Salivary Glands

Pure saliva

• Clear, colorless saliva

• Directly collected from the duct openings of specific salivary glands before it mixes with other fluids in the mouth

Desquamated epithelial cells, leukocytes from gingival crevices, lymphocytes from tonsils

The opacity in saliva is due to the presence of _____

Active saliva

Saliva resulting from sight/smell of food or from stimulating material of the oral cavity

Resting saliva

Saliva that occurs in the absence of excitation

Mixed saliva

• Frothy and slightly opalescent fluid containing water, protein, mineral salts, ptyalin, mucin, food particles, desquamated epithelial cells, salivary corpuscles

• Obtained during resting stage; unstimulated

5.6-7.6

pH of saliva

• 99.5% water

• 0.5% organic and inorganic constituents

• Salivary amylase or ptyalin

• Lysozyme

Composition of saliva

Pancreas

Amylase can also be found in what organ?

Amylase or ptyalin

Major salivary protein; present in the parotid gland or submandibular gland

Salivary mucin (mixture of glycoprotein)

What makes saliva viscous?

Lysozyme and albumin

Other proteins in the saliva

• Protection — glycoprotein

• Buffering

• Digestion — amylase

• Taste — gustin

• Antimicrobial action — antibodies; lysozyme

• Maintenance of tooth integrity — calcium & phosphate ion

• Tissue repair

Functions of saliva

• Emotions

• Activity

• Exercise

• Physical and psychological stimulation

What affects saliva secretion?

Exocrine

Classification of saliva according to nature of secretion

Merocrine

Classification of saliva according to behavior of glands

Compound tubuloacinar

Classification of saliva according to morphology

Serous demilunes

Half-moon shape of serous cells found on some mixed salivary glands, particularly submandibular and sublingual glands

Parotid gland

• Largest salivary gland

• Pure serous secretion rich in amylase

• May contain mucous cell (in newborn)

• Striated columnar cells, pyramidal, round basal nuclei

• Apical portion is fitted with secretory/zymogen granules

Trigeminal nerve

Sensory nerve supply of parotid, submandibular, sublingual glands

Superior cervical ganglion

Sympathetic innervation of parotid, submandibular, sublingual glands

Glossopharyngeal nerve, Otic ganglion

Parasympathetic innervation of parotid gland

Submandibular gland

• 2nd largest salivary gland

• Wrapped around mylohyoid

• Mixed seromucous secretion (1/4 mucous, ¾ serous)

• Slightly viscous

• Longer secretory ducts than parotid

Sublingual papilla or caruncula sublingualis

Wharton’s duct enters the oral cavity via the _____

Facial nerve (Chorda tympani), Submandibular ganglion

Parasympathetic innervation of submandibular and sublingual glands

Sublingual glands

• Smallest salivary gland

• Major duct: Bartholin’s duct; Small ducts: Rivinian ducts

• Mixed seromucous (1/3 serous, 2/3 mucous)

  • serous cells are found only in the form of serous demilunes

• Slightly more viscous than submandibular

Type I mucous cells

Produce both neutral and acidic glycoproteins

Type II mucous cells

Produce only acidic glycoproteins

Lamina propria or submucosa of the oral mucosa

Where do minor salivary glands reside in?

Keep the mucosa moist

Function of minor salivary glands

Glands of Nuhn or Glanda of Blandin

• Anterior lingual glands

• mostly mucous

Glands of Von Ebner

• Posterior lingual glands

  • located beneath vallate papillae

• pure serous

• Labial gland

  • Superior

  • Inferior

• Buccal gland

  • Minor buccal

  • Parotid

Glands of the vestibule

• Submandibular gland

• Major sublingual gland

• Minor sublingual gland

• Glossopalatine gland

Glands of the floor of the mouth

• Anterior lingual gland

  • Glands of Nuhn or Glands of Blandin

• Posterior lingual gland

  • Glands of Von Ebner

  • Glands of lingual tonsils

Glands of the tongue

Serous cells

• Secrete mostly protein and small amount of carbs

  • contain ZYMOGEN GRANULES

• Watery secretion

Mucous cells

• High in carbs, low in protein

  • apical portion does not stain strongly bc of high carb content

• Discharge mucin

  • mixes with water oral fluids → becomes mucous

• Pyramidal, flattened nuclei toward base

Mucinogen

Secretory granules of mucous cells

Zymogen granules

Secretory granules that store active amylase

• Fatty degenerative changes

• Fibrosis

• Accumulation of lymphocytes

• Oncocytes — may give rise to neoplasms

Age changes — salivary glands

• Rate of saliva production varies throughout the day

  • low at night → reason for brushing teeth before bed

• Parotitis or mumps: from bacterial/viral infection

• Obstruction to salivary flow: from formation of salivary stones in the ducts

  • stones occur mostly in submandibular glands

Clinical considerations

Myoepithelial cells

Contractile cells of salivary glands

Parotid gland, Von Ebner’s gland

Which salivary glands have pure serous secretion?

Intercalated duct

Excretory duct directly connected to the acini

Striated duct

• Receive secretions from intercalated ducts

• Columnar cells

• Modify the composition of saliva