Salivary glands_classification_disorders.etc.pptx

• FUNCTIONAL ANATOMY OF MOUTH
• Mouth is otherwise termed as oral cavity or buccal cavity. Its formation takes place by by cheeks,
lips and palate. It encircles the teeth, tongue and salivary glands.
• Mouth opens anteriorly to the exterior through lips and posteriorly through fauces into the pharynx.
• 3)Digestive juice observed in the mouth is saliva, which is secreted with the help of the salivary
glands.

• FUNCTIONS OF MOUTH
• Primary function of mouth is eating and it exhibits a very few other important functions also.
• Functions of mouth include:
• 1. Ingestion of food materials
• 2. Chewing the food and mixing it with saliva
• 3. Appreciation of taste of the food
• 4. Transfer of food (bolus) to the esophagus via swallowing
• 5. Role in speech
• 6. Social functions namely smiling and other expressions.

• SALIVARY GLANDS
• In humans, the secretion of saliva happens by three pairs of major (larger) salivary glands and
some minor (small) salivary glands also.
•
•
• MAJOR SALIVARY GLANDS
• Major glands are:
• 1. Parotid glands
• 2. Submaxillary or submandibular glands
• 3. Sublingual glands.

• 1. Parotid Glands
• a)Parotid gland is the largest salivary gland, located at the side of the face just below and in front
of the ear.
• b) Each gland weighs about 20 to 30 g in adults. Secretions from these glands are emptied into the
oral cavity with the help of Stensen duct.
• c)This duct is about 35 mm to 40 mm long and opens inside the cheek against the upper second
molar tooth

• 2. Submaxillary Glands
• a)Submaxillary glands or submandibular glands are Situated in submaxillary triangle, medial to
mandible.
• b) Each gland weighs about 8 to 10 g. Saliva from these glands is poured into the oral cavity by
Wharton duct, which is about 40 mm long.
• c)The duct opens at the side of frenulum of tongue, , with the help of a small opening on the
summit of papilla termed as caruncula sublingualis.

• 3. Sublingual Glands
• a)Sublingual glands are treated as the smallest salivary glands located in the mucosa at the floor
of the mouth.
• b)Each gland weighs about 2 to 3 g. Saliva from these glands is emptied into 5 to 15 small ducts
termed as ducts of Rivinus.
• c)These ducts open on small papillaeparticul;arly beneath the tongue. One of the ducts is larger
and it is termed as Bartholin duct
• d)It drains the anterior part of the gland and
• opens on caruncula sublingualis near the opening of submaxillary duct

• MINOR SALIVARY GLANDS
• 1. Lingual Mucus Glands
• Lingual mucus glands are located in posterior one third of the tongue, behind circumvallate papillae and at the tip and margins of tongue.
• 2. Lingual Serous Glands
• Lingual serous glands are situated near circumvallate papillae and filiform papillae.
• 3. Buccal Glands
• a)Buccal glands or molar glands are observed between the mucus membrane and buccinator muscle. Four to five of these are larger and located outside
buccinator, around the terminal part of parotid duct.
• 4. Labial Glands
• Labial glands are located beneath the mucus membrane around the orifice of mouth.
•
• Names of ducts of different salkivary glands
• Parotid gland Stensen duct
• Submaxillary gland Wharton duct
• Sublingual gland Ducts of Rivinus/Bartholin duct
•
• 5. Palatal Glands
• Palatal glands are observed beneath the mucus membrane of the soft palate.

• CLASSIFICATION OF SALIVARY GLANDS
• Salivary glands are categorized into three types, dependent upon the type of secretion:
• 1. Serous Glands
• a)Serous glands contain mainly serous cells.
• b)These glands secrete thin and watery saliva. Parotid glands and lingual serous glands are the serous
glands.
• 2. Mucus Glands
• a)Mucus glands consist of primarily f mucus cells.
• b)These glands secrete thick, viscous saliva with high mucin content.
• c) Lingual mucus glands, buccal glands and palatal glands belong to this type.
• 3. Mixed Glands
• a)Mixed glands consist of both serous and mucus cells.
• b)Submandibular, sublingual and labial glands are the mixed glands.
•

• STRUCTURE AND DUCT SYSTEM OF SALIVARY GLANDS
• Salivary glands are formed by acini or alveoli.
• The formation of each acinus takes place with the help of a small group of cells which enclose a
central globular cavity.
• Central cavity of each acinus is continuous with the lumen of the duct.
• The fine duct draining each acinus is termed intercalated duct.
• Many intercalated ducts join together and result in the formation of intralobular duct. 6)Few
intralobular ducts join to gether and lead to the formation of interlobular ducts, which unite to form
the main duct of the gland .
• 7) A gland with this type of structure and duct system is known as racemose type (racemose =
bunch of grapes)

