Salivary Glands

Most saliva produced by

major (extrinsic) salivary glands

• located outside oral cavity

How much saliva does the mouth produce a day

1500 ml/day can be produced

• Cleanses mouth

• Dissolves food chemicals for taste 

• Moistens food; compacts into bolus 

• Begins breakdown of starch with enzyme amylase

Minor salivary glands are

• scattered throughout oral cavity; keep mouth moist 

Major salivary glands include:

-Parotid

-Submandibular

-Sublingual

Parotid -

• anterior to ear and external to masseter muscle 

  • Parotid duct opens into oral vestibule next to second upper molar

Submandibular:

• medial to body of mandible

  • Duct opens at base of lingual frenulum

Sublingual:

• anterior to submandibular gland under tongue

  • Opens via 10–12 ducts into floor of mouth

Salivary glands are composed of two types of secretory cells

• Serous cells: produce watery secretion, enzymes, ions, bit of mucin

• Mucous cells: produce mucus

  Parotid and submandibular glands contain mostly serous cells, but sublingual gland consists mostly of mucous cells

Composition of saliva

• Mostly water (97–99.5%), so hypo-osmotic

• Slightly acidic (pH 6.75 to 7.00)

• Electrolytes: Na⁺, K⁺, Cl⁻, PO₄²⁻, HCO₃⁻ 

• Salivary amylase and lingual lipase 

• Proteins: mucin, lysozyme, and IgA

• Metabolic wastes: urea and uric acid

• Lysozyme, IgA, defensins, and nitric oxide from nitrates in food protect against microorganisms

Teeth

lie in sockets in gum-covered margins of mandible and maxilla

Mastication:

process of chewing that tears and grinds food into smaller fragments

deciduous teeth, or milk or baby teeth

• Primary dentition consists of 20  teeth

• that erupt between 6 and 24 months of age

permanent teeth

-32 deep-lying

-develop while roots of milk teeth are resorbed from below, causing them to loosen and fall out

Teeth are classified according to shape:

• Incisors: chisel shaped for cutting 

• Canines: fanglike teeth that tear or pierce

• Premolars (bicuspids): broad crowns with rounded cusps used to grind or crush

• Molars: broad crowns, rounded cusps: best grinders

  • During chewing, upper and lower molars lock together, creating tremendous crushing force

Molars:

• broad crowns, rounded cusps: best grinders

  • During chewing, upper and lower molars lock together, creating tremendous crushing force

Premolars (bicuspids):

broad crowns with rounded cusps used to grind or crush

Canines

fanglike teeth that tear or pierce

Incisors:

chisel shaped for cutting 

Dental formula;

• shorthand indicator of number and position of teeth

  • Shows ratio of upper to lower teeth for only half of mouth; other side is mirror image