Detail about Saliva

2. Saliva is produced in and secreted from acinar cells in
salivary glands. Major glands of secretions are parotid
submandibular, and sublingual.
Daily secretion - 800-1500 mL
 pH - 6-7

3. Functions of Saliva
 Moistening food
 Beginning of digestion
 Adjust salt appetite
 Containing factors that inhibit adhesion and destroy bacteria.

4. a
f
Outline of multifunctions of salivary secreations
Salivary
Secretions
i
k
(4) Buffering
(6) Mineral-
ization
(7) Lubricat-
ion &Visco-
elasticity
(8) Tissue
Coating
(1) Anti-
Fungal
(2) Anti-
Viral
Carbonic anhydrases,
Histatins
Cystatins,
Histatins, Proline-
rich proteins,
Statherins
Mucins, Statherins
Amylases,
Cystatins, Mucins,
Proline-rich proteins, Statherins
Histatins
Cystatins,
Mucins
Amylases, Cystatins,
Histatins, Mucins,
Peroxidases

5. Composition of Saliva
1-Aqueous fluids
 H2O, α-amylase, lingual lipase, IgA, kallikrein, muramidase (lyses muramic
acid of Staphylococcus) & lactoferrin.
2 - Electrolytes or inorganics
 Ca, Ph, F, K, Na & Cl
 HCO3 defense enemal against acids (pH5.6) produced by
cariogenic bacteria.
 During hypotonic Saliva (low flow rate):
o High and HCO3 (Pushes pH of stimulated saliva up to 8)
o Low Na andCI−

6. 3-Mucus secretion proteins
Mucin
Statherins
Proline-rich Proteins
Anti-microbial proteins
6)Lactoferrin
7)Histatins
8)Lysozyme
9)Cystatins
10)Salivary peroxidase
11)Secretory Immunoglobulins

7. Enzymes
It cleaves α -1 ,4-glycosidic bonds of starches such as
amylose and amylopectin
Maltose is the major end-product (20% is glucose)
Optimum pH is 7 and inactivated at pH 4 but continues
to work for sometime in unmixed food in oral portion of
stomach
2) Lingual lipase (hydrophobic)
It is secreted by von Ebner’s glands of tongue and
hydrolyzes lipids
It continues working into duodenum
1) α-amylase, parotid glands

8. Mucus secretion proteins
(1) Mucins
 Asymmetrical molecules of globular proteins with polypeptide
backbone (apomucin) and side-chain of negatively charged
groups (e.g. sialic acid and bound sulfate).
 Hydrophillic (resists dehydration, high elasticity, adhesiveness,
and low solubility)
 Two major mucins (MG1 and MG2)

9. Mucin Functions
 Lubrication &Visco-elasticity
 Tissue coating (protection)
 Aggregation of bacterial cells
– Bacterial adhere to mucins may result in surface attachment, or
– Mucin-coated bacteria may be unable to attach to surface
 Bacterial adhesion
– Mucin oligosaccharides mimic those on mucosal cell surface
– React with bacterial adhesins, thereby blocking them

10. (2) Statherins
 Statherins prevent precipitation or crystallization of
supersaturated calcium phosphate in ductal saliva and oral fluid
 Lubrication and viscosity
 40% of amino acids is proline, Subdivided into three groups
(acidic, basic, glycosylated)
 Inhibitors of calcium phosphate crystal growth
(3) Proline-rich Proteins

11. (5) Anti-microbial proteins
1- Lactoferrin
Iron-binding protein
Some microorganisms (e.g., E. coli) have adapted to this mechanism by
producing enterochelins.
2-Histatins
A group of small histidine-rich proteins
Protent inhibitors of Candida albicans growth

12. 3- Lysozyme (muramidase )
 Present in numerous organs and most body fluids
 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 lipid phosphate layer.

13. 4- Cystatins
 Are inhibitors of cysteine-proteases
 Considered to be protective against unwanted proteolysis
– bacterial proteases
– lysed leukocytes
 They inhibit proteases in periodontal tissues
 They affect on calcium phosphate precipitation

14. 5- Salivary peroxidases
 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

15. 6- Secretory Immunoglobulins
Immunoglobulin A (IgA) is an antibody secreted by mucosal linings in
mucous secretions.
IgA has two subclasses (IgA1 and IgA2) and can exist in a dimeric form
called secretory IgA (sIgA).
The secretory component of sIgA protects the immunoglobulin from the
being degraded by proteolytic enzymes
It plays a critical role in mucosal immunity.