• PROPERTIES AND COMPOSITION OF SALIVA
•
• PROPERTIES OF SALIVA
• 1. Volume: 1000 mL to 1500 mL of saliva is secreted per day and it is approximately about 1 mL/minute.
•
• Contribution by each major salivary gland is:
• i. Parotid glands : 25%
• ii. Submaxillary glands : 70%
• iii. Sublingual glands : 5%.
•
• 2. Reaction: Mixed saliva from all the glands is slightly acidic along with pH of 6.35 to 6.85
• 3. Specific gravity: It ranges between 1.002 and 1.012
• 4. Tonicity: Saliva is hypotonic to plasma.
• COMPOSITION OF SALIVA
• Mixed saliva contains 99.5% water and 0.5% solids.
• .

• FUNCTIONS OF SALIVA
• Saliva is a very essential digestive juice. Since it exhibits many functions, its absence results in
many inconveniences.
• 1. PREPARATION OF FOOD FOR SWALLOWING
• a)When food is taken into the mouth, it is moistened and dissolved with the help of saliva. b)The
mucus membrane of mouth is also moistened by saliva.
• c)It enhances chewin by the movement of tongue, the moistened and masticated food is rolled into
a bolus.
• d)Mucin of saliva lubricates the bolus and enhancing swallowing.

• 2. APPRECIATION OF TASTE
• a)Taste is a chemical sensation.
• B)By its solvent action, saliva dissolves the solid food substances, so that the dissolved substances
can activate the taste buds. The
• c )Activated taste buds recognize the taste.
•
• 3. DIGESTIVE FUNCTION
• Saliva exhibits three digestive enzymes, namely salivary amylase, maltase and lingual lipase .

• Salivary Amylase
• Salivary amylase is a carbohydrate-digesting (amylolytic) enzyme.
• It shows its action on cooked or boiled starch and changes it into dextrin and maltose. c)Though
starch digestion begins in the mouth, major part of it takes place in stomach because, food stays
only for a short time in the mouth.
• d)Optimum pH essential for the activation of salivary amylase is 6. Salivary amylase cannot act
especially on cellulose.
• Maltase
• Maltase is observed only in traces in human saliva and it converts maltose into glucose.
• Lingual Lipase
• Lingual lipase is a lipid-digesting (lipolytic) enzyme.
• Its secretion happens from serous glands located on the posterior aspect of tongue. It digests milk
fats (pre-emulsified fats).
• It hydrolyzes triglycerides into fatty acids and diacylglycerol .

• 4. CLEANSING AND PROTECTIVE FUNCTIONS
• i. Due to the constant secretion of saliva, the mouth and teeth are rinsed and maintained free off
food debris, shed epithelial cells and foreign particles. In this way, saliva inhibits bacterial
• growth by removing materials, which may serve as culture media for the bacterial growth.
• ii. Enzyme lysozyme of saliva destroys some bacteria namely staphylococcus, streptococcus and
brucella.
• iii. Proline-rich proteins present in saliva contains antimicrobial property and neutralize the toxic
substances namely tannins. Tannins are observed in many food substances including fruits.
• iv. Lactoferrin of saliva alsoexhibits antimicrobial property.
• v. Proline-rich proteins and lactoferrin protect the teeth by activating enamel formation.
• vi. Immunoglobulin IgA in saliva also exhibits antibacterial and antiviral actions.
• vii. Mucin present in the saliva provide protection to the mouth
• by lubricating the mucus membrane of mouth.

• ROLE IN SPEECH
• By moistening and lubricating soft parts of mouth and lips, saliva assists regarding speech. 2)If the
mouth becomes dry, articulation and pronunciation becomes difficult.

• EXCRETORY FUNCTION
• Many substances, both organic and inorganic, are Eliminated in saliva.
• It eliminates substances such as mercury, potassium iodide, lead, and thiocyanate.
• Saliva also eliminates some viruses such as those causing rabies and mumps.
• In some pathological conditions, saliva eliminates certain substances, which are not observed in
saliva particularly under normal conditions.
• Example is glucose in diabetes mellitus. In certain conditions, some of the normal constituents of
saliva are eliminated in large quantities.
• For example, excess urea is excreted in saliva particularly during nephritis and excess calcium is
removed especially during hyperparathyroidism.
•

• REGULATION OF BODY TEMPERATURE
• In dogs and cattle, excessive dripping of saliva during panting helps in the loss of heat and
maintenance of body temperature.
• Whatever it may be, in human beings, sweat glands play an important role regarding temperature
regulation and saliva does not exhibit any type of role in this function.

