4. Ingestion Of A Meal Flashcards
Muscles of mastication
(For opening -3- vs closing -2-)
Innervation
Opening:
-lateral pterygoid (sphenoid to condyloid process on mandible)
-digastric (post from mastoid notch to hyoid; ant from inf mandible to hyoid),
-infrahyoid (4 pairs hyoid to clav)
Closing:
-masseuter
-temporalis
Innervation: mandibular branch of trigeminal nerve (CNV)
Control of jaw
- 2 reflexes and describe
- Fine tuning control
- Jaw opening reflex (stimulate lips, oral mucosa or teeth, inhibit mandible elevators wo contraction of depressors); jaw jerk reflex (tap on front of chin when mouth slightly open, jaw relaxed/tongue blade placed on lower teeth&tapped—>temp & mass to contract)
- Via sensory feedback through periodontal ligaments (attach tooth to alveolar bone) and proprioceptors (receptor for position and movement-this one for teeth)
3 movements of mastication
Hinge
Protrusion/retraction
Lateral grinding
- Stimulator/inhibitor of salivation
- General route for control of salivation
3 & 4: 2 routes of control of salivation (nervous mechanism)
Stimulators: mastication, taste, smell, anticipation
Inhibitors: fear/fight or flight response
General route: stimulus>salivary nuclei>salivary glands
Route 1: stimulate>superior sal. nuclei (pons)>CNVII(facial)>submandibular and sublingual glands
Route 2:
Stimulate>inf sal nuclei (medulla)>CNIX(glossopharygeal)>parotid gland
Main functions of saliva (4)
Tooth maintenance
Lubrication
Antibac/antifungal: protective barrier; has secretory IgA and lysozyme
Digestive: salivary amylase; lingual lipase (less important)
- Functions of saliva in tooth maintenance
(3) - Critical pH of teeth and what happens if too much acid
- Tooth maintenance:
a)dilution of sugar;
b) clearance/swallowing of sugar and bacteria;
c) buffer (high conc of HCO3- to neutralise acid) - 5.5
If more acidic, demineralise (Ca2+ comes out of teeth)
Func of saliva regarding lubrication
Constituents and how it works
Allows speech, mastication and deglutition
Made up of salivary glycoproteins
Stick together
side chains entangle and move side to side and not really up/down
make film over oral surfaces/food>lubricate for mastication and deglutition
Salivary Gland (4), type of saliva (3), nature of saliva
- Parotid; serous/watery; good for thinning saliva & neutralising (lots of HCO3-)
- Sublingual; mucous; resting saliva
- Submandibular; mixed; resting saliva, responds well to stimuli
- Minor glands; v mucous lots of GP; keep mouth lubricated during sleep
All salivary glands secrete protein and fluid, constituency depend on nature of saliva
Draw a salivary gland
Draw acinar cell
What do they secrete?
Gland:
- Acinar cell (serous or mucous acinus or both depending on gland type)
- myoepithelial cell
- serous demilune
- intercalated duct (towards acinar)
- striated duct (middle of gland
- excretory duct (bottom of gland)
Acinar cell (polarise): -Basolateral/blood side-> outside of gland -Apical/lumenal -Basally located nucleus -ER -Secretory vesicles Secrete protein and fluid
Stimulus secreting coupling: describe secretion of protein in acinar cell
- Noradrenalin stimulate beta adrenergic receptor
- Alpha sub unit of G protein dissociate
- Activates Adenylate cyclase (AMP>cAMP)
- cAMP diffuse into nucleus
- result in gene transcription (of secretory proteins); glycosylation (mature the protein); formation of secretory vesicles and exocytosis of vesicles
Note usually Ca2+ 2nd msger for exocytosis but this time is cAMP
Describe secretion of IgA (acinar cell)
Not all protein made by acinar cells E.g. IgA therefore req transcellular translocation:
- IgA attach to PIgR (polymeric immunoglobulin receptor)
- PIgR and IgA internalised
- Move across cell
- Exocytosed
Note: can tell IgA secreted bc still connected to some of PIgR
Describe fluid secretion (acinar cell)
- Acetylcholine attach to M3 muscarinic receptor
- G protein activates phospholipase C
- IP3 produced
- Cause Ca2+ release from ER
- Ca2+ activates Ca2+ dependent ion channels: K+ on blood side and Cl- on lumenal side
- Charge imbalance across cell makes Na+ move into lumen of gland (NaCl made on apical side)
- Osmotic grad causes water to move with NaCl
Note: molecule outside cell=1st msger; inside=2nd msger
- Dry mouth medical name
2. Causes (3)
- Xerostomia
- Many drugs are xerogenic (make sure to let patient know of side effect as may result in rotten teeth)
- Radiotherapy for head & neck cancers
- Disease: Sjögren’s syndrome (autoimmune-so mostly post menopausal women; salivary gland atrophy/dysfunction;2ndary condition to rheumatoid arthritis and lupus)
