the oral environment Flashcards
state the oral fluids
saliva, gingival crevicular fluid, oral bacteria, food debris and epithelial cells
what are the 2 main functions of oral fluid?
protective and digestive
in which ways does the oral fluid perform a protective function?
cleansing, mucosal protection, buffering, remineralisation, antimicrobial
in which ways does the oral fluid perform a digestive function?
digestive enzymes, lubricates bolus for chewing and swallowing
what may a reduced saliva flow cause?
caries in abnormal places (buccal and labial area), xerstomia
name the 3 major pairs of salivary glands glands
parotid, sublingual and submandibular
where are the minor salivary glands located?
buccal, labial, lingual, palatal
what are the basic secretory units of salivary glands?
clusters of cells called acini
which duct leads directly from the acini of salivary glands?
intercalated duct
which duct leads directly from the intercalated duct?
striated duct
where is all saliva produced by salivary glands gathered?
collecting duct
which major salivary gland produces mixed secretions?
submandibular
which major salivary gland produces serous secretion
parotid
which major salivary gland produces mucous secretion
sublingual
which minor salivary glands produce mucous secretion
buccal, labial, lingual and palatal
which minor salivary gland produces serous and mucous secretions?
lingual
where is gingival crevicular fluid produced?
the epithelium lining gingival crevice
what may gingival crevicular fluid also be called?
secular fluid
what increases the flow of gingival crevicular fluid?
inflammation (gingivitis)
what is the average daily salivary flow?
500-700ml
which salivary gland is the major contributor when sleeping?
submandibular
which salivary gland is the major contributor when awake?
submandibular
which salivary gland is the major contributor when stimulated?
parotid
which factors affect unstimulated salivary flow rate?
state of hydration, previous stimulation, circadian and circannual rhythms, medication and salivary gland disease
what are the inorganic components of saliva and their % composition?
water (99.5%), ions (0.2%)
what are the organic components of saliva and their % composition?
mainly proteins (0.3%) and very little carbohydrates or lipids
which buffering ion concentration is greater at higher salivary flow rate?
bicarbonate
which ions are present in saliva?
fluoride, calcium and phosphate, thiocyanate, bicarbonate, phosphate
what is the function of the fluoride ion in saliva?
antibacterial, forms fluoroapatite, promotes remineralisation
what is the function of the calcium ion in saliva?
remineralisation
what is the function of the bicarbonate ion in saliva?
buffering
what is the function of the phosphate ion in saliva?
remineralisation and buffering
what is the function of the thiocyanate ion in saliva?
antibacterial
what are the salivary buffers?
bicarbonate, phospahtes, proteins, bacterial ammonia
describe the series of events that occur in acini cells to produce saliva
. increase in calcium opens calcium dependant potassium and chloride ion channels
. chloride ions cross the apical membrane into lumen of acinus
. sodium follows chloride across cell to maintain electroneutrality
. resulting osmotic gradient moves water
name the 13 main salivary proteins
amylase, lipase, cystatin, gusting, statherins, histatins, immunoglobin, lactoferrin, lactoperoxidase, lysozyme, plasma proteins, proline-rich proteins, mucoproteins
what type of protein is amylase?
enzyme
which 2 ions does amylase require?
chloride and calcium
what is another name for the lysozyme proteins produced in saliva?
muramidase
what is the general role of salivary amylase?
defence
what is the general role of salivary lysozymes?
non-specific defence
how do lysozyme carry out defence?
attack bonds in bacterial cell walls causing lysis
what is another name for lactoperoxidase in saliva?
sialoperoxidase
what type of protein is sialoperoxidase (lactoperoxidase)?
enzyme
what does lactoperoxidase in saliva do?
releases oxygen from hydrogen peroxide, and allows oxidation of thiocyanate to orodcude hypothiocyanate
which bacteria are intolerant to oxygen?
obligate anaerobes
what is the function of hypothiocyante?
antibacterial action
what do cystatins in saliva do and what is their function?
inhibit cysteine proteases, antimicrobial function
what are cysteine proteases?
proteins which breakdown proteins on amino acid cysteine side chain
which molecule does gustin require to function?
zinc
what is the function of the salivary protein gustin?
facilitate taste function by activating taste buds, produce bicarbonate buffer
what does the salivary proteins histatin do?
. inhibits calcium phosphate precipitation (calcium phosphate precipitation forms calculus) by allowing super saturation of calcium phosphate
. antimicrobial
. inhibits candida albicans and strep mutans
what compound is hydroxyapatite made from?
calcium phosphate
what type of protein molecules are immunoglobins?
antibodies
give an example of an immunoglobin?
IgA
which salivary protein has a short memory?
immunoglobin
what is the function of salivary immunoglobin?
specific immunity against bacteria
which salivary protein binds to iron?
lactoferrin
what is the function of lactoferrin?
takes away iron from oral environment and therefore from iron-requiring bacteria, antibacterial
where in the mouth is iron found?
gingiva
describe the structure of mucoproteins
polypeptide backbone with polysaccharide side chains
what do salivary mucoproteins do?
