OH SALIVA

What is saliva?

A major secretion in the oral cavity that keeps the oral cavity moist.

What are the main glands producing saliva?

• Submandibular glands (60%)

• Parotid glands (30%)

• Sublingual glands (5% or less)

• Minor salivary glands (7%)

What is the total volume of saliva secreted daily by humans?

750 mL

What is the composition of saliva?

• 99% → water

• 1% or less → inorganic ions

  • Na, K, Cl, HCO3)

  • secretory proteins

  • glycoproteins

What are the components of saliva?

• Desquamated epithelial cells

• Leukocytes

• Microorganisms and their products

• Fluid from gingival sulcus

• Food remnants

What is the most important function of saliva?

Protection

• washing, flushing, lubrication, and barrier against toxins and trauma

What is the buffering action of saliva?

• Bicarbonate and phosphate protect teeth from demineralization

• Metabolism of proteins by bacteria helps increase pH towards alkalinity

What is pellicle formation?

Salivary proteins bind to tooth surfaces to form a pellicle that helps protect the tooth surface and aids the initial attachment of bacteria.

How does saliva help maintain tooth integrity?

• High calcium and phosphate concentrations increase enamel hardness, making it resistant to demineralization

• Fluoride ions help with remineralization

What antimicrobial actions does saliva have?

It contains: proteins and peptides with antimicrobial, antifungal, and antiviral activity. It also has secretory IgA to agglutinate microorganisms.

How does saliva contribute to digestion?

It begins digestion by solubilizing food substances and by the action of amylase (carbohydrates) and lipase (lipids).

How does saliva aid in tissue repair?

Saliva promotes tissue growth, differentiation, and wound healing through growth factors and biologically active peptides.

How does saliva play a role in taste?

It solubilizes food substances, which are sensed by taste buds, and contains proteins that have a trophic effect on taste receptors.

What are the three major salivary glands?

1. Parotid Glands

2. Submandibular Glands

3. Sublingual Glands

Where is the Parotid Gland located?

• Superficial portion in front of the external ear

  • deeper portion behind the ramus of the mandible

What type of cells are found in the Parotid Gland?

Serous cells

What is the secretion percentage of the Parotid Glands?

25-30% of saliva.

What is the main duct of the Parotid Gland called?

Stensen’s Duct.

What is the blood supply for the Parotid Glands?

Branches of the External Carotid Artery.

What is the nerve supply for the Parotid Glands?

Glossopharyngeal Nerve (CN IX).

What is the location of the Submandibular Gland?

• Posterior part of the floor of the mouth, adjacent to the medial aspect of the mandible

  • wrapping around the posterior border of the mylohyoid muscle

What type of cells are found in the Submandibular Gland?

Mixed cells with serous units predominating (5:1). Mucous portions are capped by serous demilunes.

What is the secretion percentage of the Submandibular Glands?

60% of saliva.

What is the main duct of the Submandibular Gland called?

Wharton’s Duct.

What is the blood supply for the Submandibular Glands?

Facial and lingual arteries.

What is the nerve supply for the Submandibular Glands?

Facial Nerve (CN VII).

What is the location of the Sublingual Gland?

Anterior part of the floor of the mouth, between the mucosa and mylohyoid muscle.

What type of cells are found in the Sublingual Gland?

Mostly mucous cells.

What is the secretion percentage of the Sublingual Glands?

5% of saliva.

What is the main duct of the Sublingual Gland called?

Ducts of Rivinus and Bartholin’s Duct.

What is the blood supply for the Sublingual Glands?

Sublingual and submental arteries.

What is the nerve supply for the Sublingual Glands?

Facial Nerve (CN VII).

What is the main function of the salivary glands?

To secrete saliva, which helps with lubrication, digestion, and protection of oral tissues.

What is the importance of the Stensen’s Duct?

It opens opposite the maxillary second molar and carries saliva from the Parotid Gland.

What is the significance of the Wharton’s Duct?

It opens beneath the tongue at the sublingual caruncle, carrying saliva from the Submandibular Gland.

What is the significance of the Ducts of Rivinus?

A series of small ducts that open along the sublingual fold, responsible for saliva secretion in the Sublingual Gland.

Where are minor salivary glands located?

Embedded in the submucosa underneath the oral epithelium, scattered throughout the oral cavity.

What is the estimated number of minor salivary glands?

Approximately 600-1000.

Where are minor salivary glands absent?

In the gingiva and the anterior part of the hard palate.

What type of glands are the minor salivary glands?

Predominantly mucous glands, except for the lingual serous glands (von Ebner's Glands).

Where do von Ebner's Glands open?

Into the troughs of the circumvallate papillae and the foliate papillae on the sides of the tongue.

