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Block D - Digestion and Metabolism > Histology Lecture 3b -- Salivary Glands > Flashcards

Histology Lecture 3b -- Salivary Glands Flashcards

1
Q

From what are glands derived?

A

Ectoderm or endoderm layers

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2
Q

3 steps in the development of glands

A
  1. The epithelium invaginates into the underlying connective tissue, bringing the epithelial basal lamina with it
  2. The invagination develops a lumen that communicates to the original surface
  3. The invagination differentiates into a secretory unit as its furthest part and a duct that connects the secretory unit to the epithelium
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3
Q

Define exocrine glands

A

Product made by the secretory unit of the gland and is delivered by the duct to the surface from which the invagination occurred

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4
Q

Define endocrine glands

A

The duct loses its connection with the secretory unit and the unit secretes into the connective tissue around it and ultimately into the blood vessels (ductless glands)

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5
Q

3 classes of exocrine glands based on the shape of secretory unit

A
  • Tubular
  • Acinar
  • Alveolar
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6
Q

Define tubular exocrine glands

A

Unifrom diameter for the secretory unit and the duct (i.e. sweat gland)

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7
Q

Define acinar exocrine glands

A

A grape-like secretory unit is attached to a duct (i.e. salivary glands)

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8
Q

Define alveolar exocrine glands

A

A flask-shaped secretory unit, but is not often used because it can be confused with an alveolus of the lung

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9
Q

2 classes of exocrine glands based on the relationship between secretory unit and duct

A
  • Simple = one secretory unit to one duct (i.e. sweat gland)
  • Compound = a branching tree-like system with secretory units at the ends of all the branches (i.e. salivary glands)
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10
Q

4 classes of glands based on the manner in which cells secrete

A
  • Holocrine
  • Merocrine
  • Apocrine
  • Cytocrine
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11
Q

Define holocrine glands

A
  • Entire cell is the secretion product
  • The gland cells become filled with the secretory substance and the cell dies and disintegrates as it forms the secretion product
  • Example = sebaceous glands of the hair
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12
Q

Define merocrine glands

A
  • Secretion based on production of membrane-bound secretory granules that are exocytosed or secreted to the outside of the cell
  • No loss of cell material as membrane is derived from the Golgi apparatus and retrieved by fusion with cell membrane
  • Secretory product is made de novo for export
  • Example = all salivary glands
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13
Q

Define apocrine glands

A
  • A small part of the cell cytoplasm is lost as part of the secretion
  • Example = matrix vesicles from hypertrophic chondrocytes in the cartilaginous growth plate
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14
Q

Define cytocrine glands

A
  • Part of one cell containing the secretory granule is phagocytosed by another cell
  • Example = melanosomes produced by melanocytes phagocytosed by keratinocytes in the skin
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15
Q

3 classes of glands based on the type of secretion product

A
  • Serous
  • Mucous
  • Mixed
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16
Q

Define serous glands

A

Producition of a watery secretion, usually glycoproteins that are enzymes

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17
Q

Define mucous glands

A

Production of a secretion that is high in carbohydrates (about 50% protein, 50% carbs)

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18
Q

Define mixed glands

A

Acinus is composed of both serous and mucous cells, or there is a mucous acinus with a serous demilune

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19
Q

Describe the arrangement of serous cells

A

Usually arranged as acinar secretory units. Their pyramidal shapes are arranged in a spherical unit with the apices of the cells meeting to form a small lumen

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20
Q

How may the luminal surface area of serous glands by increased?

A

Interncellular canalicules between serous cells

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21
Q

Describe the cell base of serous cells

A
  • Basophilic
  • Occupied by abundant parallel cisternae of rER
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22
Q

Describe the apex of serous cells

A
  • Filled with eosinophilic zymogen granules
  • Under certain conditions of poor fixation, the granules may be dissolved, leaving empty vacuoles
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23
Q

Describe the nuclei of serous cells

A
  • Spherical and located towards the base of the cells, usually surrounded by rER
  • Prominent nucleoli (high protein synthesis)
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24
Q

What drains the acini of serous glands?

A

Intercalated duct

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25
Q

How are mucous cells arranged?

A
  • As acinar or tubular secretory units
  • Cuboidal cells arranged around a large lumen
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26
Q

Describe the rim and base of mucous cells

A
  • Rim of darkly stained cytoplasm rich in rER at the base
  • Flattened dark-stained nuclei at base
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27
Q

Describe the apex of mucous cells

A

Filled with large mucinogen droplets or granules, whose proteins have a high sugar content

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28
Q

Why might it be hard to see the lumen of a mucous gland despite it being larger than a serous gland?

A

The secretory product of mucous glands, mucin, fills the large lumen when released and hydrated

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29
Q

How are mucous acini drained?

A

By intercalated or larger ducts

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30
Q

Describe the distribution of cells in mixed acini

A

Most often composed of a mucous acinus capped by a serous demilune (a cap of serous cells sitting on a mucous acinus)

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31
Q

What empties a mixed acinus?

A

The secretions enter a common duct, which may be intercalated

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32
Q

Describe what immediately surrounds all secretory units of glands and why

A

Since all secretory units are epithelially derived, they are surrounded by a basal lamina, which is continuous with the duct and ultimately the epithelium of origin

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33
Q

What lies between basal lamina and the base of secretory units in some acini?

