1. glands and openings
   1. Parotid
      1. Stensons duct
         1. Opens near maxillary 2nd molar in the buccal mucosa
   2. Submandibular
      1. Wharton's duct
         1. Opens at the side of lingual frenum (caruncula sublingualis)
   3. Sub lingual
      1. a) Bartholins duct
         1. Opens near submandibular duct.
      2. b) Several minor ducts
         1. Open along the sublingual fold independently.
2. saliva
   1. features
      1. PH of saliva varies from 6.7 7.4 whereas parotid saliva may have a greater range, from 6.0 - 7.8. The primary buffering system of saliva is formed by bicarbonate.
      2. The whole amount of saliva secreted daily by humans is 750 ml
         1. 60% is produced by submandibular glands
         2. 30% by parotids
         3. 5% from sublingual
         4. 7% from the minor salivary glands.
      3. The total volume of saliva secreted daily by humans is approximately 750ml, of which 60% is produced by the submandibular glands, 30% by the parotid, 5% from the sublingual and 7% from the minor salivary gland.
      4. Water accounts for 99% or more of the saliva and the inorganic ions, secretory proteins, and glycoproteins make the remaining 1%.
      5. The major inorganic ions of the saliva are Na+, K+ Cl and HCO,. The Bicarbonates, forms the primary buffering system of saliva.
      6. The pH of saliva varies from 6.7 to about 7.4. Parotid
      7. saliva may have a greater pH of 6.0 to 7.8.
      8. Saliva participates in digestion by providing a fluid environment for solubilization of food and through the action of amylase and lingual lipase enzymes.
      9. Amylase enzyme acts on carbohydrates to produce glucose and maltose.
         1. Its action continues for up to 30 minutes in the stomach before the amylase is inactivated by the acid PH and proteolysis.
   2. Composition
      1. Water accounts for about 99% of saliva.
      2. Glycoprotein
         1. Lubrication pellicle formation
      3. Bicarbonate
         1. Buffer (neutralization of acid, maintains pH)
      4. Amylase
         1. Digestive enzyme
      5. Gustin
         1. Taste
         2. IgA
      6. Lactoferrin
         1. Lysozyme
      7. Peroxidase
         1. Antibacterial action.
   3. Functions of saliva
      1. a) Oral Cavity
         1. Prevents desiccation
         2. • Washing action to flush away debris and bacteria Lubrication
         3. Protects chemical and thermal insult
         4. Buffering capacity due to bicarbonates, phosphates and proteins
         5. Proline rich proteins, glycoproteins, statherin promotes remineralisation
         6. Antibacterial action from peroxidases, Thiocyanate, which catalyses the formation of hypothiocyanate ion. Lysozyme, immunoglobulins, lactoferrin also contribute this action.
         7. Tissue repair
      2. b) Digestion
      3. c) Mastication and deglutition
      4. d) Taste perception
         1. Salty taste is elicited by ionized salts, mainly by the sodium ion concentration.
         2. Sour taste is caused by acidic substances that is by the hydrogen ion concentration.
            1. The more acidic the food, the stronger the sour sensation.
         3. Sweet taste is caused by organic chemicals such as sugars, glycols, alcohols, ketones etc.
         4. Bitter taste is caused by organic substances that contain nitrogen, alkaloids like quinine, caffeine, strychnine and nicotine
      5. e) Speech
      6. g) Excretion
3. points to remember
   1. types of salivary glands
      1. Purely mucous
         1. Glosso palatine
         2. Palatine
         3. Anterior lingual glands
            1. Anterior lingual glands (Glands of Blandin and Nuhn) are chiefly mucous
         4. Apex of the cells appear empty except for thin strands of cytoplasm forming a trabecular network Nucleus and the rims of cytoplasm are compressed against the base of the cell
      2. Purely serous
         1. Parotid-
         2. Pyramidal with broad base on the basement membrane and apex towards lumen Spherical nucleus placed at basal region
      3. Mixed
         1. Submandibular (mainly serous)
         2. Sublingual (Mainly mucous)
         3. Labial and buccal glands
         4. Posterior lingual glands.
            1. Posterior lingual serous glands are called Von Ebner's glands. Vonebners glands are purely serous, and are present in between muscle fibres of tongue below vallate papillae.
      4. Carmal’s gland - retromolar minor salivary gland
   2. General feature
      1. Main function of salivary duct -To convey the saliva secreted by the terminal secretory units to oral cavity
      2. Within a lobule, the smallest ducts are the intercalated ducts.
         1. The lumen of intercalated duct contains Na, Cl and K and HCO, ions.
         2. The luminal and basolateral membranes of the end pieces and intercalated ducts have abundant transporters that function to produce a net reabsorption of Na+ and Cl- resulting in formation of hypotonic saliva.
         3. The ducts also secrete K+ and HCO3- but little if any secretion and reabsorption of water occurs in striated or excretory ducts.
      3. The concentration of Na and Ct ions is similar to that of plasma. The K ions concentration is greater than plasma and the concentration of HCO, is variable depending on specific gland.
      4. Glands of Blandin and Nuhn are anterior lingual glands located near apex of tongue. They are chiefly mucous in nature. The ducts open on the ventral surface of the tongue near the lingual frenum.
      5. The posterior lingual glands are mixed in nature. The posterior serous glands are called von Ebner's glands and are located between muscle fibres of the tongue, below the vallate papillae.
      6. Their ducts open into the trough of the vallate papillae and at the rudimentary foliate papilla on the sides of the tongue.
      7. Glossopalatine and palatine glands are purely mucous in nature. The labial and buccal glands are mixed in nature
      8. Demilune is a combination of serous and mucous unit in which mucous cells are capped by several serous cells.
      9. Muciramine and Mucihematen are the two dyes that are used for non-specific staining of mucins.
      10. PAS technique is used to identify neutral mucins. Alcian blue, toluidine blue, coloidal iron and aldehyde fuschin methods are used to localize the acid mucins.
   3. myoepithelial cells
      1. Myoepithelial cells are stellate shaped and are also known as "basket cell". The structure of myoepithelium is similar to that of smooth muscle and contains actin, myosin and related proteins.
      2. Myoepithelial cells have contractile function.
         1. They help in expelling of secretions from the lumina of secretory units.
      3. Related to secretory and intercalated duct cells
         1. Contains cytokeratin intermediate filament and contractile actin filaments
      4. Functions:
         1. Contractile process
         2. Accelerate outflow of saliva from acini
         3. Shorten and widen intercalated ducts
         4. Supports parenchyma
         5. Contribute to secretory pressure in the acini or duct.
         6. Provide signals to the acinar secretory cells for structural organization
   4. nerve supply
      1. The parasympathetic (secretomotor) supply to Submandibular and sublingual salivary glands is through chordatympanic nerve and that of parotid gland is through glossopharyngeal nerve.
      2. Parasympathetic stimulation produces copious, watery saliva while the sympathetic stimulation produces thicker, and less quantity of saliva.
   5. Tuft cells
      1. Tuft cells (caveolated or brush cells) are seen in the epithelium of the main excretory duct of salivary glands.
      2. They have long, stiff microvilli and apical vesicles and are thought to be receptors of some type.
      3. The shape of tuft cells varies from pear-shaped, to barrel-shaped and goblet-shaped.
      4. Their proposed function is absorption and chemoreception.