• REGULATION OF WATER BALANCE
• When the body water content reduces, salivary secretion also rediuces.
• This causes dryness of the mouth and induces thirst.
• When water is taken, it quenches the thirst and brings back the body water content

• Digestive enzymes of saliva
• ESalivary amylase All salivary glands
• Acid medium changes starch into maltose
• Maltase
• Major salivary glands Acid medium changes maltose into glucose
• Lingual lipase
• Lingual glands
• Acid medium changes triglycerides of milk fat into fatty
• acids and diacylglycerol

• REGULATION OF SALIVARY SECRETION
• Salivary secretion is controlled with the help of nervous mechanism.
• Autonomic nervous system is participated regarding the regulation of salivary secretion.
• NERVE SUPPLY TO SALIVARY GLANDS
• Salivary glands are supplied by both parasympathetic and sympathetic divisions of autonomic
nervous system.

• PARASYMPATHETIC FIBERS
• Parasympathetic Fibers to Submandibular and Sublingual Glands
• Parasympathetic preganglionic fibers to submandibular and sublingual glands arise particularly from
the superior salivatory nucleus, located in pons.
• After taking origin from this nucleus, the preganglionic fibers run through nervus intermedius of
Wrisberg, geniculate ganglion, the motor fibers of facial nerve, chorda tympani branch of facial
nerve and lingual branch of trigeminal nerve and finally reach the submaxillary ganglion .
• Postganglionic fibers arising from this ganglion Supply particularly the submaxillary and sublingual
glands.
•

• Parasympathetic Fibers to Parotid Gland
• Parasympathetic preganglionic fibers to parotid gland arise from inferior salivatory nucleus located
in the upper part of medulla oblongata.
• From here, the fibers pass through the tympanic branch of glossopharyngeal nerve, tympanic
plexus and lesser petrosal nerve and end in otic ganglion.
• Postganglionic fibers arise from this ganglion and Supply especially the parotid gland by passing
through auriculotemporal branch in mandibular division of trigeminal nerve.

• Function of Parasympathetic Fibers
• Activation of parasympathetic fibers of salivary glands leads to the secretion of saliva along with
large quantity of water.
• It is because the parasympathetic fibers activate the acinar cells and particularly dilate the blood
vessels of salivary glands.
• Whatever it may be, the amount of organic constituents in saliva is less. The neurotransmitter is
acetylcholine.

• SYMPATHETIC FIBERS
• Sympathetic preganglionic fibers to salivary glands arise from the lateral horns of first and second
thoracic segments of spinal cord.
• The fibers leave the cord through the anterior nerve roots and finally end in superior cervical
ganglion of the sympathetic chain.
• 3)Postganglionic fibers arise from this ganglion and are distributed primarily to the salivary glands
along the nerve plexus, around the arteries supplying the glands.
•

• Function of Sympathetic Fibers
• , Stimulation of sympathetic fibers causes secretion of saliva, which is thick and rich in organic
constituents such as mucus.
• It is because, these fibers stimulate the acinar cells and result in vasoconstriction. The
neurotransmitter is noradrenaline.

• REFLEX REGULATION OF SALIVARY SECRETION
• Salivary secretion is controlled by nervous mechanism with the help of reflex action.
• Salivary reflexes are of two types:
•
• 1. Unconditioned reflex.
• 2. Conditioned reflex.

• 1. Unconditioned Reflex
• a)Unconditioned reflex is the inborn reflex that is present since birth.
• b)It does not require any previous experience
• c)This reflex activates salivary secretion If any substance is placed in the mouth.
• d)It is because of the stimulation of nerve endings particularly in the mucus membrane
• of the oral cavity.

• 2. Conditioned Reflex
• a)Conditioned reflex is the one that is produced by experience and it requires previous experience .
• b)Presence of food in the mouth is not necessary to elicit this reflex.
• c)The stimuli for this reflex are the sight, smell, hearing or thought of food.

• EFFECT OF DRUGS AND CHEMICALS ON SALIVARY SECRETION
• Substances which ewnhance salivary secretion
• 1. Sympathomimetic drugs namely adrenaline and ephedrine.
• 2. Parasympathomimetic drugs like acetylcholine, pilocarpine, muscarine and physostigmine.
• 3. Histamine.
• Substances which reduce salivary secretion
• 1. Sympathetic depressants like ergotamine and dibenamine.
• 2. Parasympathetic depressants like atropine and
• scopolamine.
• 3. Anesthetics such as chloroform and ether activate
• the secretion of saliva. Whatever it may be, deep anesthesia
• Reduces the secretion because of central inhibition.