A

Epithelial cells with contractile properties (myoepithelial cells) and therefore contain actin and myosin

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34
Q

3 divisions of duct systems (in sequence)

A
  1. Intercalated
  2. Striated
  3. Collecting
35
Q

Smallest ducts

A

Intercalated ducts

36
Q

Describe the histology of intercalated ducts

A
  • Lined by simple squamous epithelium
  • Very small lumen
  • Difficut to see; only slightly bigger than capillaries
  • Very regular structures with distinctive features
37
Q

Diameter of striated ducts

A

Same as acini

38
Q

Describe the histology of striated ducts (4)

A
  • Regular and round in cross section
  • Lateral borders of their columner or high cuboidal cells are indistinct due to cell interdigitation
  • Round nuclei near the base
  • Deeply eosinophilic cytoplasm that is striated due to extensive basal membrane infolding and elongated mitochondria
39
Q

Function of striated ducts

A

Resorption of useful fluids and ions from the crude glandular secretion

40
Q

Elements of the pumping mechanism in striated ducts

A

Extensive basal membrane infolding and elongated mitochondria

41
Q

Largest ducts

A

Collecting ducts

42
Q

Describe the histology of collecting ducts

A
  • Lined by simple epithelium (cuboidal in small ducts; columnar in larger ducts)
  • Largest duct joins with the epithelium (structure resembles epithelium here) –> secretions
43
Q

What are glandular secretory units organized into?

A

Lobules

44
Q

What are the lobules of glandular secretory units organized into?

A

Lobes

45
Q

Define the capsule of a gland

A

A layer of dense connective tissue covering the outer aspect of the gland

46
Q

How are glands divided into lobes and lobules?

A

Capsular connective tissue that continues into the gland

47
Q

Function of the capsular connective tissue of the glands

A

Carries the blood supply to the glandular units, but also carries the duct system

48
Q

Define intralobular structures of the glands and ducts

A

Structures located within the lobules:

  • Acini
  • Intercalated ducts
  • Striated ducts
49
Q

Define interlobular structures of the glands and ducts

A

Structures leaving the lobules to join to similar structures, such as striated ducts, which being intralobular non-striated ducts that leave the lobules immediately to join with similar ducts –> interlobular

50
Q

Differentiate between intralobular and interlobular collecting ducts

A

Interlobular collecting ducts are larger

51
Q

Differentiate between ducts outside and within a lobule

A

Outside = surrounded by much connective tissue

WIthin = little or no connective tissue around them

52
Q

How are lobes of a gland drained?

A

Large interlobular ducts join to become large collecting ducts that drain the groups of lobules which make up a lobe of gland

53
Q

Define minor salivary glands

A

Small compound glands located throughout the oral cavity beneath the epithelium

54
Q

3 major salivary glands

A
  • Parotid gland
  • Submandibular gland
  • Sublingual gland
55
Q

Largest salivary gland

A

Parotid gland

56
Q

Location of parotid gland

A

Well encapsulated gland located in the side of the face

57
Q

What type of gland is the parotid gland?

A

Pure serous gland

58
Q

What is located between the serous acini of the parotid gland?

A

Deposits of unilocular adipocytes

59
Q

Describe the duct system of the parotid gland

A

Includes intercalated, striated and collecting ducts

60
Q

Location of opening of the main duct of the parotid gland

A

Inside of the cheek, just oppostie to the upper 2nd molar tooth

61
Q

Name of the main duct of the parotid gland

A

Stenson’s duct

62
Q

Salivary gland with the greatest output

A

Submandibular gland

63
Q

2 well-encapsulated major salivary glands

A

Parotid gland

Submandibular gland

64
Q

Composition of the cells of the submandibular gland

A

90% serous acini

10% mucous acini

65
Q

Describe the distribution of the acini in the submandibular gland

A

Mucous acini occur in small patches distributed throughout the gland. Some may be mixed or show serous demilunes

66
Q

Location of the opening of the duct from the submandibular gland

A

Under the tongue

67
Q

Name of the duct of the submandibular gland

A

Wharton’s duct

68
Q

Location of the sublingual gland

A

Either side of the midline of the tongue in the floor of the mouth

69
Q

Major salivary gland that is poorly encapsulated

A

Sublingual gland

70
Q

Describe the composition of the sublingual gland

A

Mixed acini; mainly mucous with serous demilunes

71
Q

Name of duct that empties the sublingual gland

A

Rivinus’ ducts

72
Q

Where do Rivinus’ ducts open?

A

At numerous sites along the connection of the tongue to the floor of the mouth

73
Q

Define xerostomia

A

Dry-mouth; ack of saliva

74
Q

Consequences of xerostomia

A
  • Difficulties in swallowing, tasting and speaking
  • Can increase the chance of dental decay and other infections of the mouth
75
Q

What can cause xerostomia

A

Certain medications (over 400) and medical treatments

76
Q

Particular medications that may cause xerostomia

A

Those used for high blood pressure and depression treatments

77
Q

Medical treatments that may cause xerostomia

A

Radiation therapy and chemotherapy

78
Q

Diseases/pathologies that can affect salivary glands (5)

A
  • Sjogren’s Syndrome
  • HIV/AIDS
  • Diabetes
  • Parkinson’s disease
  • Nerve damage
79
Q

Symptoms related to xerostomia

A

Itchy, scratchy eyes from decreased tears

80
Q

Define Sjogren’s disease

A

An autoimmune disease, where immune defenses destroy acinar salivary gland cells

81
Q

Define sialoliths

A

Stone formation in the salivary glands and their duct system

82
Q

Where can mineralized sialoliths occur most frequently

A

In the submandibular gland and its duct system (but also in other salivary glands and ducts)

83
Q

Typical contents of sialoliths

A

Calcium-phostphate (hydroxyapatite) mineral and incorporated proteins

84
Q

Consequence of sialoliths

A

If they do not pass through the duct system, blockage of ducts requires their surgical removal

Block D - Digestion and Metabolism (29 decks)

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