1. SALIVA.
Dr. VISHNUDAS PRABHU

2. CONTENTS INTRODUCTION SALIVARY FLOW RATE COMPOSITION FUNCTIONS
CONTROL OF SECRETION
COMPOSITION OF ARTIFICIAL SALIVA

3. INTRODUCTION
Saliva is a complex fluid, produced by the salivary glands whose important role is maintaining the well-being of the mouth.
Saliva produced by major salivary gland differ from one another in composition
Parotid gland secretes a watery saliva rich in enzymes like amylase, proline rich proteins and glycoproteins.

4. Salivary glands
Major
Minor
Parotid
- lingual mucous glands
Sublingual
- labial glands
-palatal glands
-buccal glands
-lingual serous glands
Submandibular

5. Submandibular gland contains high proportion of glycosylated substances such as mucin.
Sublingual gland produces a viscous saliva rich in mucin.
Secretion of all the major and minor salivary glands contribute whole saliva.

6. It also contains desquamated oral epithelial cells, microorganisms and their products, leukocytes, fluid from gingival crevice, and food remanants.
Total volume of saliva secreted by humans is approximately ml/day.
Submandibular-60%,parotid-30%,sublingual-5% and 1%-minor salivary glands.
The pH of saliva ranges from but for parotid gland ranges from

7. Ducts of major salivary glands-
parotid-stensen’s duct
submandibular-wharton’s duct
sublingual-bartholin’s duct

9. Structure of Salivary gland

10. THE SECRETORY UNIT The basic building block of all salivary glands
Saliva formed in acini flows down DUCTS to empty into the oral cavity.
ACINI - water and ions derived from plasma

11. Salivary flow rate: Exhibit diurnal and seasonal variations
Peak : mid afternoon
spring
Normal salivary flow rate:
O.1 to 0.4 ml/min(unstimulated)
ml/min (stimulated)
During sleep flow is negligible.

12. Approximately 0.5litres of saliva is secreted per day,of which 25%comes from submandibular salivary glands and 66%from parotids.
During sleep flow rate is negligible.

14. Composition saliva Solids-0.5% Water- 99.5% Organic substances Enzymes
Amylase(ptyalin)
Maltase
Lingual lipase
Lysozyme
Phosphatase
Carbonic anhydrase
kallikrein
Other organic substances
Albumin
Mucin
Proline rich proteins
Lactoferrin
IgA
Blood group antigens
Free amino acids
Nonprotein nitrogenous substances-
Urea,uric acid creatinine,xanthine
Inorganic substances
gases
sodium
Calcium
potassium
Bicarbonates
Bromide
Chloride
Fluoride
Phosphate
Oxygen
Carbon dioxide
nitrogen

15. FUNCTIONS
Important function of the salivary gland is production and secretion of saliva.
PROTECTION:
Constant secretion of saliva prevents desication of oral tissues.
Absence of which leads to degeneration and atrophy.
Fluid like nature provides a washing action to flush away debris and the non adherent bacteria.

16. Saliva protects the mucosa from chemical and thermal insults.
LUBRICATION:
Saliva has high molecular weight glycoproteins responsible for oral, oropharengeal and oesophageal mucosal lubrication.
BUFFRERING:
Buffering system of saliva is mainly from bicarbonate and to some extent phosphate ion.

17. Metabolism of salivary proteins and peptides provide urea and ammonia to increase the pH.
This high pH is nonconductive for cariogenic bacteria to survive, ferment carbohydrate and produce acid to cause tooth decay.

18. FORMATION OF ENAMEL PELLICLE
Salivary protein called proline rich protein and statherin, a small tyrosine rich protein inhibit precipitation of calcium phosphate.
Along with salivary glycoprotein, statherin and certain of the proline rich protein bind to tooth surface forming acquired enamel pellicle.
Resulting super saturation of calcium and phosphate reduces dissolution and promotes remineralization.

19. On the surface of the tooth a high concentration of calcium and phosphate cause posteuruptive maturation of the enamel.
Increases surface hardness and resistant to demineralization.
Remineralization is enhanced by flouride ions in saliva.

20. ANTIBACTERIAL :
The acinar cells secrete peroxidase and ductal cells secretes thiocyanate which establishes bactericidal system of saliva.
Peroxidase in presence of hydrogenperoxidase and thiocyanate catalyses the formation of hypothiocyanate which is inhibitory to bacteria.
Lysozyme hydrolyzes the bacterial cellwall resulting in cell lysis.

21. ANTIOXIDANT :
Antioxidant defense mechanism is exerted by uric acid and ascorbic acid .
Profound amount is secreted by the parotid during meal times.
This helps in reducing oxidant stress and maintain oral integrity.

22. Another antibacterial substance present in saliva is lactoferrin an iron binding protein.
In the presence of specific antibody, lactoferrin which is not saturated with iron enhances the inhibitary effect of the antibody on microorganisms.
DIGESTION:
Digestive function is mainly due to presence of salivary amylase, lingual lipase enzymes.