• 
APPLIED PHYSIOLOGY
• HYPOSALIVATION
• Reduction in the secretion of saliva is termed as
• hyposalivation. It is of two types, namely temporary
• hyposalivation and permanent hyposalivation. 1. Temporary hyposalivation takes place in:
• i. Emotional conditions like fear.
• ii. Fever.
• iii. Dehydration.
• 2. Permanent hyposalivation happens in:
• i. Sialolithiasis (obstruction of salivary duct).
• ii. Congenital absence or hypoplasia of salivary
• glands.
• iii. Bell palsy (paralysis of facial nerve).

• HYPERSALIVATION
• Excess secretion of saliva is termed as hypersalivation. Physiological condition if hypersalivation
happens is pregnancy. Hypersalivation in pathological conditions is
• termed as ptyalism, sialorrhea, sialism or sialosis. Hypersalivation happens 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.
• 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

• OTHER DISORDERS
• Besides, hyposalivation and hypersalivation, salivary secretion is influenced 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.

• 1. Xerostomia
• Xerostomia means dry mouth. It is also known as pasties or cottonmouth. It is because of hyposalivation
or absence of salivary secretion (aptyalism).
• Causes
• i. Dehydration or renal failure.
• ii. Sjögren syndrome.
• iii. Radiotherapy.
• iv. Trauma to salivary gland or their ducts.
• v. Side effect of some drugs namely antihistamines, antidepressants, monoamine oxidase inhibitors,
antiparkinsonian drugs and antimuscarinic drugs.
• vi. Shock.
• vii. After smoking marijuana (psychoactive compound from the plant Cannabis).
• Xerostomia leads to difficulties in mastication, swallow ing and speech. It also results in halitosis (bad
breath; exhalation of unpleasant odors).

• 2. Drooling
• Uncontrolled flow of saliva outside the mouth is known as drooling. It is often termed as ptyalism.
•
• Causes
• Drooling happens due to excess production of saliva, in association with inability to retain saliva
within the mouth.
• Drooling happens in the following conditions:
• i. During teeth eruption in children.
• ii. Upper respiratory tract infection or nasal allergies
• in children.
• iii. Difficulty in swallowing.
• iv. Tonsillitis.
• v. Peritonsillar abscess.

• 3. Chorda Tympani Syndrome
• a)Chorda tympani syndrome is the condition manifested by sweating while eating.
• b) During trauma or surgical procedure, some of the parasympathetic nerve fibers to salivary glands
may be severed.
• c)During the regeneration, some of these nerve fibers, which run alongwith chorda tympani branch
of facial nerve may deviate and join along with the nerve fibers supplying sweat glands.
• d) If the food is placed in the mouth, salivary secretionis linked to sweat secretion.

• 4. Paralytic Secretion of Saliva
• a)When the parasympathetic nerve to salivary gland is cut in experimental animals, salivary
secretion enhances for first three weeks and later diminishes; finally it stops at about sixth week.
• b) The enhanced secretion of saliva after cutting the parasympathetic nerve fibers is known as
paralytic secretion.
• c) It is due to hyperactivity of sympathetic nerve fibers to salivary glands after cutting the
parasympathetic fibers.
• d)These hyperactive sympathetic fibers release especially large amount of catecholamines, which
induce paralytic secretion.
• e)Afterwards, the acinar cells of the salivary glands become hypersensitive to catecholamines after
denervation.
• f)The paralytic secretion does not happen after the sympathetic nerve fibers to salivary glands are
cut.
•

• 5. Augmented Secretion of Saliva
• a)If the nerves supplying salivary glands are activated twice, the amount of saliva secreted by the
second stimulus is more than the amount secreted by the first stimulus.
• b) It is because, the first stimulus enhances excitability of acinar cells, so that if the second
stimulus is applied, the salivary secretion is augmented.
•

• 6. Mumps
• a)Mumps is the acute viral infection influencing the parotid glands.
• b)The virus causing this disease is paramyxovirus.
• c)It is common in children who are not exposed to immunization.
• d)It takes place in adults also. Features of mumps are puffiness of cheeks (due to swelling of
parotid glands), fever, sore throat and weakness. Mumps impacts meninges, gonads
• and pancreas also.

• 7. Sjögren Syndrome
• a)Sjögren syndrome is an autoimmune disorder in which the immune cells kill exocrine glands
namely lacrimal glands and salivary glands.
• b) It is named after Henrik Sjögren who discovered it.
• c) Common symptoms of this syndrome include dryness of the mouth because of lack of saliva
(xerostomia), persistent cough and dryness of eyes.
• d) In some cases, it leads to dryness of skin, nose and vagina. In severe conditions, the
organs like kidneys, lungs, liver, pancreas, thyroid, blood vessels and brain are affected.

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• 4.
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