. bind to tooth and epithelial surfaces, when it binds conformation changes allowing more bacteria to bind . protective role . lubricative role . forms primary pellicle . promotes bacterial aggregation
what is the primary pellicle?
protein film on surface of enamel formed by selective binding
what is the function of salivary proline-rich proteins?
adsorb onto hydroxyapatite:
- acting as diffusion barrier
- decreasing mineral loss
- resist acid attack
- allow mineralisation
what is the function of salivary statherins?
. prevent precipitation of calcium phosphate by super saturation
. maintain high Ca for remineralisation and PO4 for buffering
. anticalculus action
give examples of plasma-derived proteins which have spilled over
proteins, blood group substances, ummunoglobins, hormones, drugs
name the 9 antimicrobial salivary proteins
cystatins, histatins, amylase, immunoglobin, lactoferrin, lysozyme, mucoproteins, lactoperoxidase, proline-rich proteins
name the 2 buffering salivary proteins
gustin, statherins
name the 3 digestive salivary proteins
amylase, lipase, lysozyme
name the lubricating salivary protein
mucoprotein
name the 2 remineralising salivary proteins
proline-rich proteins and statherins
what to responses control the secretions of saliva?
unconditioned and conditioned responses
define unconditioned responses
unlearned, innate
define conditioned responses
learned, acquired y association
what are the 2 types of conditioned responses that produce saliva?
mechanical and chemical
describe how saliva is produced by mechanical stimuli
. pressure on PDL/oral mucosa stimulates saliva from ipsilateral gland
describe how saliva is produced by chemical stimuli
gustation (tasting) or olfaction or common chemical sense triggers saliva
what does ipsilateral mean?
gland on same side
what is common chemical sense?
privative response to irritants or injury, mediated by nociceptors (respond to damage) in mucous membranes, contribute to taste of spices
what effect do parasympathetic nerves have on salivation and blood flow?
increased blood flow and salivation
what effect do sympathetic nerves have on salivation and blood flow?
increased salivation, decreased blood flow
name the 2 mechanism of salivary secretion
primary secretion in acinus and secondary modification in striated ducts
which cells secrete primary saliva
acini
which ducts modify saliva?
striated ducts
how is saliva modified by striated ducts?
bicarbonate and potassium secreted into saliva and sodium and chloride removed
what is saliva in relation to plasma?
hypotonic
how is bicarbonate formed?
CO2 + H2O in the presence of carbonic anhydrase
approximately how much saliva is in the mouth?
1.1ml
is the saliva film in motion or static?
motion
where is saliva film velocity flow lowest?
labial, buccal regions
where is saliva film velocity flow highest?
lower, lingual areas
how does saliva film velocity influence the incidence of caries?
cariogenic sugars are retained longer in regions where flow is lowest
where is the mouth is caries most common?
upper, labial regions
where is the mouth is calculus most common?
lower lingual regions
define incidence
no. within period of time
define prevalence
overall amount
define clearance
rate at which substances are removed from the mouth
in which 2 ways is clearance important for oral health?
. removal of harmful substances
. retention of beneficial substances
how is removal of harmful substances increased?
high salivary flow rate
how is retention of beneficial substances improved?
low salivary flow rate
how do micro-organism generate acid?
metabolising sugars
what is a stephans curve?
a graph of the plaque pH change over time
what is occurring when plaque pH drops to a critical level?
demineralisation
at what pH are teeth remineralised?
approx pH 5.5
which bacteria species likes acid?
streptococci mutans
what is the main benefit to our oral health of chewing gum?
increases salivary flow
how does gum increase salivation?
stimulates mechanoreceptors on PDL
how does gum neutralise plaque acid?
increases bicarbonate content of saliva
why are sweetners not bad for our oral health?
they are not metabolised to acid by plaque bacteria
name some bulk caloric substances?
sucrose, fructose, glucose and lactose
are bulk caloric substances cariogenic?
yes
name some non-caloric/high-intensity sweetners
aspartame, cyclamates, saccharin, sucralose
name some low caloric sweetners
mannitol, sorbitol, xylitol
patients complain of dry mouth when salivary flow drops below?
50%
a reduction in salivary flow by 50% requires loss of what?
function of more than 1 major salivary gland
what may cause xerostomia?
side effect of drugs, radiotherapy, diseases
how does radiotherapy cause xerostomia?
it damages glands and epithelia
what may reduced salivary flow cause?
caries, oral disease, dysaesthesia, impaired oral function, diminished taste perception
what is the clinical name for burning mouth?
dysaethesia
what is caused as a result of reduced clearing?
loss of protective function
what can be used to treat xerostomia with functioning gland tissue?
drugs, chewing gum
what can be used to treat xerostomia with no functioning gland tissue?
saliva substituem containing mucins or cellulose