L28. oral cavity Flashcards
What does the digestive system consists of
- oral cavity
- alimentary canal
- accessory glands
What are the functions of the bolus
- mastication (chewing)
- swallowing /deglutttion
- bolus formation
- ingestion /taste
What are the 3 compoents of the lips?
- external
- intermediate/vermillion
- internal
Describe the external aspect of the lips
- continuous with the skin
- keratinizes stratified squamous epithelium
Describe the intermediate vermillion section of the lips?
- highly vascularized lamina propria
2. no hair, sweat , sebacous glands
Describe the internal aspect of the lip
- continuous with the cheek (same histology)
1. epithelium: non-keratinized stratified squamous epithelium
2. lamina propria: dense irregular CT.
3. submucosa: contains mucous gland which keeps lips moistened
4. adventitia: skeletal muscles (orbicularis oris muscles) continuous with gums ( gingiva)
Describe the gingiva
- gums
- forms a bacterial barrier around the roots of the teeth
- junctional epithelim protects the periodental ligament by acting as a bacterial barrier
- lamina propria mingles with the periodental ligament and fuses tooth with bony sockets
Describe the epithelium of the gingiva
slightly keratinized stratified squamous epithelium
Describe the mucosal layer of the gingiva
dense irregular connective tissue contains a lot of collagen 1 fibers
Describe the adventitia layer of the gingiva
bone ( maxilla: upper ;mandible: lower)
Describe bacterial gingivitis ( redness of the gum)
due to inflammation of the lamina propria layer
if untreated: periodental ligament: collagen 1 fibers anchor the teeth to the underlying gum line
When does tooth formation begin
6 week of gestation
What are the components of the tooth
- enamel
- dentin
- pulp cavity
Describe the enamel
- 95% hydroxapetite crystals /mineralized
- non-regenerative (non-vital) once degraded by bacteria ( cavity) cannot be re-formed
- formed by ameloblast (on outer surface of tooth: dies after teeth erupts)
Describe dentin
- minearlized 70% hydoxyapetite
- regenerative
- pain if injured
- produced by odontoblast on the inner surface of the tooth lining in pulp chamber
Describe the pulp chamber
- nerves and vessles enter and exit the narrow space
- loose CT and high GAG content
- highly vascularized and innervated
Where are ameloblast derived from
oral ectoderm/ dental placode
Where are odontoblasts derived
mesoderm
Describe odontogenesis
- INDUCTION: dental placode forms above the mesnchyme and there are paracrine signaling factors (SHH and BMP) exchanged between the dental placode and the mesenchyme layer. induces differentiation and the dental placode sinks into the mesenchyme
- MORPHOGENESIS: placode sinks to form a folded cap (enamel organ gives rise to the ameloblast that forms enamel). mesenchyme forms odontoblast . pulp forms from mesenchyme. mesenchyme differentiates to form the periodontal ligaments besides the oral ectoderm and cementoblasts
- DEVELOPMENT: ameleoblasts die after the tooth erupts, enamel is revealed
Describe the crown of the teeth
2 types anatomical and clinical
- anatomical: portion of tooth covered by the enamel
- clinical: enamel above the gingiva (visible portion of teeth)
- anatomical crown:anatomical crown is surrounded by junctional epithelium from the gingiva -> protects against pathogenic invasion
Describe the periodental ligament
- highly vascularized
- highly innervated
- mesodermally derived
- collagen 1 fibers embed the spongy bone and the cementum (collagen 1 fibers radiate into the lamina propria of the gingiva)
Describe the alveolus
socket of spongy bone in the mandible and maxilla
Describe the cementum
- directly attached to the outer aspect of dentin
- bone-like and produced by cementoblast (like osteoblast)
- resorbed by cementoclast ( like osteoclast)
Describe the palate
- roof of the oral cavity
- separates the nasal and oral cavities
- hard palate is located anteriorly and the soft palate is located posteriorly
Describe the hard palate
- keratinized stratified squamous layer
- adventitia contains bone
Describe the soft palate
- non-keratinized stratified squamous layer
- contains skeletal muscles -elevates the soft palate during swallowing to prevent food from going upwards to the nasal cavity
- elevates uvula during swallowing to close nasal cavity
Describe the tongue
- floor of the oral cavity
- contains papillae
- consists of keratinized stratified squamous keratinized epithelium and a core lamina propria. contains dense irregular connective tissue
- lamina propria (posterior aspect) contains MALT: lingual tonsiles
- serous glands are prominent in the submucosa; secretions from these glands trap tastant molecuels that can stimulate dendritic microvili of sensory receptors
What is papillae
mucosal specializations
are lymphoid nodules basophilic or acidophilic
basophilic
Where are lingual tonsiles (lymphoid nodules) found
lamina propria of tongue papilia
Describe the taste buds
- found in the epithelium
- spindle shaped sensory cells with dendritic microvili protruding apically from taste pore
- tastants dissolved in the serous fluid bind to G-protein coupled receptors and ion channels on the microvili
- downstream signals stimulate synapse like release and activation of afferent sensory neurons
