saliva
DESCRIPTION
SALIVA. Seminar Stomatology. MAJOR FUNCTIONS OF SALIVA. Solvent Buffering Lubrication Remineralization Digestion Anti-bacterial Anti-fungal Temperature regulation Production of growth factors and other regulatory peptides. A CONSIDERABLE VOLUME OF SALIVA IS PRODUCED OVER A DAY. - PowerPoint PPT PresentationTRANSCRIPT
SALIVA
Seminar
Stomatology
MAJOR FUNCTIONS OF SALIVA
Solvent Buffering Lubrication Remineralization Digestion Anti-bacterial Anti-fungal Temperature regulation Production of growth factors and other regulatory
peptides
A CONSIDERABLE VOLUME OF SALIVA IS PRODUCED OVER A DAY
0.5 to 1.5 liter of fluid is secreted in a day This represents about 1/5 of the total plasma
volume This fluid is not lost as most of it is swallowed
and reabsorbed by the gut Parotis, submandibularis, sublingualis
THE SECRETORY UNITThe basic building block of all salivary glands
ACINI - water and ions derived from plasma
Saliva formed in acini flows down DUCTS to empty into the oral cavity.
TWO STAGE HYPOTHESIS OF SALIVA FORMATION
Water & electrolytes
Isotonic primary saliva
Most proteins
Some proteins electrolytes
Na+ Cl- resorbed
K+ secreted
Hypotonic final saliva into mouth
Inorganic components
Saliva compositon
Calcium and phosphate Help to prevent dissolution of dental enamel Calcium
1,4 mmol/l (1,7 mmol/l in stimulated saliva) only cca 50% in ionic form sublingual > submandibular > parotis
Phosphate 6 mmol/l (4 mmol/l in stimulated saliva) 90% in ionic form
pH around 6 - hydroxyapatite is unlikely to dissolve
Increase of pH - precipitation of calcium salts => dental calculus
Hydrogen carbonate
Buffer Low in unstimulated saliva, increases with
flow rate Pushes pH of stimulated saliva up to 8 pH 5,6 critical for dissolution of enamel Defence against acids produced by
cariogenic bacteria Derived actively from CO2 by carbonic
anhydrase
Other ions Fluoride
Low concentration, similar to plasma
Thiocyanate Antibacterial (oxidated to hypothiocyanite OSCN- by
active oxygen produced from bacterial peroxides by lactoperoxidase)
Higher conc. => lower incidence of caries Smokers - increased conc.
Sodium, potassium, chloride Lead, cadmium, copper
May reflect systemic concentrations - diagnostics
FLOW RATE ml/min
Con
cen
trat
ion
(m
M)
Organic components
Saliva composition
Organic components of saliva Mucins Proline-rich proteins Amylase Lipase Peroxidase Lysozyme Lactoferrin sIgA Histatins Statherin Blood group substances, sugars, steroid hormones,
amino acids, ammonia, urea
Multifunctionality
SalivaryFunctions
Anti-Bacterial
Buffering
Digestion
Mineral-ization
Lubricat-ion &Visco-elasticity
TissueCoating
Anti-Fungal
Anti-Viral
Carbonic anhydrases,Histatins
Amylases,Mucins, Lipase
Cystatins,Histatins, Proline-rich proteins,Statherins
Mucins, Statherins
Amylases,Cystatins, Mucins, Proline-rich proteins, Statherins
Histatins
Cystatins,Mucins
Amylases, Cystatins,Histatins, Mucins,Peroxidases
adapted from M.J. Levine, 1993
Mucins Lubrication Glycoproteins - protein core with many
oligosaccharide side chains attached by O-glycosidic bond
More than 40% of carbohydrates Hydrophillic, entraining water (resists
dehydration) Unique rheological properties (e.g., high
elasticity, adhesiveness, and low solubility) Two major mucins (MG1 and MG2)
Amylases Calcium metalloenzyme Hydrolyzes (1-4) bonds of starches such as amylose
and amylopectin Several salivary isoenzymes Maltose is the major end-product (20% is glucose) Parotis; 30% of total protein in parotid saliva “Appears” to have digestive function - inactivated in
stomach, provides disaccharides for acid-producing bacteria
Why is it also present in tears, serum, bronchial, and male and female urogenital secretions?
