It is the surrounding environment of the teeth, which is one of the most important factors that can protect, process and predict the oral health of an individual. And the main thing that makes that environment is the SALIVA – one of the most important body fluid that is the nature’s miracle in your mouth, the primary defence system for the oral environment. The quality, quantity and composition depending, this miracle fluid helps us in maintaining our health in the following ways: 1. Keeping our mouth in a normal pH (acid-alkaline balance) - neutralizing acid challenges 2. Re-mineralization of teeth -delivering calcium, phosphate and fluoride to the tooth surface 3. Oxygenation and cleaning of oral tissues, flushing food and bacteria 4. Aid in speech and taste 5. Digest and swallow food 6. Anti-bacterial / Anti-viral / Anti-fungal 7. Diagnosis of diseases, hormones, pregnancy, drugs and alcohol testing

1. Presented by:
Aves Khan
BDS 1st
Year
Guided by:
Dr Arushi Kshetrapal
MDS (Oral Pathology)
nature’s miracle……
…… in the mouth

2. Saliva
• Saliva is a mixture of fluids
secreted by the three major
salivary glands, i.e. parotid,
sub-mandibular and sub-
lingual glands, with a slight
contribution from many
minor glands within the oral
cavity.
• The primary defense system
for the oral environment.

3. Saliva – properties & composition
Properties of saliva:
Volume: 1000ml to 1500ml per day
Reaction: Mixed saliva from all the glands is slightly
acidic with pH of 6.35 to 6.85
Tonicity: Hypotonic to plasma

4. Saliva – properties & composition
Composition of saliva:
Saliva
Water – 99.5% Solids – 0.5%
Organic substances Inorganic substances Gases

5. Composition of saliva:
Organic Substances
Enzymes
1.Amylase (ptyaline)
2.Maltase
3.Lingual lipase
4.Lysozyme
5.Phosphatase
6.Carbonic anhydrase
7.Kallikrein
Other organic substances
1.Mucin
2.Albumin
3.Proline-rich protein
4.Lactoferrin
5.IgA
6.Free amino acids etc.

6. Composition of saliva:
Inorganic substances
1.Sodium
2.Calcium
3.Potassium
4.Bicarbonate
5.Chloride
6.Fluoride
7.Phosphate
Gases
1.Oxygen
2.Carbon dioxide
3.Nitrogen

7. Mechanism of Saliva secretion

8. Mechanism of Saliva secretion
• The material secreted
by the acinus is called
the “primary
secretion”.
• The primary secretion
reaches the intercalated
and striated duct where
it modified as follow –

9. 1. Na+
and Cl-
ions of the primary secretion are reabsorbed
2. K+
and HCO3-
ions are secreted by duct cells and are
added to the fluid in the ducts
Mechanism of Saliva secretion

10. Mechanism of Saliva secretion
3. Because ductal epithelium is poorly permeable to
water, the final saliva is usually -
1.Hypotonic
2.Deficient in NaCl but
3.Rich in KHCO3

11. • Only the minor glands secrete saliva
spontaneously.
• Although these glands are innervated and may
increase their secretory rate in response to nervous
activity, they secrete saliva at a low rate, without
exogenous influence during the night.
Spontaneous, Resting & Stimulated secretion

12. • In daytime and at rest, a nervous reflex drive—set
up by low-grade mechanical stimuli due to
movements of the tongue and lips, and mucosal
dryness—acts on the secretory cells, particularly
engaging the submandibular gland
Spontaneous, Resting & Stimulated secretion

13. • In response to strong stimuli, such as citric acid, the
flow rate is about equal to that from the
submandibular gland, whereas in response to
chewing, the flow rate is twice as high as that from
the submandibular gland.
Spontaneous, Resting & Stimulated secretion

14. Salivary Centres

15. Regulation of Salivary Secretion
• The parasympathetic salivary center is located in the
medulla oblongata and is divided into a superior and an
inferior salivary nucleus, and, in addition, an intermediate
zone.

