Functional anatomy of mouth Salivary Glands location & structure of salivary glands Additional gland Nerve supply to the salivary glands Composition of saliva Regulation of Salivary secretion Function of saliva Applied aspects of Salivary secretion

1. Salivary gland
Pandian M.
Dept of Physiology
DYPMCKOP

2. SLO
• Functional anatomy of mouth
• Salivary Glands location & structure of salivary glands
• Additional gland
• Nerve supply to the salivary glands
• Composition of saliva
• Regulation of Salivary secretion
• Function of saliva
• Applied aspects of Salivary secretion

3. Introduction
• This is the first juice coming in contact with food
secretion
• These are located outside of the GIT
• Secretion are conveyed to mouth by ducts
• In mammals main salivary glands are :
1. Parotid
2. Submaxillary or submandibular
3. Sublingual

4. FUNCTIONALANATOMY OF MOUTH
• Oral cavity or buccal cavity.
• It is formed by cheeks, lips and palate.
• It encloses the teeth, tongue and salivary glands.
• Mouth opens anteriorly to the exterior through lips and
posteriorly through fauces into the pharynx.
• Digestive juice present in the mouth is saliva, which is
secreted by the salivary glands.

5. Salivary glands:
are composed of 4 major
glands, in addition to
minor glands.
Major:
•2 parotid glands.
•2submandibular
gland
Minor:
•Sublingual.
•Multiple
minor glands

6. Additional gland
1. Lingual
2. Labial
3. Buccal
4. Palatine glands

7. Saliva, secreted by three pairs of salivary glands located in the
head, drains into the mouth through a series of short ducts.
• Which contains mucus, moistens and lubricates the food
particles before swallowing.
• It also contains the enzyme α-amylase (partially digests
polysaccharides).
• A third function of saliva is to dissolve some of the food
molecules
• Finally, saliva has antibacterial properties.
Do you know Any other functions of saliva

8. Location & structure of Salivary glands
1. Parotid glands
• Largest salivary glands is Parotid glands (each weighing 20–
30 g), located near the angles of jaw.
• Secretions are passed on to the Mouth Stensen’s duct
• Opening into the oral cavity opposite to the upper second
molar teeth

9. 2. Submandibular:
• Weight 8 to 10g & present in the submaxillary triangle on the
inner side of the lower jaw
• Wharton’s duct carries the secretions into mouth & opens on
summit of the papilla known as caruncula sublingualis.
• Its located side of frenulum of the tongue

10. 3. Sublingual gland
• It is the smallest of salivary glands
• Weight 2-3 g & it present under the mucous memb on
the floor of the mouth
• Secretions are carried by means 15-20 ducts called
ducts of Rivinus
• Sometimes Ant. Portion of the gland is drained by a
single large duct called Bartholin’s duct.

12. Structure
• Racemose structure which consists of acini & duct system
• Acinus is the secretory unit of the salivary gland & known as
alveolus.
• Acinus consists of secretory epithelial cells this are
pyramidal shaped cells resting on basement memb.
• b/w the epithelial cells & basement memb, spl type of cells
called Basket cells
• This cells are contractile in nature & aid in the expulsion of
saliva to the central lumen.

14. Depending on the secretion & Histological appearances there
are two types of Acini
1. Serous acini – secrete thin watery saliva rich in enzymes
2. Mucous acini – secrete thick viscous saliva rich in
mucin content
Both are present in all the glands but proportion varies
Note.
• The sublingual and the submandibular glands secrete a
fluid that contains a higher concentration of proteins and so
is more viscus as compared to the watery secretion of
parotid glands.

15. SECRETION AND COMPOSITION

16. Mechanism of formation of saliva
• Mechanism of formation of saliva involves two processes:
1. Primary secretion of saliva.
• The acinar cells of salivary glands secrete the initial saliva
into the salivary ducts.
• The initial saliva is isotonic, i.e. has the same Na+, Cl−, K+
and HCO−3 concentrations as plasma.
• However, the initial saliva is soon modified by the salivary
ducts

17. 2. Modification of saliva.
• The ductal cells of tubular portions of the salivary ducts change the
composition of initial saliva.
Reabsorption of Na+ and Cl− occurs in the ductal cells,
• therefore, the concentration of these ions is lower than their plasma
concentration.
Secretion of K+ and HCO3- is caused by the ductal cells,
• therefore, the concentrations of these ions are higher than their plasma
concentrations.
Modified saliva becomes hypotonic in the ducts because the ducts are
relatively impermeable to water.

