Salivary Glands DLA Flashcards
What is the function of saliva?
Function
• Moistens and lubricates food : mucus and electrolytes
• Protects the oral cavity by lubrication, control of bacterial flora (by the presence of lysozyme, peroxidase, histatin, cystatin, lactoferrin, and IgA), and its cleansing action.
• Assists in taste sensation.
• Initiates digestion of carbohydrates via salivary amylase.
• Weak lipase to digest some fat
How much saliva is produced daily?
Average daily production of saliva is 1.0 to 1.2 liters
What is the composition of saliva?
Composition
• Initial acinar secretion resembles tissue fluid
• Modified by the ductal system
• Intercalated ducts - adds bicarbonate and removes chlorine ions
• Straited ducts - removes sodium and pumps potassium and bicarbonate into the saliva
• Final secretion is hypotonic
• Microbial flora and immune cells
• FYI, also contains: Opiorphin (pain killer) haptocorrin (Vit B12 binding) and Kallikrein (forms bradykinin)
Describe salivary acini (secretory units)
- Blind sac containing secretory cells
- Major salivary gland acini surrounded by a capsule of connective tissue from septa divides the glands into lobes and lobules
What are the basic types of salivary acini?
- Three basic types:
- Serous: contains serous/protein secreting cells.
- Mucous:contains mucous cells
- Mixed: contains both serous and mucous cells. The serous cells are arranged in a cap around the mucous cells called a serous demilune
Describe the mayo epithelial cells of salivary acini
Myoepithelial cells:
• Contractile cells that are located on the basal aspect of the acini and
the proximal part of the ducts.
• Contraction helps move the secretory product out of the acini and into the ducts.
What are the segmental sequences of salivary ducts?
Three sequential segments:
• Intercalated ducts→Striated Ducts→Excretory ducts
The proximal part of the salivary ductal system modify initial secretion and are located between the parenchyma or acini
What is the significance of intercalated ducts?
- Intercalated ducts: leads from the acinus
• Lined by a simple low cuboidal epithelium
• Secrete HCO3- and absorb Cl- from primary secretion
What is the significance striated ducts?
- Striated ducts (S)
• Lined by simple high cuboidal to columnar epithelium
• Basal striations→in-foldings of the basal plasma
membrane, which compartmentalize mitochondria
- Apical nuclei
- Reabsorb Na+ from primary secretions
- Secretion of K+ and adds HCO3- into secretions
What is the significance striated ducts?
- Striated ducts (S)
• Lined by simple high cuboidal to columnar epithelium
• Basal striations→in-foldings of the basal plasma
membrane, which compartmentalize mitochondria
- Apical nuclei
- Reabsorb Na+ from primary secretions
- Secretion of K+ and adds HCO3- into secretions
What is the significance of excretory ducts?
Excretory ducts (Ex): empties into the oral cavity
- Location: interlobular and interlobar connective tissue.
- Epithelium: simple cuboidal / columnar which gradually changes to pseudostratified columnar, stratified cuboidal or columnar and even stratified squamous epithelium near the oral cavity
Describe the parotid gland
Located anterior and inferior to the ear
- Classified as a pure serous, compound, alveolar gland
- Has a capsule formed by the superficial cervical fascia→ dense connective tissue which forms of trabeculae (septa) that subdivide the gland into lobes and lobules.
- Trabeculae convey blood and lymph vessels, excretory ducts, and nerves through the substance of the gland.
Describe the parotid gland
Located anterior and inferior to the ear
- Classified as a pure serous, compound, alveolar gland
- Has a capsule formed by the superficial cervical fascia→ dense connective tissue which forms of trabeculae (septa) that subdivide the gland into lobes and lobules.
- Trabeculae convey blood and lymph vessels, excretory ducts, and nerves through the substance of the gland.
Describe the secretory portion of the parotid gland
Secretory portion
• Serous acini- serous cells produce amylase
• Apical secretory granules
• Granules also contain peroxidase, lysozyme, cystatins
• Myoepithelial cells around acini
Descrbe the ducts of the parotid gland
Ducts
• Intercalated ( ID) and striated ducts (SD)
• The parotid gland has the longest intercalated ducts
What is the significance of Stenson’s duct to the parotid gland?
Stensen’s Duct
- Largest excretory duct (main parotid duct).
- Opensintotheoralvestibuleat the parotid papilla (next to the upper second molar tooth).
Describe the submandibular gland
Located on either side of the floor of the mouth close to the mandible
• Classified as a mixed, compound, tubuloalveolar gland
Describe the secretory portion of the submandibular gland
Secretory portion
- Composed mostly of pure serous acini
- However, groups of mixed acini are also present among the pure serous units.
- Note the presence of dense serous cells forming demilunes and pale-staining mucous cells grouped along the tubular portion of this tubuloacinar gland.
- Myoepithelial cells around acini
Describe the ducts of the submandibular gland
Ducts
- Intercalated ducts are short, but present
- Striated ducts are long and clearly evident.
- Excretory submandibular ducts open on either side of the base of the lingual frenulum.
Describe the sublingual gland
- Located on the floor of the mouth anterior and lateral to the submandibular gland
- Classified as a mixed, compound, tubuloalveolar gland
Describe the secretory portion of the sublingual gland
Secretory portion
• Mixed acini
• Pure mucous acinus
• Myoepithelial cells around acini
Describe the ducts of the sublingual gland
Ducts
• Short intercalated and striated ducts but are few in number
• Multiple excretory sublingual ducts empty directly into the floor of the oral cavity and into the submandibular duct
