Download Saliva secretion composition, function

Saliva secretion composition,
function
Saliva production
• From major paired salivary glands: parotid, submandibular, sublingual
• Parotid gland produces serous, watery, amylase-reach saliva
• Submandibular gland, produces mixed fluid from mucous and serous
acinar cells, saliva is slimy mucin-rich more viscous than former one
• Sublingual gland produces more viscous fluid mainly from mucous
acinar cells
Saliva production
• Minor salivary glands in oral mucosa produce mixed saliva apart
from lingual Ebner’s glands which are serous, and palatine which
are strictly mucous glands
They are found in many parts of the mucosa
They are named according to their location for ex.: labial, buccal
lingual, gloosopalatine glands
Saliva composition and related function
• 99% water
• 1% solids mostly proteins and elektrolytes
• Functions of saliva relate to both its fluid charakteristics and specific
components
• Fluid charakteristics: rinsing effect, solubilization of the food taste
substances, bolus formation, food and bacteria clearance, dilution of
detritus, lubrification, facilitation of mastication, swallowing, speech
• Specific components: protection of tooth structure by neutralization of
acids by buffering action, by maintaining supersaturated calcium
phosphate concentration, with regard to hydroxyapatite
amount
• Daily production of saliva is 0.5-1 l
• Unstimulated whole saliva flow-rate is 0.1-0.3ml/min
• Stimulated flow is 0.5-1.5ml/min
Xerostomia
• Xerostomia is related sensation of mouth dehydration
• Defined as subjective feeling of a sensation of oral dryness
• Impairs oral functions and even quality of life
hyposalivation
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Hyposalivation occurs when measured salivary flow rate
Stimulated is less than 0.5ml/min
Unstimulated is less than 0.1ml/min
Is a term based on objective measures of saliva production
Nearly always results in altered salivary composition
Oral symptoms of hyposalivation and xerostomia
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Mucosal dryness and soreness
Burning sensation of mucosa and tongue
Difficulties in speech
Difficulty in swallowing
Taste impairment
Difficulty in wearing removable dentures
Dry lips, angular cheilitis
Atypical caries pattern, carious lesions on smooth surfaces
Increased frequency of oral infections
Causes of hyposalivation
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Medication with side-effect of decline in the secretion rate
Polypharmacy
Radiation therapy to the head and neck region
Autoimmune diseases: Sjorgren’s syndrome, sarcoidosis
Menopause
Severe immune deficiencies AIDS
Depression
Diabetes mellitus type I
Salivary gland stones
medications
Antispasmodic, antidepressants, antipsychotic, parkinsonian,
arrhytmia medications, antihistamine, appetite depressants,
anticonvusant, anxiolytic, antihypertensive, diuretic,
skeletal muscle relaxants
Salivary clearance
• Dilutes
• Eliminates the substances introduced into oral cavity
Oral clearance after sugar consumption
• average residual volume of saliva after swallowing is 0.8ml
• The small amount of sucrose will dissolve in this residual volume of
saliva
• this will give rise to a very high sucrose concentration
• Taste of sugar with flavoring agents stimulates salivary glands to
produce saliva
• The volume of saliva will increase until maximum 1.1ml is reached
• It will induce swallowing [0.3ml] and clearing some of the sucrose
• when concentration of substance decreases the stimulation stops
• It results in slower clearing process
Oral clearence depands on
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Salivary flow rate
Volumes of saliva before and after swallowing
Characteristic of substance entering oral cavity
Place in the oral cavity: better clearing action occurs near the opening
of salivary duct
Buffering ability of saliva
• Carbonic acid/bicarbonate system
• Inorganic orthophosphate
• macromolecules
Hydrogen ion
• Is secreted via the salivary glands
• Produces by oral bacteria
• Taken into the oral cavity: acid drinks [pH of soft drinks and juices
ranges from 2.5 to 4]
Carbonic acid/bicarbonate system
• Most important buffering system
• Main buffering system in stimulated saliva
• Reduces the hydrogen ions with forming carbon dioxide which is
eliminated with breathing
Inorganic phophate
• In unstimulated saliva its concentration is nearly equal to carbonic
acid/bicarbonite system
• Together they take part in buffer capacity in unstimulated rate
Solubility of enamel
• hydroxyapatites pH 5.5
• Fluoroapatites pH 4.5
Lubrication, protection of oral mucosa
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Mucins which are mucous glycoproteins come from acinar cells
Have high molecular weight
Contain more than 40% of carohydrates
Named MG1, MG2
Are hydrophilic and entrain much water
Protective and reparative environment for teeth
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calcium ion has protective role toward mineral teeth structure
Statherin proline reach proteins PRPs
They bind calcium ion
creating stable supersaturated state of this ion in saliva
They inhibit spontaineous precipitation in saliva
Antimicrobial action
• Agregation of bacteria by agglutinins MG1,MG2, beta 2
microglobulin, fibronectin, the bacterial aggregats are easly removed
from oral cavity by swollowing
• Breakege of bacterial wall, by hydrolyzing enzyme which is the part of
lysozyme
• Lactoferrin- an ion-binding protein, takes iron [Fe+3]from
microorganisms, thus provides antimicrobial action
• Antimetabolic activity against several microorganisms perform
salivary peroxidase and myeloperoxidase
• Competitive inhibition of bacterial adhesion to enamel
Mg1,MG2, Statherin, PRPs
Immunoglobulins
• IgG-enhancement of phagocytosis
• IgM- enhancement of phagocytosis
Pellicle
• Saliva is separated from tooth surface by thin layer of biofilm called
aquired pellicle
• Is defines as acellular layer of adsorbed salivary proteins and other
macromolecules on the dental enamel surface
• Approximately 10 micromiters thick
• Protects the enamel against abrasion and attrition, also serves as
diffusion barrier
• Forms the base for subsequent adhesion of microorganisms
• Is then termed dental plaque
Pellicle – functions:
• Adsorption of the proteins mainly originated from saliva is selective
• certain macromolecules show higher affinity for the mineral structure
• The enamel surface is charged negatively in normal pH, thanks to
strucutre of hydroxyapatites
• Ions of opposite charge e.g.calcium, sodium, pottasium, chloride are
attracted to the surface, forming a hydration layer,
• The charge of enamel with its hydration layer is positive
• Will attract negatively charged macromolecules
• Selective attachment of bacteria to the enamel surface is achieved
when the surface characteristic (adhesins) of bacterium fit with
component in the pellicle (receptors)