physiology of the mouth and oesophagus Flashcards
what are the 3 pairs of salivary glands
parotid
submandibular
sublingual
how much saliva secreted each day
1500ml
what does saliva contain
- mucous to help lubricate food
- a-amylase to initiate breakdown of carbohydrate
- lysozyme (antibacterial actions)
what is the formation of saliva
- isotonic fluid is produced by acinar cells, they secrete electrolytes and water
- fluid is modified as it flows along salivary duct
- final composition depends upon flow rate and neuronal input
what controls saliva secretion
reflexes mediated via ANS
what type of saliva does the parasympathetic system produce and how does it impact blood flow
- watery saliva
- rich in amylase and mucous
- increased blood flow to glands
what type of saliva does the sympathetic nerve produce and how does it influence blood flow
- promotes increased output of thicker mucous
- reduces blood flow to glands
what happens during the voluntary stage of swallowing
the tongue pushes bolus backwards to orthopharynx
what happens during the pharyngeal stage of swallowing
- soft palate and uvula move up to seal off nasopharynx
- larynx raised and the glottis is sealed
- epiglottis covers glottis and breathing is suspended for 1-2secs
what controls the pharyngeal stage of swallowing
it is a reflex action controlled by deglutition centre in medulla and pons of brain
what type of muscle is the first third of the tube that connects the laryngopharynx to the stomach
the muscularis layer striated to assist in swallowing
what is the middle third of the tube that connects the laryngopharynx to the stomach
a mix of striated and smooth muscle
what is the lower third of the tube that connects the laryngopharynx to the stomach
all smooth muscle
what needs to be considered when using buccal route
- drug must dissolve in saliva so hydrophobicity is an issue
- need to consider swallowing reflex for buccal delivery - retention in mouth important
- surface area for absorption is limited 200cm vs 20,000cm (skin)
characteristics of oral mucosa
- surface area is limited
- passive diffusion
- rich blood supply - rapid onset of action with similar bioavailability to iv formulation
barriers to oral delivery
- drugs must diffuse across lipophilic cell membrane and hydrophilic interior of cell
- enzymatic barrier in buccal tissue also exists causing rapid degradation of peptides and proteins (limits transport across epithelium)
challenges of buccal delivery
- barriers
- drug must be kept in place for absorption. excess saliva could reduce this
- surface area limited
- taste of drug must be bland
- drug must be non irritant to mouth or teeth
what can dry mouth cause and what can it affect
oral ulcers and dental caries.
can affect digestion and drug absorption.
how can dry mouth be treated
with artificial saliva preparations (lozenge/spray/gel)
how are oral ulcers treated
they usually clear up w/o treatment
sometimes require anti-inflammatory and antimicrobial mouthwash to prevent infection
what causes oral thrush
- overuse of antibiotics
- poor immune system
- underlying disease
- smoking
- dentures
how is oral thrush treated
treatment is aimed at reducing fungal infection using oral anti-fungal gel
eg miconazole
how do antacids cause tooth decay
may contain sugar or artificial sweeteners
chewable antacids can get stuck between your teeth and over time can result in decay
how can pain medications cause tooth decay
opioids can cause dry mouth and the consequent erosion of tooth enamel