19. Note.
• Aldosterone acts on the ductal cells to increase the reabsorption of Na+
and Cl− from the salivary ducts (analogous to its actions on renal
tubule).
• Thus a high Na+/Cl− ratio is seen when aldosterone is deficient in
Addison’s disease and in presence of excess aldosterone, the
• Conc. of NaCl− in saliva falls almost to zero and increases K+ conc.

20. PHASES OF SALIVARY SECRETION
1. Cephalic phase
• refers to the secretion of saliva before entering of food into
the mouth.
• It is caused by a conditioned reflex initiated by the mere sight
or smell of food.
2. Buccal phase
• Refers to the secretion of saliva caused by stimulation of
buccal receptors by the presence of food in the mouth.
• It is an unconditioned reflex, partially regulated by the
appetite area of the brain.

21. 3. Oesophageal phase
• Occurs due to the stimulation of salivary glands to a slight degree by
the food passing through oesophagus.
4. Gastric phase refers to the secretion of saliva by the presence of food
in the stomach.
• It specially occurs when irritant food is present in the stomach (e.g.
increased salivation before vomiting).
5. Intestinal phase refers to a salivary secretion caused by the presence
of irritant food in the upper intestine.

22. CONTROL OF SALIVARY SECRETION
• Salivary secretion is controlled entirely by the ANS reflexes.
• Salivary secretion production is increased by both parasympathetic
and sympathetic activity;
• However, the activity of former is more important.

23. I. Parasympathetic control
• Parasympathetic nerve supply Parotid glands are supplied
by the parasympathetic fibres (preganglionic),
• Which arise from the inferior salivary nucleus (dorsal nucleus
of IX nerve) of medulla.
• Pre-ganglionic fibres run via tympanic nerve and small
superficial petrosal nerve to otic ganglion.

24. • Post-ganglionic fibres from the otic ganglion join auriculotemporal
nerve to reach parotid gland
• where fibres are supplied along with blood vessels of gland.

25. • Submandibular and sublingual glands are supplied by the
parasympathetic fibres
• Originating from superior salivary nucleus (dorsal nucleus
of VII nerve).
• Pre-ganglionic fibres run in the nervous intermedius
(sensory division of VII nerve), join the facial nerve and
• leave by its chordatympani branch to join lingual nerve.
• They synapse in the ganglia present near the glands.
• Post-ganglionic fibres arising from the ganglia present near
the glands are supplied to the glands along with the blood
vessels.

27. Parasympathetic reflexes
1. Conditioned reflexes.
2. Unconditioned reflexes

29. 1. Conditioned reflexes.
• Conditioned reflexes are sight, smell or even thought
of palatable food increase the salivary secretion
• This reflex is take over by the impulses coming from
higher centres of brain via parasympathetics
supplying to the salivary glands

30. 2. Unconditioned reflexes
• Its initiated by the stimulation of receptors in the buccal cavity.
• Receptors and afferents, and efferents of unconditioned reflexes are
Receptors:-
Mechanoreceptors
• Excited by tactile stimulation from the tongue, mouth and pharynx.
• The tactile stimuli occur due to the presence of food in the buccal
cavity,
• Chewing movements and irritation of buccal mucosa.

31. • Afferent run in trigeminal nerve branches (such as lingual,
buccal and palatine nerves),
• Pharyngeal branches of vagus and glossopharyngeal nerve

32. • Chemoreceptors, i.e. taste buds are stimulated by the
sensation of taste and chemicals in the food.
Afferents for taste sensation from:
– Posterior 1/3rd of tongue pass via glossopharyngeal
nerve to end in inferior salivary nucleus (dorsal nucleus of IX
nerve), and
– From anterior 2/3rd of tongue pass via nervous
intermedius (branch of VII nerve) to end in superior salivary
nucleus (dorsal nucleus of VII nerve).
• Salivary centre is thus constituted by superior and inferior
salivary nuclei.

