HISTEM W7 Oralfacial Glands - Salivary Glands

What are the 4 characteristics used to classify exocrine glands?

1. Duct system

2. Shape of secretory unit

3. Mode of secretion

4. Nature of secretion

What are the 2 types of ducts used to classify exocrine glands?

1. Simple → one duct, no branching

2. Compound → branching duct, secretory unit empties into smaller ducts which join to form larger duct

What are the 4 classes of Simple type Exocrine ducts?

1. Tubular

2. Branched Tubular

3. Coiled tubular

4. Branched alveolar

What are the 2 classes of Compound type Exocrine duct?

1. Tubular

2. Alveolar

What are the 2 shapes of the secretory unit?

1. Unicellular → goblet cell

2. Multicellular → Tubular, Alveolar/Acinus

What are the 3 modes of secretion used to classify Exocrine glands? Describe each.

1. Merocrine

   • secretes through free surface

   • no loss of cytoplasm (exocytosis)

   • ex. Salivary glands, pancreas

2. Apocrine

   • secrete small amounts of cytoplasm/cell with secretory product

   • apical portion of gland pinches off

   • ex. Mammary glands

3. Holocrine

   • entire cells are discharged as secretion

   • ex. sebaceous gland

What are 3 types of secretions used to classify Exocrine glands?

1. Serous → contains digestive enzymes (amylase - breaks down carbs)

2. Mucous → contains mucin (glycoprotein)

3. Mixed → mix of both

What are Acini/Acinus?

Acini are small, rounded clusters (like grapes) of secretory cells in a gland.

• Located at the terminal part of gland connecting to the ductal system

• Single layer of CUBOIDAL epithelial cells surrounding a lumen (central opening)

• Saliva is deposited into the lumen

What is the classification for Salivary glands?

Compound Tubular-Alveolar MEROCRINE gland.

What structures make up the Salivary gland?

1. Capsule →connective tissue; 20% of gland volume

2. Lobes

3. Lobules → contain the glandular units with acini

4. Septa → interlobar septa and interlobular septa

The duct attached to an acinus is called?

intercalated duct

*acini are terminal ends

Describe Intercalated ducts of salivary glands

Intercalated ducts

• Hollow tube attached to acinus

• lined with simple cuboidal epithelium

• do not produce secretions

• serves as passageway for saliva

Describe Striated ducts of salivary glands. What makes them striated?

• connected to intercalated ducts

• lined with simple columnar epithelium

• cells may have basal striations (basal infoldings of the plasma membrane packed with mitochondria.)

• serves as passageway for saliva

• cells resorb and excrete electrolytes

Describe the changes in epithelial cell type of Excretory/Secretory ducts in Salivary glands.

Pseudostratified Columnar → Stratified Cuboidal → Stratified squamous (in oral cavity)

What is the difference between major salivary glands and minor salivary glands?

Major:

• carries secretions some distance into the oral cavity by a MAIN DUCT

• secretes 90% of saliva

Minor:

• empties products directly into oral cavity by SHORT DUCT

What are serous demilunes?

Salivary glands that are composed of both serous and mucous cells are called serious demilune.

Serous demilunes are compoased of two different types of cells (serous + mucous) arranged together in the same secretory unit:

• Mucous cells form the main body of the acinus

• Serous cells cap the end in a crescent shape (the demilune)

What is the functional unit of the salivary gland called?

Alveolus or acinus.

What are the 3 major salivary glands?

parotid, submandibular, sublingual

Describe the Parotid gland. Where is it located? What does it secrete?

• Largest of the major salivary glands containing only serous acini

• Encapsulated

• Located behind mandibular ramus, anterior and inferior to the ear, between the skin of cheek and masseter muscle.

Secretions: mainly serious, contributes ~25% of saliva into oral cavity

Describe the duct system of the Parotid gland. Where does the duct open in the oral cavity?

Parotid gland duct system = LONG intercalated ducts with SHORT striated ducts

Stenson’s duct(Parotid duct) opens opposite to 17/27 on buccal mucosa at parotid papilla

Describe the Submandibular salivary gland. Where is it located? What does it secrete?

• Second largest of the major salivary glands

• Encapsulated

• contains mixed glands = serous demilune

• Located beneath mandible

Secretions: mainly serous and some mucous secretions; contributing 60-65% of saliva into oral cavity

Describe the duct system of the Submandibular salivary gland. Where does the duct open in the oral cavity?

Submandibular duct system = SHORT intercalated and LONG striated ducts with basal striations

Wharton’s duct (submandibular duct) is located under the tongue near the frenum at the sublingual caruncles.

Describe the Sublingual salivary gland. Where is it located? What does it secrete?

• Smallest major salivary gland

• NO CAPSULE

• mixed glands = mostly mucous

• Located on the floor of the mouth in the sublingual fossa, anterior to the submandibular gland

Secretions: mainly mucous secretions and little serous; contributes ~10% of total salivary volume.

Describe the duct system of the Sublingual salivary gland. Where does the duct open in the oral cavity?

Sublingual salivary gland system = 8-30 minor sublingual ducts opening independently into the oral cavity at the sublingual fold.

Bartholin’s duct = formed by several of the small sublingual ducts; opens into oral cavity at the sublingual caruncles

List the minor salivary glands, its location and what it secretes. (5)

1. Labial → lips → mucous

2. Buccal → cheek → mucous

3. Palatine → hard and soft palate → mucous

4. Lingual → Posterior ?? → mucous

5. Von ebner’s salivary gland → posterior dorsum of tongue/Zcircumvallate papillae → serous

What are the 6 functions of Saliva?

1. Moisten food and bind food together

2. Begin digestion (amylase) of carbohydrates

3. Cleanse mouth and aids in swallowing

4. Important for speech and articulation

5. Remineralization of enamel surface (reverse cavities) with the calcium and phosphate in saliva

6. Regulate pH in the mouth

What are misplaced sebaceous glands in the oral cavity called?

Fordyce Granules → mall, yellowish-white, or slightly reddish bumps in oral cavity

60-70% of adults have them

What is a mucocele?

Accumulation of saliva in the mucosa due to trauma to a minor salivary duct

*mucoepidermoid carcinoma kinda looks like a mucocele but its more commonly located by/at/in the parotid salivary gland

What is a sialolith? What is a ranula?

Salivary stones that block salivary flow

• can cause ranula to form.

Ranula - filled with saliva that has leaked from a damaged salivary gland. This leakage leads to a fluid-filled swelling, often appearing bluish or translucent.

What is Xerostomia?

Dry mouth

• caused by decrease in salivary flow or absent.

Decreased salivary flow = increase in bacteria, calculus increase, increased periodontal disease progression

What is Sjogren’s syndrome?

Sjogren’s syndrome is a chronic autoimmune disease where the immune system attacks salivary and lacrimal glands.

• Main symptoms: Dry mouth (xerostomia) and dry eyes (xerophthalmia)

• Can occur alone (primary) or with other autoimmune disorders (secondary)

• Leads to reduced saliva and tear production