23. Salivary amylase acts on ingested carbohydrate to produce glucose and maltose.
Lingual lipase produced by the lingual serous glands initiates the digestion of dietary lipids hydrolyzing triglycerides to monoglycerides and diglycerides.
MASTICATION AND DEGLUTITION:
Saliva moistens the food and helps its breakdown into smaller particles to initiate digestion.
Helps in the formation of bolus and facilitate deglutition.

24. TASTE SENSATION:
Saliva will emulsify the food taken which is a prerequisite for the sense or percepion of taste.
SPEECH:
Saliva keeps the oral tissue moist and well lubricated facilitating speech.
EXCRETION:
Many substances from blood reach the saliva, thus can be considered as a route of excretion.

25. Multifunctionality Amylases, Cystatins, Carbonic anhydrases,
Histatins, Mucins,
Peroxidases
Carbonic anhydrases,
Histatins
Anti-
Bacterial
Buffering
Amylases,
Mucins, Lipase
Cystatins,
Mucins
Anti-
Viral
Digestion
Salivary
Families
Mineral-
ization
Anti-
Fungal
Cystatins,
Histatins, Proline-
rich proteins,
Statherins
Histatins
Lubricat-
ion &Visco-
elasticity
Tissue
Coating
Amylases,
Cystatins, Mucins,
Proline-rich proteins, Statherins
Mucins, Statherins
adapted from M.J. Levine, 1993

26. FORMATION AND SECRETION
It has two stages of formation.
First stage - cells of secretory end piece & intercalated duct produce primary saliva. It is isotonic fluid, containing most of the organic components & H2O secreted by gland.

27. Second stage - primary saliva modified as it passes through the striated & excretory ducts by reabsorption & secretion of electrolyte. Final saliva is hypotonic.
Protein secretion occur by exocytosis , ie fusion of secretory granules with the luminal membrane to release their content into lumen.

28. Hypotonic final saliva into mouth
TWO STAGE HYPOTHESIS OF SALIVA FORMATION
Most proteins
Na+ Cl- resorbed
Hypotonic final saliva into mouth
Water & electrolytes
Some proteins electrolytes
K+ secreted
Isotonic
primary saliva

29. REGULATION OF SALIVARY SECRETION
It is regulated only by nervous mechanism. Autonomic nervous system is involved in the regulatory function.

30. Nerve supply to salivary glands
Parasympathetic fibers to submandibular and sublingual glands
superior salivatory nucleus situated in pons
Submaxillary ganglion
submandibular and sub lingual glands

31. Parasympathetic fibers to parotid gland
inferior salivatory nucleus
End in the otic ganglion
Parotid gland

32. FUNCTION-
On stimulation of parasympathetic fibers, profuse and watery saliva is secreted. These fibers activate the acinar cells and dilate the blood vessels of salivary glands through neurotransmitter acetylcholine.

34. Superior cervical ganglion
SYMPATHETIC FIBERS
Lateral horns of first and second thoracic segments of spinal cord.
Superior cervical ganglion
Salivary glands

35. FUNCTION-
The stimulation of sympathetic fibers causes less secretion of saliva,which is thick and rich in mucus.it is because these fibers activate acinar cells and cause vasoconstriction by secreting nor adrenaline.

36. Conditions that affect salivation
Physiologic
Taste
Surface texture
Dehydration
Age
Mastication
Emotion

37. Pathologic conditions that increase salivation
Digestive tract irritants
Ill fitting dentures/inadequate interocclusal distance
Vitamin deficiency
Trauma from surgery

38. Pathologic conditions that decrease salivation
Senile atrophy of the salivary glands
Irradiation therapy
Dieseases of the brain stem
Diabetes mellitus/ insipidus
Diarrhoea
Acute infectious diseases

39. Drugs that increase salivation
Cholinesterase inhibitors. Ex.prostigmine
Adrenergic stimulating drugs. Ex.epinephrine
Sialogogues. Ex.pilocarpine.

40. Drugs that decrease salivation
Antihistamines Antianxiety agents
Antidepressant Anti arrhythmic agents
Drugs for peptic ulcer Antipsychotics
Antiparkinsonian drugs
Antisialogogues
Diuretics
Decongestants
Antihypertensives

41. Xerostomia Dry mouth Due to hyposalivation or aptyalism
Causes of this disease are:
-dehydration or renal failure
-sjogren’s syndrome
-radiotherapy
-trauma to salivary gland
-side effect of drugs like antihistamines, antidepressants and antiparkinsonian drugs
-shock

42. Drooling -It occurs in following conditions:
Uncontrolled flow of saliva (ptyalism)
Teeth eruption
Upper respiratory tract infection
Tonsillitis
Peritonsillar abscess

43. Chorda tympani syndrome
Condition characterised by sweating while eating
Some paraympathetic fibers get severed during surgical procedure and during regeneration some nerve fibers that run along with chorda tympani branch of facial nerve may deviate and join fibers supplying sweat glands.

44. Sjogren’s syndrome
Autoimmune disorder in which the immune cells destroy exocrine glands such as lacrimal and salivary glands
Common symptoms are -dryness of mouth
-persistent cough
-dryness of eyes

45. REFERENCES Orban’s Oral Histology & Embryology-12th Edi
Tencate’s Oral Histology-7th Edi
Salivary Diagnostics- David T Wong
Histology For Pathologist- S S Sternberg-2nd Edi