35. • Efferent from superior salivary nucleus stimulate the
submandibular and sublingual salivary glands,
• while those from the inferior salivary nucleus stimulate the
parotid glands.
Effects of parasympathetic stimulation
• Parasympathetic nerve stimulation causes salivary gland cells
to secrete a large volume of watery fluid that is high in
electrolytes but low in Ptn’s

36. II. Sympathetic control
Sympathetic nerve supply
• Preganglionic fibers originate from the lateral horn cells of
T1 & T2 segment of SC
• Enter paravertebral sympathetic chain via ventral roots to
synapse with the cells in superior cervical ganglion
• Post ganglionic fibers run along the carotid artery branches
and are supplied to the three pairs of salivary glands along
with blood supply

37. Effects of sympathetic stimulation
• Vasoconstriction in the salivary glands &
• Transient secretion of a very small amt of thick
viscous saliva, rich in mucus & other organic
constitution

38. Paralytic secretion (applied)
• Claude Bernard observed that cutting chordatympani nerve
(parasympathetic ) in dog or cat procedures scanty secretion
of thin turbid saliva
• Which increases to peak on 7th day and diminishes in 3rd
weeks.
• He called it as paralytic secretion bcoz it was caused by
cutting the nerve supply
• Later on it shown that increased secretion is due to an
increased sensitivity of the gland to adrenaline after cutting
the CT nerve

39. EFFECT OF DRUGS AND CHEMICALS
ON SALIVARY SECRETION
Substances which increase salivary secretion
1. Sympathomimetic drugs like adrenaline
and ephedrine.
2. Parasympathomimetic drugs like
acetylcholine, pilocarpine, muscarine and
physostigmine.
3. Histamine.

40. Substances which decrease salivary secretion
1. Sympathetic depressants like ergotamine and
dibenamine.
2. Parasympathetic depressants like atropine and
scopolamine.
3. Anesthetics such as chloroform and ether
stimulate the secretion of saliva.
However, deep anesthesia decreases the secretion
due to central inhibition.

43. PROTECTION
SALIVA - Functions
ALIMENTARY Food approval: taste, texture
Mastication
Swallowing
Digestion
OTHER Vocalization
Excretion ?
Epithelial lubrication
For tooth: Rinsing
Pellicle coat
MATERIALS
Water Mucins
(glycoproteins) Antibodies IgAs
Lysozyme
Amylase

44. FUNCTIONS OF SALIVA
1. Preparation of food for swallowing
2. Appreciation of taste
3. Digestive function

45. 4. Cleansing and protective functions
5. Role in speech
6. Excretory function
7. Regulation of body temperature
8. Regulation of water balance

46. Salivary Gland Diseases
•Functional disorders
•Obstructive disorders
• Infectious disorders
• Neoplastic disorders

47. APPLIED PHYSIOLOGY
HYPOSALIVATION
• Reduction in the secretion of saliva is called
hyposalivation.
• It is of two types, namely temporary hyposalivation
and permanent hyposalivation.
1. Temporary hyposalivation occurs in:
i. Emotional conditions like i. fear, ii. Fever, iii.
Dehydration.

48. 2. Permanent hyposalivation occurs in:
i. Sialolithiasis (obstruction of salivary duct).
ii. Congenital absence or hypoplasia of salivary
glands.
iii. Bell palsy (paralysis of facial nerve).

49. HYPERSALIVATION
• Excess secretion of saliva is known as
hypersalivation.
• In Physiological condition hypersalivation occurs in
pregnancy.
• Hypersalivation in pathological conditions is called
ptyalism, sialorrhea, sialism or sialosis.

50. Hypersalivation occurs in the following pathological
conditions:
1. Decay of tooth or neoplasm (abnormal new
growth or tumor) in mouth or tongue due to continuous
irritation of nerve endings in the mouth.

51. 2. Disease of esophagus, stomach and intestine.
3. Neurological disorders such as cerebral palsy, mental
retardation, cerebral stroke and parkinsonism.
4. Some psychological and psychiatric conditions.
5. Nausea and vomiting.

52. OTHER DISORDERS
In addition to hyposalivation and hypersalivation, salivary
secretion is affected by other disorders also, which include:
1. Xerostomia
2. Drooling
3. Chorda tympani syndrome
4. Paralytic secretion of saliva
5. Augmented secretion of saliva
6. Mumps
7. Sjögren syndrome.

53. Referred :-
• Text book of Medical Physiology
• Guyton, 12th edition,
• Text book of Medical Physiology
• Indu khurana, & Sembulingam
• Fundamental Physiology
• L.P.Reddy
• Principles of Anatomy and Physiology
• Tortora
• Net source

54. THANK YOU . . .