Ingestion Of A Meal Flashcards
What muscles are used in closing the mouth?
Temporalis and massester
Describe the temporalis muscle
Arises from the temporal fossa and inserts onto the coronoid process of the mandible
Describe the masseter
Arises from the zygomatic process of the maxilla and inserts into the angle and ramus of the mandible
Which muscles open the mouth?
Lateral pterygoid, digastric and infrahyoid
Describe the lateral pterygoid
Arises from the sphenoid and inserts onto the condyloid process of the mandible
Describe the digastric muscle of mastication?
Posterior; arises from the mastoid notch
Anterior; arises from the lower border of the mandible
Inserts onto the hyoid
Describe the infrahyoid muscles of mastication
4 pairs of muscles, arise from hyoid and insert onto clavicle
What controls mastication?
Brain stem pattern generator
Fine tuning via sensory feedback through periodontal ligaments and proprioceptors
Change in occlusion will change chewing pattern
What are the 3 movements of mastication?
The temperomandibular joint (TMJ) allows three movements of mastication: open/close; protrusion/retraction; lateral
What activates salivation?
Mastication, taste, smell, anticipation
What inhibits salivation ?
Fear
Where are salivary nuclei activated?
Superior (pons)
Where are salivary nuclei inhibited?
Inferior ( medulla )
Which salivary glands are activated and by what carnival nerve?
Submandibular sublingual salivary glands activated by cranial nerve VII
Which salivary glands are inhibited and by what cranial nerve?
Parotid by cranial nerve IX
What are the functions of saliva?
Tooth maintenance
Lubrication: allows speech, mastication and deglutition
Antibacterial/antifungal
Digestive; salivary amylase; lingual lipase
What are the muscles of mastication innervated by?
The mandibular branch of the trigeminal nerve
What control are the muscles that move the mandible under?
Voluntary
What are the reflexes of the jaw?
Jaw unloading reflex and jaw jerk reflex
What are the main functions of saliva in preserving the teeth?
Dilution, clearance and buffering
What happens on the Stephan curve?
Plaque pH plummets from 7 to about 5 before climbing back up - sugar had been added
ph less than 5.5 teeth demineralise due to acid produced by bacteria
Saliva dilutes the sugar
Clear it by swallowing
Saliva has bicarbonate in it to neutralise the acid
How does saliva lubricate?
Salivary glycoproteins are sticky and move freely in a plane rubbing over each other side to send, but don’t move upwards
Make a thin film to coat all oral surfaces and food
Describe the oral/buccal phase of deglutition?
Voluntary
The bolus is pushed to the back of the mouth by the tongue
The teeth are brought together
The soft palate elevated to close the nasal cavity
The larynx rises to close the airways
(Inspiration is inhibited)
Describe the pharyngeal stage of deglutition
Involuntary (reflex)
cricopharyngeal sphincter relaxes to open the oesophagus
The epiglottis steers the bolus over the trachea and the peristalsis starts
Describe the oesophageal phase of deglutition
Peristalsis takes food down towards the stomach
All of changes in the oral / buccal and pharyngeal phases reverse
What is the function of amylase?
Breaks down starch
How is saliva antibacterial/antifungal?
Protection barrier
Secretory IgA
Lysozyme
How many pairs on salivary glands are there and what are they called?
3 pairs
Parotid - biggest by ear
Submandibular - under and further back from tongue
Sublingual - under the tongue
What type of saliva do parotid glands produce?
Serous
What type of saliva do sublingual glands produce?
Mucous
Good for giving resting saliva
What type of saliva do submandibular glands produce?
Mixed serous and mucous
What type of saliva do minor glands produce?
Mucous
What do all salivary glands secrete?
Both protein and fluid
What is the consistency of saliva determined by?
The nature of the secreted protein
What are the cells that produce saliva called?
Acinar cells
What are the 2 types of acinus cells?
Serous acinus and mucous acinus
Why does Mucinus acinus stain more heavily than serous acinus cells?
Has more glycoprotein
What does saliva produced by acinus cells pass down?
Intercalated duct
Striated duct
Excretory duct
Where is the nucleus located in acinar cells?
Basolateral or blood side
What does the acinar contain?
Nucleus, endoplasmic reticulum, secretory vesicles
What 2 things do you need for saliva?
Protein and fluid
What is the secretion of protein in saliva regulated by?
Secondary messenger cAMP cyclic adenosine monophosohate
What is fluid secretion in saliva regulated by?
Calcium
What regulates cAMP production?
Sympathetic nervous system
Noradrenalin
What regulates Ca2+ secretion
Parasympathetic nervous system
Acetylcholine
What happens when noradrenaline binds to the beta adrenergic receptor?
Activates receptor
Activated receptor activates alpha subunit of G protein which then activates adenylate cyclase
Adenylate cyclase takes ATP and turns it into cyclic AMP
What does cyclic AMP do in acinar cells?
Diffuses into the nucleus where it switches on protein transcription
Causes maturation of the proteins and the formation of secretory vesicles
Stimulates exocytosis in acinar cells
How does IgA get from the blood to the saliva?
Receptors for IgA on the basolateral membrane
Bind the IgA
IgA is internalised and crosses the cell in the vesicles then exocytose off in the apical membrane
What receptor does IgA bind to?
Polymeric immunoglobulin receptor
PIgR
What receptor is involved in fluid secretion?
M3 muscarinic receptor
What happens when M3 muscarinic receptor is activated?
Activated by acetylcholine
Causes activation of phospholipase C
Phospholipase C makes IP3
What does IP3 do?
Releases calcium from the endoplasmic reticulum
Ca2+ increases in acinar cells
Ca2+ depended ion channels on membrane
Apical - chloride and basolateral K+ move out of cell
Creates charge imbalance across tissue
Drags sodium between cells
Moves salt from basolateral side to to apical side
Creates and osmotic gradient
Moved fluid
What happens if salivary glands aren’t working?
Opportunistic infections eg Candida infection
Rampant caries
What is xerostomia?
Dry mouth
What causes xerostomia?
Analgesics
Anti hypertensives
Anti depressants
Anti histamines
