lecture 15/16 Flashcards
oral cavity (GI1)
which organs/tissues are included in the digestive system?
digestive tract:
* oral cavity
* pharinge
* esophagus
* stomach
* small/large intestine
* rectum
associated glands:
* salivary glands
* liver
* pancrease
what is the function of the digestive system?
obtain, from ingested food, the metabolites for growth and energy requirments, and bepfre being stored or used as energy, it must be digested and transformed into small molecules that cna be absorbed through the lining of the GIT
what is the first step of digestion?
- occurs in the mouth
- food is moistened by saliva and ground by the teeth into smaller pieces
- saliva also initiates the digestion of carbohydrates
classify the epithelium lining the oral cavity
nonkeratinized stratified squamous epithelium
what is special about the epithelium on the lips?
a transition from keratinized to nonkeratinized can be seen
is the gingiva keratinized?
it is parakeratinized
is the external lip keratinized?
it is orthokeratinized
the tongue is a mass of _______ muscle covered by a layer of ______
striated; oral muscosa
classify the mucosa of the tongue
nonkeratinized stratified squamous epithelium
why is the dorsal surface of the tongue irregular
b/c of presence of smal eminencies called papillae
what are the different types of papillae?
- filiform
- fungiform
- circumvallate
what type of gland is found near circumvallate papillae?
von ebner gland
what type of gland are von ebner glands?
serous
what do von ebner glands secrete?
lipase, which is active in the stomach
what different cells are seen in a taste bud?
- supporting cells (type I) – are dark
- sensory cells (type II) – are pale
- type III cells (intermediate cells)
- basal cells (type IV) – stem cells
type I and II have micorvilli which cause depolarizaton when coming in contact with food - afferent fibers with schwann cell
what are the different human tase perceptions?
- saltiness
- sweetness
- sourness
- bitterness
- umami
where can we find taste buds?
- palate
- circumvallate papillae
- a couple in fungiform papillae
function of salivary glands
- to wet and lubricate the oral cavity and uts content
- to initiate the digestion of carbohydrates
- to secrete amylase, lysosyme, IgA, and lactoferrin
what are the different types of salivary glands?
also, are they serous or mucous
- parotid (mainly serous)
- submandubular (serous and mucous)
- sublingual (mucous)
what is the shape of salivary glands?
compound acinar
difference between the serous and mucous acini?
- serous: pyrymidal, acidophilic, small lumen, myoepithelial cells, zymogenic granules that secrete thiner proteinaceous secretions
- mucous: bigger, stain pale, nucleus at the base, bigger lumen, prodcue mucin
difference between striated and intercalated ducts?
- striated: have striations (deliniated cells), more organized
- intercalated: generally smaller (nuclei will seem bigger), less organized
diphyodonty
having two sets of teeth
how many baby and adult teeth do we have?
20 baby and 32 adult
what are the 2 dental arches?
the upper (maxillary) and lower (mandibular)
what is enamel made of?
99% inorganic matrix (hydorxyapatite crystals), and 1% proteins (enamelins, amelogenins) and water
what is dentin made of?
70% inorganic matrix (hydorxyapatite crystals), 30% organic matrix (protein and proteoglycans – collage type I)
what are two ways to decalcify?
5% nitric acid or 250 mM EDTA
classify the periodontal ligament
dense regular CT
what are sharpey’s fibers?
collagen type 1 fibers that go into the cementum from the periodontal ligament
what is the budd stage of teeth developemnt?
- neuro-ectoderm cells migrate from the neural crest
- the neuro-ectoderm cells induce the formation of epithelial tooth bud (10 future baby or deciduous teeth)
what is the early cap stage of teeth development?
- the epithelial structure (oral ectoderm) will form the future enamel organ
- the neuro-ectoderm cells mix with mesoderm cells and form the neural crest mesoderm
what is the late cap stage of teeth development?
- the future enamel organ remain connected to the oral ectoderm by the dental lamina and originiate a second bud for the permanent tooth
- the cells of the enamel organ differentiate into defined layers (outer and inner dental epithelium)
- some cells of the neural crest mesoderm (mainly neuro-ectoderm cells) start differnetiating inot odontoblasts
what is the bell stage of teeth development?
- in addition to the ODE and IDE, the enamel organ differentiates into stratum intermedium and stellate reticulum
- the IDE is formed by ameloblasts which synthesize enamel. the crown shapes at the bell stage
- the cervical loop marks the position of the neck of the tooth (crown-root junction)
- the odontoblast become aligned and the primitive dental papilla (future pulp) is formed
what is the root formation stage of root development?
- the junction bwn the IDE and odontoblasts mark the dentino-enamel junction. from this point the odontoblasts grow inwards and IDE does not form enamel in this region and instead recuits odontoblasts
- the ODE and IDE disappear (apoptosis) and the odontoblast induce the mesenchyme to form cementoblasts and cementum
- the forming tooth is within a pocket of alveolar bone. and bwn the bone and cementum, the periodontal ligament is formed
the baby tooth functions until 5-6 years of age, and permanent teeth develop the same way - odontoclasts (osteoclastst) erode the root of the baby tooth and the new permanent tooth grows as the root of the baby tooth is eroded
