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The watery secretion colourless,testless produce by pair of salivary
glands.
1: parotid gland (30%)
2: Submandibular gland(35%)
3: Sublingual Glands(35%)
•
The watery content are more in parotid as compared to sub
submandibular and sublingual gland
•
There are several other glands located throughout the oral cavity.
Composition
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Total amount secreted is 500 -1500ml/ day
Ph=6-7.4.(Average 6.8)
Specfic gravity 1007.
Water 99%
Solid 1%
 inorganic(Na+,Cl,k,Hco3
organic L-amylase (ptylin), Lingual lipase,
lysozyme, Killikriem, urea uric acid, cholestrol, Mucin
Mechanism of secretion
 A) primary secretion :This is by the acinar cells of the
s.gland by the process of pressure filtration of plasma .
 This is isotonic of plasma
 Modification of Saliva : The ductal cells line the tubules of
the salivary gland modify the concentration by
1 Reabsorption of Na and Cl
2 secretion of k+ and Hco3
3 the ducts are relatively impermeable to water so the
saliva is formed diluted because more solutes are
observed .
Aldosterone
Aldosterone increases the reabsorption of Na+ and cl so
deficiency of hormones decreases the reabsorption so
its causes increase level of Na+ and Cl in ductal sailva .
 Increase aldosterone will make the concentration of
Na+ and Cl to zero.
Flow of saliva
Increase in the flow of Saliva causes:
 Increase in Na+
 Increase in Cl
 Decrease in k+
 Increase in Hco3
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Decrease in flow of saliva causes
Decrease in Na+
Decrease in cl
Decrease in Hco3
Increase in k
Phases of Salivary secrtion
Cephalic phase
Sight ,smell and thought of food causes increase
in saliva without entry of food in mouth.
This is called as “conditioned reflex.”
This is inborn reflex and its significance is that it
start processes of digestion before the entry of food in
GIT.
Buccal phase
Secretion of saliva occurs when food touches the
receptors in buccal cavity and this process is term as
unconditioned reflex.
Oesophageal/gastric phase
 Food in oesophagus causes release of saliva but the
degree of stimulation is minimum.
 When food enters in stmoch its causes increase in
saliva and the importance is that when ever there is
vomiting there is hyper salivation and its causes
increase pressure in the stomch and tape the contents
out.
Intestinal phase
Entry of food in the intestine will cause increase
production of saliva there is more and more digestive
process and it is helpful in the movement of the food
too.
Control of saliva
By the autonomic nervous system
Parasympathetic
 Salivary enter is in medulla formed by
sup. Salivary N
Inf.salivary N
 Parotid gland is supplied by ISN (dorsal nuclues of 9th CN)
 Preganglionic fibers go through tympanic N and petrosal N to
otic ganglion
 Postganglionic fiber from otic ganglia join auriculotemporal
nerve which ultimately go to parotid gland.
 Submandibular and sublingual are supplied by
superior salivary N (Dorsal N of VII CN)
 Preganglionic fiber run in the nervous intermedius
and join the facial nerve then it leave from chorda
tympani and joins the lingual nerve then it goes to the
ganglion near the glands and supply it as post
ganglionic fibers.
Mechanism Of Action:

Sights, smell, thought of food
↓
Hypothalamus
↓
Salivary Centre
↓
Stimulation of cholinergic Receptors
↓
Ach is produced
↓
Second Messenger IP3 is produced
↓
increase in Calcium
↓
increase in Kallikern
↓
acts on alpha goblin to from bradykinin
↓
local release of VIP (Vasoactive intestinal Peptide)
↓
it causes increase in Na+, K+, and HCO3 in ductal cell and increase in in blood supply of gland
↓
increase production of Silva.
Sympathetic Supply
 Preganglionic Fiber from T1 and T2 enters in the Sympathetic
Chain
↓
Synapsis at superior cervical ganglion
↓
Post Ganglionic Fibers arise and they run along the
carotid artery and supply the glands.
↓
Beta Receptors are present which are stimulated
↓
CAMP
↓
Production of Silva which is thick, viscid and full mucous
Functions of Saliva
 Protected to the buccal Cavity
 Oral hygiene
 Local Immunity
i) Lysozymes which is Bacterocidal
ii) IgA production
iii) Lactoferrin – Bacterostatic
 Dilution of HCL and bile from stomach and intestinal
 Bolus formation and swallowing
 α- Amylase (Ptylin)
acts at pH6.5-7 denatured in Stomach attacks on 1-4
linkage of starch
and convert it into maltose.
 Lingual lipase (initiate digestion of triglyceride
 Taste sensation by dilution
 Facilitation of lips and tongue movements so speech is produced
 Excretion of heavy metal like alcohol morphine – medico legal importance
 Temperature Regulation by panting in lower animals like dog.