16. • The superior nucleus connects (the facial nerve) with the
submandibular and the sublingual glands, whereas the
inferior nucleus connects (the glossopharyngeal nerve) with
the parotid gland.
• The intermediate zone makes connections with both the
submandibular gland and the parotid gland.
Regulation of Salivary Secretion

18. DIGESTIVE FUNCTIONS:
• Digestive functions include the mechanical handling
of food such as chewing, bolus formation, and
swallowing.
• The chemical degradation of food is by amylase and
lipase—these enzymes continue to exert their
activities in the stomach, amylase exerting its activity
until the acid penetrates the bolus.
Saliva – Functions

19. • The group of digestive functions also includes the
process of dissolving the tastants, and thus allowing
them to interact with the taste buds.
• If pleasant, taste sets up a secretory reflex of gastric
acid as part of the cephalic regulation of gastric
secretion.
Saliva – Functions

20. PROTECTIVE FUNCTIONS:
• Lubrication of the oral structures by mucins,
• the dilution of hot or cold food, and spicy food,
• the ability of the buffer (by bicarbonate, phosphates,
and protein) to maintain salivary pH around 7.0
• the remineralization of enamel by delivering calcium,
phosphate and fluoride to the tooth surface
Saliva – Functions

21. ADDITIONAL FUNCTIONS:
• Additionally, saliva is necessary for articulate speech,
for excretion.
• Moreover, saliva exerts trophic effects. It maintains
the number of taste buds.
• Further, the composition of saliva secreted during
fetal life has importance for the development of oral
structures
Saliva – Functions

22. ADDITIONAL FUNCTIONS:
• Additionally, saliva is necessary for articulate speech
and also for excretion.
• Moreover, saliva exerts trophic effects. It maintains
the number of taste buds.
• Further, the composition of saliva secreted during
fetal life has importance for the development of oral
structures
Saliva – Functions

23. HYPOSILAVATION:
• Hyposalivation is represented by a reduced
salivary flow rate and can be caused by etiologic
factors such as systemic diseases and intake of
various medications or by radiotherapy
following head and neck cancer.
Applied Physiology

24. HYPOSILAVATION:

25. Physiological changes at old age contributing
to hyposalivation

26. HYPERSILAVATION:
• Excess secretion of saliva.
• Physiological condition when hypersalivation occur
is pregnancy
Applied Physiology

27. HYPERSILAVATION:
• Pathological conditions:
1.Decay of tooth
2.Neoplasm (abnormal new growth or tumor) in mouth
or tongue
3.Disease of esophagus, stomach and intestine
4.Neurological disorder such as cerebral palsy, mental
retardation, cerebral stroke and parkinsonism
5.Nausea & vomiting
Applied Physiology

28. Other Disorders:
Xerostomia: Dry mouth due to hyposalivation or
absence of salivary secretion (aptyalism)
Causes:
A.Difficulties in mastication, swallowing and speech
B.Halitosis (bad breath)
Applied Physiology

29. Other Disorders:
Drooling: Excess production of saliva, in assocation
with inability to retain saliva within the mouth
Chorda Tympani Syndrome : The condition
characterized by sweating while eating
Paralytic secretion of saliva: When the
parasympathetic nerve to salivary glands is cut in
experimental animal, salivary secretion increases for
first three weeks (paralytic secretion) and later
diminishes
Applied Physiology

30. Other Disorders:
Augmented secretion of saliva: If the nerves
supplying the salivary glands are simulated twice, the
amount of saliva secreted by the second stimulus is
more than the amount secreted by the first stimulus.
Mumps : The acute viral infection affecting the parotid
glands. It is common in children who are not
immunized.
Applied Physiology

31. Other Disorders:
SjÖgren syndrome: It is an autoimmune disorder in
which the immune cells destroy exocrine glands such
as lacrimal glands and salivary glands.
Applied Physiology

32. Discussion:
1. Volume & medium of saliva
2. Stages of saliva secretion
3. Regulation of salivary secretion
4. Functions of saliva