymal CT; collagen fibers, fibroblasts, mesenchymal stem cells; highly vascular, well-innervated; provides nutrition to dentin, can form reactive dentin due to chronic injury
What is the periodontium?
Consists of cementum, periodontal ligament, alveolar bone, and gingiva
What is the PDL?
Inserts into cementum and alveolar bone that lines the alveolus; comprised of collagen fibers
