THE SALIVARY GLANDS

WHAT IS THIS?

Saliva

complex fluid found lubricating the mucosa and teeth of the oral cavity

secreted by the salivary glands Major Minor

Types of Saliva

salivary glands, their cells and ducts are greatly responsible for the modification and kind of saliva being secreted

It is of three types: Serous Saliva Viscous Saliva Mixed Saliva

Serous Saliva

Content: Amylase protein polysaccharides

Cell: Serous Cells “watery saliva” Glands that secrete this type:

Parotid Gland Von Ebner’s glands

Viscous Saliva

Content: Mucins (glycoproteins) Carbohydrates

Cell: Mucous Cells Thick and viscous Glands that secrete this type:

Sublingual Gland Minor Salivary Glands (except Von Ebner’s

glands)

Mixed Saliva

simply the combination of the aforementioned types of saliva

Able to do a multitude of significant functions

Secreted by: Submandibular Gland Sublingual Gland

Cells: Serous Cells Mucous Cells

Functions of Saliva

Main function: maintaining the well-being of the mouth

Other important functions: Protection Buffering Action Digestion Facilitation of Taste Defensive Action against Microbes Ionic Exchange between Tooth Surface

Functions of SalivaEffect Active

Constituent

Protection Lubrication, lavage, pellicle formation

GlycoproteinWater

Buffering Action Regulates pH Phosphate and Bicarbonate

Digestion Digests starchDigests lipidsBolus formation

AmylaseLingual Lipase

Facilitation of Taste Taste bud growth and maturation, dissolves substances to carry to taste buds

Gustin

Defensive Action Against Microbes

AntibodiesHostile Environment

LysozymeLactoferrinIgA

Ionic Exchange Between Tooth Surface

Posteruptive Maturation of EnamelRepair

CalciumPhosphate

MAJOR SALIVARY GLANDS

Major Salivary Glands

Functional Unit Parenchyma Stroma

In some books: salivon Three pairs:

Parotid glands Submandibular glands Sublingual glands

Parotid Glands

In front of the ear behind the ramus of mandible

Purely serous Ptyalin and IgA Stensen’s duct-

opens opposite the upper second molar

Parotid Glands

Nerve supply: CN V Sympathetic control:

superior cervical ganglion

Parasympathetic control: CN IX, oticganglion

Submandibular Glands

Inner aspect of the mandible below the floor of the oral cavity

Mixed, 90% serous 10% mucous Secretes lysozymes Wharton’s duct: opens at each side of

the sublingual folds

Submandibular Glands

Serous demilunes

1: intralobular ducts/ striated ducts2: mucous acinus3: serous demilunes

Submandibular Glands

Nerve supply: CN V Sympathetic

control: superior cervical ganglion

Parasympathetic control: CN VII, chorda tympani, submandibular ganglion

Sublingual Glands

Floor of the mouth, below the tongue

Mixed, more mucous Ducts of Rivinus Bartholin’s duct:

opens into Wharton’sduct

Sublingual Glands

Nerve supply: CN V Sympathetic control: superior cervical

ganglion Parasympathetic control: CN VII, chorda

tympani, submandibular ganglion

MINOR SALIVARY GLANDS

MINOR SALIVARY GLANDS

Over 600 present in the oral cavity Types

Mucous producing minor salivary glands Serous fluid producing minor salivary

glands

Mucous Producing Minor Salivary Glands Submucosa of the oral mucosa 1-2 mm in diameter Not encapsulated Number of acini connected in a tiny

lobule

Serous Fluid Producing Minor Salivary Glands Aka. Von Ebner’s Glands Lipid hydrolysis and perception of taste Located around the foliate and

circumvallate papillae

Labial Glands

Inner surface of lips Mixed saliva Cells have distinct

mucoalbuminouscharacter

Terminal portions often form typicaldemilunes

Minor Buccal Glands

Continuation of the labial glands in the cheek

Lie within the vicinity of the opening of the parotid duct

Drain into the third molar region Therefore, it is known as molar glands

Glossopalatine Glands

Pure mucous glands Continuation of the lesser sublingual

glands (posteriorly) Ascend in the mucosa of the

glossopalatine fold

Palatine Glands

Pure mucous glands Occupy the roof of the oral cavity Divided into the glands of the:

Hard palate Soft palate and uvula

Glands of the Tongue

Anterior lingual gland Anterior part- chiefly mucous Posterior part- branching tubules lined with

mucous cells and capped with demilunes of serous cells

Posterior lingual glands Base of the tongue- purely mucous Glands of the vallate papillae (Von Ebner’s

glands)- purely serous, opens into the trough (depression) of the vallate papillae

Glands of the Tongue

Von Ebner’s Glands

STRUCTURES OF SALIVARY GLANDS

STRUCTURES OF SALIVARY GLANDS Parenchyma of glands consists of:

Secretory Portions Branching Duct Sytem

Lobules Septae Capsule

SECRETORY PORTIONS

Serous Cells

Seromucous cells Resemble

truncated pyramids

Tight junctions Junctional

complexes Collectively,

serous acini

Apical Cytoplasm of Serous Cells containing secretory granules

Mucous Cells

Adapted for production, storage, and secretion of proteinaceous material

Mucins Collectively,

mucous acini

Mucous Cells in tubulard secretory end pieces.

