Digestive Glands and Liver I Flashcards
What type of gland is the pancreas?
tubulo-alveolar with exocrine and endocrine secretory function
Connective tissue support of the pancreas
no organized capsule, thin layer of CT dividing into many small lobules and containing blood vessels, lymphatics, nerves and excretory ducts.
Main excretory duct in the pancreas
Duct of Wirsung
Smaller excretory duct in the pancreas
Duct of Santorini
Interlobular ducts epithelium
simple columnar w/ goblet cells
Intercalated ducts
lined w/ low cuboidal cells: cells w/ receptors for secretin, cells secrete water and bicarb ion.
Structure of Acinar cells
pyramidal serous cells; no striated ducts, no myoepithelial cells.
Basal zone of acinar cells
basophilic and contains nucleus and RER
Apical zone of acinar cells
has zymogen granules; precursors of the enzymes in pancreatic juice; trypsin, chymotrypsin, amylase and lipase. Specific receptors for cholecystokinin.
Centroacinar Cells
Form a truncated cuboidal epithelium w/i the lumen of acini. Continuous w/ the epithelium of the intercalated duct. Unique to pancreas.
What stimulates the release of digestive enzymes from serous acinar cells?
CCK
What regulates secretion of bicarb ions?
secretin - secreted by duodenal enteroendrocrine cells when stimulated by food entering small intestine
Synthesis of bicarb ions
CO2 diffuses into intercalated ducts from blood; CO2 + H2O –> H2CO3 (requires carbonic anhydrase) H2CO3 –> HCO3- + H+
HCO3- is actively transported to lumen of intercalated duct. Na+ and H+ are exchanged w/ Na+ flowing into duct lumen and H+ flowing into blood.
Islets of Langerhans
Endodermal-derived endocrine cell aggregations which are interspersed irregularly among the acini.
A-cells (alpha cells)
have fine cytoplasmic granules and are presumed to form glucagon.