A role in modulating bacterial adherence?
Lingual Lipase Secreted by lingual glands and parotis Involved in first phase of fat digestion Hydrolyzes medium- to long-chain
triglycerides Important in digestion of milk fat in
new-born Unlike other mammalian lipases, it is
highly hydrophobic and readily enters fat globules
Statherins Calcium phosphate salts of dental enamel
are soluble under typical conditions of pH and ionic strength
Supersaturation of calcium phosphates maintain enamel integrity
Statherins prevent precipitation or crystallization of supersaturated calcium phosphate in ductal saliva and oral fluid
Produced by acinar cells in salivary glands Also an effective lubricant
Proline-rich Proteins (PRPs)
40% of AAs is proline Inhibitors of calcium phosphate crystal
growth Part of pellicula dentis Subdivided into three groups
Acidic 45%Basic 30%Glycosylated 25%
Lactoferrin Iron-binding protein „Nutritional“ immunity (iron starvation) Some microorganisms (e.g., E. coli) have
adapted to this mechanism by producing enterochelins.bind iron more effectively than lactoferrin iron-rich enterochelins are then reabsorbed by
bacteria Lactoferrin, with or without iron, can be
degraded by some bacterial proteases.
Lysozyme Present in numerous organs and most
body fluids Also called muramidase hydrolysis of (1-4) bond between N-
acetylmuramic acid and N-acetylglucosamine in the peptidoglycan layer of bacteria.Gram negative bacteria generally more
resistant than gram positive because of outer LPS layer
Histatins A group of small histidine-rich proteins Potent inhibitors of Candida albicans
growth
Cystatins Are inhibitors of cysteine-proteases Are ubiquitous in many body fluids Considered to be protective against unwanted
proteolysis bacterial proteases lysed leukocytes
May play inhibit proteases in periodontal tissues
Also have an effect on calcium phosphate precipitation
Salivary peroxidase systems
Sialoperoxidase (SP, salivary peroxidase) Produced in acinar cells of parotid glands Also present in submandibular saliva Readily adsorbed to various surfaces of mouth
enamel, salivary sediment, bacteria, dental plaque
Myeloperoxidase (MP) From leukocytes entering via gingival crevice 15-20% of total peroxidase in whole saliva
24
CIRCAIDIAN RHYTHM OF SALIVA FLOWCIRCAIDIAN RHYTHM OF SALIVA FLOW
No sleep
sleep
12 am 6 am 12 pm 6 pm 12 am 6 am 12 pm 6 pm 12 am
30
20
10
Time of day
25
Effect of feeding on salivary secretion
0
0,005
0,01
0,015
0,02
0,025
0,03
0,035
Volu
me
of s
aliv
a co
llect
ecd
each
10
min
10 min collection periods
Mealduringthis period
Variations in salivary composition
Unstimulated flow Submandibular g. 70% Parotid g. 20% Accesory g. 7% Sublingual 2%
Acid stimulation Submandibular g. 45% Parotid g. 45%
Chewing Submandibular g. 30% Parotid g. 60%
Variations in salivary composition
Parotid secretion increased amylase content
Submandibular secretion increased calcium concentrations
Gingival cervicular fluid
Seminar
Stomatology
Gingival cervicular fluid
Synonyms:Gingival fluidCervicular fluidSulcular fluid
Similar composition as interstitial fluid Flow rate related to degree of gingival
inflamation, circa 0,5-2,4 ml/day
Composition Cells
Desquamated epithelial cells Neutrophils Small amount of lymphocytes and monocytes Bacteria
Inorganic ions Similar to plasma Potassium 2 x higher than in plasma (cell break-up) Calcium higher than in oral fluid
Organic components Similar to plasma - serum albumin, globulins, complement,
protease inhibitors Small organic molecules - lactate, urea, hydroxyproline Enzymes
Function
Protective flow towards oral cavity - washes out potentially harmful cells and molecules
Antibacterial - immunoglobulins Calcium assists pellicle and plaque
fromation but may contribute to calculus formation
Rather response to inflamation