What are the parenchymal elements of the minor salivary glands?

Composed of terminal secretory units (secretory acini), duct system, and excrete the final product into the oral cavity.

What is the role of the connective tissue (stroma) in the minor salivary glands?

Forms a capsule around the gland, and supports the secretory units & ducts, containing blood and lymph vessels.

What does the basic histologic structure of a salivary gland resemble?

A bunch of grapes, with ducts representing the stems and acini representing the grapes.

How is the duct system structured in minor salivary glands?

A series of branched ducts terminating in spherical or tubular secretory end pieces (acini).

What are the main ducts involved in the secretion process?

Main excretory duct divides into smaller interlobar and intralobular ducts, with striated ducts being the main intralobular component.

What are intercalated ducts in minor salivary glands?

Ducts that connect the secretory end pieces with the striated ducts.

What are intracellular canaliculi in minor salivary glands?

Extensions of the lumen of the end piece between adjacent secretory cells.

What are the main types of cells in the terminal secretory units of the salivary glands?

1. Serous cells

2. Mucous cells

3. Myoepithelial cells.

What are serous cells specialized for?

Synthesis, storage, and secretion of proteins.

What is the shape of serous cells?

Pyramidal in shape, with a broad base resting on a thin basal lamina and a narrow apex bordering the lumen.

What is the most prominent feature of serous cells?

Accumulation of secretory granules in the apical cytoplasm.

How are serous cells arranged in the secretory end pieces?

They are typically spherical, with 8-12 cells surrounding a central lumen.

What are mucous cells specialized for?

Synthesis, storage, and secretion of mucus.

What are the main products of mucous cells?

Mucins, which have a protein core (apomucin).

What is the appearance of mucous cells?

The apex appears empty, and the nucleus and cytoplasm are compressed against the base.

How are mucous cells arranged in the secretory end pieces?

Typically in a tubular configuration, appearing round in cross-section with mucous cells surrounding a central lumen.

What are serous demilunes in mucous cells?

A crescent-shaped arrangement of serous cells that cover the mucous cells at the end of the tubule.

What is the staining characteristic of serous cells?

They stain deeply because they are filled with albumin (protein).

What is the staining characteristic of mucous cells?

They appear light and foamy due to carbohydrates in mucin.

What are myoepithelial cells?

Contractile cells that are closely related to secretory and intercalated duct cells.

Where are myoepithelial cells located?

Between the basal lamina and the secretory or duct cells.

What are the shapes of myoepithelial cells?

• Stellate shape (basket cells) when surrounding the end pieces

• Fusiform shape along intercalated ducts

What is the contractile function of myoepithelial cells?

They help expel primary saliva from the end piece into the duct system by contracting.

What are the other functions of myoepithelial cells?

1. Maintain cell polarity and structural organization of the secretory end piece

2. Produce tumor-suppressor proteins

3. Provide a barrier against invasive epithelial neoplasms

What are the two stages in the formation and secretion of saliva?

1. Primary saliva is produced by cells from secretory end pieces (mucous or serous acinus) and intercalated ducts.

2. Final saliva is produced after reabsorption and secretion of electrolytes in the striated and excretory ducts.

What is the composition of primary saliva?

It is isotonic and contains organic compounds and water.

What is the composition of final saliva?

It is hypotonic and reaches the oral cavity after electrolyte modification (e.g., Na, K, Cl, HCO3).

What is the ductal system of the salivary glands?

A network of tubules that progressively increase in diameter from secretory end pieces to the oral cavity.

What are the three classes of ducts in the salivary glands?

1. Intercalated duct

2. Striated duct

3. Excretory duct

What are the functions of the ductal system?

Passage of saliva and active participation in the production and modification of saliva.

What is the sequence of ducts from acinus to the oral cavity?

Acinus → Intercalated duct → Striated intralobular duct → Interlobar duct → Main excretory duct → Excretory duct.

AISIME

What is the role of intercalated ducts?

They collect primary saliva produced by the acinus and are lined by simple cuboidal epithelium and myoepithelial cells.

What is the diameter of intercalated ducts?

The diameter of intercalated ducts is smaller than that of striated ducts, and the lumina are larger than those of the secretory end pieces.

What are striated ducts?

The largest portion of the duct system, mainly located in the lobules of the gland, consisting of columnar cells with centrally placed nuclei.

What is the important function of striated ducts?

They modify primary saliva by reabsorbing and secreting electrolytes.

What are interlobular/excretory ducts?

Larger in diameter than striated ducts, with pseudostratified epithelium near the lobules and may become stratified near the oral opening.

Where are interlobular/excretory ducts located?

They are located in the connective tissue septa between the lobules of the gland.