Mucous cells showing the serous demilunes.

Myoepithelial Cells

Flattened stellate cells

Desmosomes

Myoepithelial Cells

DUCTAL SYSTEM

Intercalated Ducts

Classified as intralobular duct

Smallest branch of the system of ducts

Prominent in Salivary Glands

Frequent in Parotid Gland

Striated Ducts

Formed by union of Intercalated Ducts

Terminal Excretory Ducts

Special eosinophilic cells

Terminal Excretory Ducts

Interlobular excretory duct

ADDITIONAL INFORMATION

SOURCE: MASTER DENTISTRY VOL. III: ORAL BIOLOGY

SALIVATION REFLEX ACTIVITY

Reflex Activity

Resting flow: keeps the mouth and oropharynx moist

Food and the prospect of eating: most saliva-inducing stimuli

Whole-mouth saliva contribution when stimulated: Parotid gland: 50% Submandibular gland: 30% Sublingual and minor salivary glands: 20%

Reflexes

Gustatory-salivary reflex Sour>umami>salty>sweet>bitter

Masticatory-salivary reflex Saliva flow is directly proportional to

masticatory forces Olfactory-salivary reflex

No reflex response from the parotid gland Increase in salivary secretion from the

submandibular and sublingual glands

Reflexes

Visual and psychic salivary reflex Stimuli: thought and sight of food

Oral nociceptor-salivary reflex Stimulation of the trigeminal afferent

nociceptive fibers Increase in parotid saliva secretion

Esophageal-salivary reflex Waterbrash phenomenon: sudden filling of

the mouth with fluids

DEVELOPMENT OF SALIVARY GLANDS

Development of Salivary Glands Derived from the oral mucosa Arise in weeks 5-6 of embryonic life

Development of Salivary GlandsPRIMORDIA TIME OF

DEVELOPMENT

EMBRYONIC ORIGIN

REGION

Parotid gland primordia (anlage)

5th to 6th week

Ectoderm Labiogingival sulcus

Submandibular gland primordia

6th week Endoderm Hyoid arch

Sublingual gland primordia

7th to 8th week

Endoderm Linguogingival sulcus

Intraoral minor salivary glands

3rd month

Development of Salivary Glands

BudsEpithelial cords

Terminal bulbs

Form clefts

Branches

Repeat process

AGE CHANGES

Age Changes

the aging salivary glands are known to undergo structural changes

The lobule structure becomes less ordered The acini vary more in size and eventually

atrophy Interlobular ducts become more prominent and

the percentage of fibroadipose tissue increases

Age Changes

Changes in the salivary glands (submandibular,parotid (less) and minor salivary glands) Shrinkage of cells Dilation of ducts Oncocytic transformation Increased adiposity Fibrosis Focal microcalcifications with obstruction Chronic inflammation

CLINICAL CONSIDERATIONS

Mucoceles

CAUSE: trauma to excretory ducts of the minor glands which allows the spillage of mucus into the surrounding connective tissue

PHYSIOLOGIC MANIFESTATION: formation of painless, smooth surfaced, bluish lesions

TREATMENT:

self-limiting (acute) or

surgery (chronic)

Mucocele

Ranulas Type of mucocele CAUSE: blocked sublingual gland ducts PHYSIOLOGIC MANIFESTATION: Unilateral,

soft-tissue lesions, often with a bluish appearance. Vary in size and may cross the midline of the

mouth and cause deviation of the tongue TREATMENT:

self-limiting (acute)

surgery (chronic)

Ranula

Sialolithiasis

CAUSE: inactivity of the glands Metabolic conditions that promote salt precipitation in

the glands Predisposing factors: dehydration and poor oral

hygiene PHYSIOLOGIC MANIFESTATION: formation of

caliculi TREATMENT: massaged out by a specialist,

surgery, antibiotics

Sialolithiasis

Necrotizing Sialometaplasia

UNKNOWN CAUSE Possible etiologic agent: smoking, trauma, vascular

disease PHYSIOLOGIC MANIFESTATION: uncommon

benign lesion and inflammatory condition that affects salivary glands, usually the minor salivary glands

TREATMENT:

resolves spontaneously,

self-limiting

Necrotizing Sialometaplasia

Mumps

Aka. epidemic parotitis (viral) Occurs usually during childhood CAUSE: paramyxovirus that infects the parotid

glands PHYSIOLOGIC MANIFESTATION: inflammation

of the parotid glands located on either side of the face

TREATMENT: warm compress,

warm, salt water rinses, antibiotics,

surgery, anti-inflammatory

medications

Mumps

Salivary Gland Neoplasm

Aka. Salivary gland cancer CAUSE: rapid cell growth of the salivary gland PHYSIOLOGIC MANIFESTATION: present as

painless, slow-growing masses TREATMENT: radiation therapy, chemotherapy

Salivary Gland Neoplasms

Irradiation Reaction (Xerostomia) subjective complaint of dry mouth due to a lack

of saliva CAUSE: tumoricidal doses of ionizing radiation,

excessive clearance or breathing through the mouth, hyposalivation (decreased saliva production)

PHYSIOLOGIC MANIFESTATION: dry oral mucosa

TREATMENT: frequent sips of water and frequent mouth care

Xerostomia

THE END

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