Accessory Organs of the GI tract Flashcards
What are the three main digestive glands?
major salivary glands, exocrine pancreas, and the liver
how are the secretory cells organized in salivary glands?
in an acinus
what aids in the release of secretions in salivary glands?
myoepithelial cells
what is the ductal pathway?
acinus–>intercalated duct–> striated duct–> excretory duct
what type of epithelium makes up the intercalated duct?
low cuboidal epithelium
what type of epithelium makes up the striated duct?
simple cuboidal-to-columnar epithelium
what type of epithelium makes up the excretory duct?
simple cuboidal–> pseudostratified columnar or stratified cuboidal
what type of secretory cells do the acini of the parotid glands consist of?
serous secretory cells
what are the characteristics of the parotid gland histologically?
they are pyramidal cells with a basally located nucleus
what type of secretory cells make up the acini of the sublingual gland?
it is a mixed gland, but predominantly mucous
what type of cells make up the acini of the submandibular gland?
serous cells are predominantly found, but mucous cells are present
in the submandibular gland, what are the mucous cells capped by?
a serous demilune (bonnet)
what covers the pancreas?
a thin layer of loose CT- forms a capsule
what is the functional unit of the exocrine pancreas?
the serous acinus
what does the functional unit of the exocrine pancreas contain?
pancreatic acinar cells
what are the duct cells that are found within the acinus of the exocrine prancreas?
centroacinar cells
what do centroacinar cells secrete?
HCO3-, Na+, and H2O–> alkalinizes secretions
what is the hallmark of the exocrine pancreas?
the acinar cells stain intensely, centroacinar cells stain lightly
why is the septa important?
it provides a route for neurovasculature
what does the apical domain of the pancreatic acinar cell contain?
zymogen granules
what do the zymogen granules contain and what is their purpose?
~20 different pancreatic proenzymes- to help complete digestion
what are two examples of pancreatic proenzymes that digest proteins?
trypsinogen, chymotrypsinogen
what is an example of a pancreatic proenzyme that digests carbohydrates?
amylolytic enzymes
what is the liver enclosed in?
thin CT capsule lined with mesothelium of visceral peritoneum
instead of acini, how are hepatocytes arranged?
in cellular cords
the liver structure varies in regard to its functional unit. What are they?
hepatic lobule, portal lobule (when describing bile) and liver acinus (when describing blood flow)
how do hepatocytes look histologically?
large, polygonal cells with pink staining cytoplasm and microvilli
what does the bile that the hepatocytes secrete drain into?
bile canaliculus
what are the bile canaliculi?
spaces located between adjacent hepatocytes
what are the hepatic cords separated by?
hepatic sinusoids
what are the hepatic sinusoids?
where blood flow passes through
the liver parenchyma is organized as hepatic lobules; hepatocytes form irregular plates radiating from what?
a central vein
what are the plates of the hepatocytes supported by?
stroma of reticular fibers
what are the plates of the hepatocytes separated by?
sinusoids
what do the peripheral angles of each lobule contain?
a portal triad
what makes up the portal triad?
venule, arteriole, and bile ductules
what do bile canaliculi drain into?
canals of Hering
what are canals of Hering composed of?
cuboidal epithelial cells called cholangiocytes
what do canals of Hering drain into?
bile ductules
what happens to the bile ductules?
they merge together and enlarge to form the right and left hepatic ducts
what is the biliary tree lined with?
a mucous membrane having a simple columnar epithelium of cholangiocytes
what cells are found within the hepatic sinusoids?
Kupffer cells and hepatic stellate cells (ito cells)
what are kupffer cells?
stellate macrophages; detect and phagocytose defected erythrocytes
what are hepatic stellate cells (ito cells)?
cells with small lipid droplets that store vitamin A and other fat-soluble vitamins
what is the perisinusoidal space?
the space where there is direct bathing of the microvilli with blood from the sinusoid
what does the perisinusoidal space facilitate?
uptake/release of nutrients, proteins, and potential toxins
what is the periportal space?
it is a space that is located at the edges of canals between stromal connective tissue and hepatocytes
what is the purpose of the periportal space?
excess fluid in the perisinusoidal space is collected here to prevent edema
what is the central axis for the portal lobule?
the portal triad (bile duct)
how do you get the portal lobule?
you ID the portal triad, then you draw imaginary lines between 3 central veins (its a triangular block of tissue)
what does the portal lobule outline?
bile drainage pathway from adjacent lobules into the same bile duct
how do you get the hepatic acinus?
you identify two adjacent central veins with portal triads in between
which zone is most susceptible to damage if you block blood flow to a segment of the liver?
zone 3
what does the classic lobule of the liver emphasize?
the endocrine function of the hepatocytes as blood flows toward the central vein
what does the portal lobule of the liver emphasize?
hepatocytes exocrine function and flow of bile
what does the hepatic acinus emphasize?
different oxygen and nutrient contents of blood at different distances along the sinusoids
what is unique about the gallbladder?
there is no muscularis mucosae or submucosa
what can the gallbladder sometimes develop as the result of hyperplasia and herniation of epithelial cells through the muscularis externa?
Rokitansky-Aschoff sinuses
what are rokitansky-Aschoff sinuses?
deep diverticula of the mucosa that may extend through the muscularis externa
