Lecture #36: Digestive Glands and Liver I

Question 1

Describe the general histological organization of the pancreas.

Answer 1

lobulated, compound, tubulo-alveolar gland with both as exocrine and an endocrine secretory function

Question 2

What type of gland is the pancreas? Also, does it have endocrine or exocrine secretory function?

Answer 2

• Gland -> lobulated, compound, tubulo-alveolar gland
• Has both exocrine and endocrine secretory function

Question 3

What does the delicate connective tissue of the pancreas contain ?

Answer 3

• The delicated CT contains:
  
  • blood vessels
  • lymphatics
  • nerves
  • excretory ducts

Question 4

What is the main excretory duct of the pancreas known as?

Answer 4

Duct of Wirsung

Question 5

What is the name of the smaller accessory duct of the pancreas?

Answer 5

Duct of Santorini

Question 6

What kind of epithelium are interlobular ducts of the pancreas lined with ?

Answer 6

simple columnar epithelium and goblet cells

Question 7

What type of epithelium are intercalated ducts of the pancreas lined with?

Answer 7

low cuboidal cells

Question 8

What do the cells of the intercalated ducts of the pancreas secrete ?

Answer 8

• water
• bicarbonate ion

Question 9

What receptor for which hormone is found in cells of the intercalated duct of the pancreas?

Answer 9

cells with receptors for SECRETIN

Question 10

Acinus Structure

Answer 10

• Acini are serous
• Acinar cells are pyramidal serous cells
• Centroacinar cells
• NO striated ducts
• NO myoepithelial cells
• Release of digestive enzymes from serous acinar cells is stimulated by CCK
• Bicarbonate-rich, alkaline fluid is released by ductal epithelial cells in response to secretin

Question 11

What is the function of acinar cells?

Answer 11

• Acinar Cells are Pyramidal Serous Cells:
  
  • basal zone which is basophilic and contains nucleus and RER
  • apical zone with zymogen granules
    
    • precursors of the enzymes in pancreatic juice
    • trypsin, chymotrypsin, amylase, and lipase
    • specific receptors for cholecystokinin

Question 12

What is the function of centroacinar cells?

Answer 12

• form a truncated cuboidal epithelium within the lumen of acini
• continuous with the epithelium of the intercalated duct
• unique to pancreas

Question 13

What hormone stimulates the release of digestive enzymes by serous acinar cells?

Answer 13

CCK

Question 14

What do ductal epithelial cells release?

Answer 14

bicarbonate-rich, alkaline fluid

Question 15

Which hormone stimulates the release of bicarbonate-rich, alkaline fluid by ductal epithelial cells?

Answer 15

Secretin

Question 16

Do acini of the pancreas have striated ducts or myoepithelial cells?

Answer 16

NO

Question 17

What is the synthesis and secretion of digestive enzymes controlled by?

Answer 17

peptides secreted by duodenal enteroendocrine cells

Question 18

Where are inactive proenzymes synthesized at in the pancreas?

Answer 18

Digestive enzymes are synthesized as inactive proenzymes on the RER of acinar cells.

Question 19

Where are digestive enzymes stored at in the pancreas?

Answer 19

concentrated and stored in vesicles by Golgi

Question 20

What hormone regulates the secretion of bicarbonate ions?

Answer 20

secretin

** secreted by duodenal enteroendocrine cells when stimulated by food entering the small intestine **

Question 21

What is the synthesis of bicarbonate ion mechanism?

Answer 21

• carbon dioxide diffuses into intercalated ducts from blood
• carbon dioxide + water –> carbonic acid (requires carbonic anhydrase)
• carbonic acid dissociates into bicarbonate and H+
• bicarbonate ion is actively transported to lumen of intercalated duct
• sodium and hydrogen ions are exchanged with sodium flowing into duct lumen and hydrogen flowing into the blood

Question 22

True or False:

The intercalated duct is a continuation into the connective tissue stroma ofthe centroacinar cells.

Answer 22

True

Question 23

Which 3 cell types are found in the Islets of Langerhans in the pancreas?

Answer 23

• A-cells (alpha cells):
  
  • have fine cytoplasmic granules and are presumed to form glucagon
• B-cells (beta cells):
  
  • have coarse cytoplasmic granules; they are more numerous than alpha cells and produce insulin
• D-cells (delta cells):
  
  • secrete somatostatin, which helps to control levels of insulin and glucagon

Question 24

Which cell type of the Islets of Langerhans of the pancreas secretes somatostatin?

Answer 24

D-cells (delta cells)

Question 25

What does somatostatin, released by delta cells in the pancreas, function to control?

Answer 25

helps to control levels of insulin and glucagon

Question 26

What do beta cells of the pancreas secrete/produce?

Answer 26

insulin

Question 27

Does alpha cells or beta cells have more numerous granules?

Answer 27

beta cells

Question 28

What does alpha cells of the pancreas form/secrete?

Answer 28

glucagon

Question 29

Which cell type found in the Islets of Langerhans in the pancres has fine cytoplasmci granules and which has coarse cytoplasmic granules?

Answer 29

• Fine Cytoplasmic Granules = alpha cells
• Coarse Cytoplasmic Granules = beta cells