Digestive Glands and Liver Flashcards
What is the main excretory duct of the pancreas?
Duct of Wirsung
What is the accessory duct of the pancreas?
Duct of santorini
What type of epithelium is present in the interlobular ducts?
simple columnar epithelium and goblet cells
What type of epithelium is found in the intercalated ducts?
Low cuboidal.
The cells also have receptors for secretin, and they secrete water and bicarbonate.
What type of glands are acini?
serous glands
What type of cells are acinar cells?
pyramidal serous cells.
What is found in the apical zone of acinar cells?
precursors of the enzymes in pancreatic juice
Trypsin, chymotrypsin, amylase and lipase
What type of epithelium is found in centroacinar cells?
cuboidal epithelium
It is continuous with the epithelium of the intercalated duct.
What enzymes does the acinar cell release?
digestive enzymes. It is stimulated by CCK.
What type of fluid is released by epithelial cells in response to secretin?
Bicarbonate-rich, alkaline fluid. It is released by the acinar cells.
Where are digestive enzymes found?
in vesicles by the Golgi
What is the synthesis and secretion of digestive enzymes controlled by?
duodenal enteroendocrine cells.
What are digestive enzymes synthesized as?
Inactive proenzymes on RER of acinar cells
Bicarbonate ion secretion is regulated by what?
secretin.
Bicarbonate is secreted by duodenal enteroendocrine cells when stimulated by food entering the small intestine.
Where does carbon dioxide diffuse out of?
intercalated ducts from the blood.
What are the islets of Langerhans?
Endocrine cell aggregations which are interspersed irregularly among the acini.
They include alpha, beta and delta cells
What are a-cells?
Fine cytoplasmic granules in the islets of Langerhans that form glucagon.
What are b-cells?
cells in the islets of Langerhans that produce insulin.
What are D-cells?
cells in the islet of langerhans that secrete somatostatin, which helps control levels of insulin and glucagon.
What is the general histological organization of the pancreas?
lobulated, compound tubulo-alveolar gland with both and exocrine and endocrine secretory function.
CT divides the gland into small lobules. The lobules contain blood vessels, lymphatics, nerves and excretory ducts.
What is the space of disse?
A region that separates hepatic cells from endothelial cells.
It is active in the transfer between blood and parenchyma
What is the space of mall continuous with?
The space of Disse. It drains into lymphatics.
Glisson’s thin capsule of FECT covers the surface of the parenchyma except for what region?
the diaphragmatic attachment.
What is the classic hepatic lobule?
A lobule with a central venule. Portal triads are at the angles.
What is a portal lobule?
It has three central venules of adjacent lobules that form a triangle.
Portions of the bile of the three lobules drain into the same bile duct.
How many zones are in the liver acinus?
Three zones.
They have hepatic tissue receiving blood from a branch of the hepatic artery conducting blood to opposite central veins.
Where is the portal triad?
It it found at angles (corners) of the classic lobule
What are the components of the portal triad?
branch of hepatic artery (arteriole)
Branch of portal vein (venule)
Bile duct (ductule)
What is found in the cytoplasm of hepatocytes?
glycogen, fat droplets, and pigment granules.
What is found in the basolateral domain of a hepatocyte?
microvilli
They are involved in the absorption of blood-borne substances and the secretion of plasma proteins.
What is found in the apical domain of a hepatocyte?
A bile canaliculus
What is found in the lining of hepatic sinusoids?
Fenestrated endothelial cells
Discontinuous basal lamina
What are perisinusoidal cells?
Cells located in the space of disse that store vtamin A.
They also produce collagen fibers and extracellular matrix components.
What happens do perisinusoidal cells during cirrhosis?
They transform into myofibroblasts and produce type I collagen.
What is the subendothelial space of disse?
space between basal lamina and hepatocytes.
It contains microvilli, collagen, and interstitial fluid that drains into the space of Mall that drains into the lymphatics.
What are Kupffer cells?
phatocytc cells derived from monocytes that line hepatic sinusoids.
What is the bile canaliculus?
Extracellular canal located between two rows of hepatocytes.
It receives bile from hepatocytes.
What is the canal of Hering?
a canal that receives bile from the canaliculus.
It carries bile to the bile ductule.
What are the four components of the gallbladder?
Fundus
Body
Neck
Wall
What are the three layers of the wall of the gallbladder?
mucosa
muscularis externa
submucosa
What type of epithelium is found in the mucosa of the gallbladder?
tall columnar with a striated border
What are Rokitansky-Aschoff sinuses?
small regions of the mucosa with extend into muscular and perimuscular layers.
They may indicate pathological change.
What is found in the muscularis externa?
Layers of smooth muscle separated by layers of CT
What is found in the serosa?
A broad, perimuscular CT coat that is rich in blood and lymphatic vessels and elastic fibers.
What are the major ducts found in the gallbladder?
Cystic duct
Hepatic duct
Common bil duct
The ducts of the mucosa are lined with what type of epithelium?
Columnar epithelium
What are the afferent blood vessels found in the liver?
portal vein
hepatic artery
What do branches of the portal vein enter into?
The lobule.
They then empty into the hepatic sinusoids.
What do the hepatic sinusoids converge into?
A centeral vein (efferent vessel)
What do the central veins unite to form?
A sublobular vein (tributary of the hepatic vein)
What are some of the functions of the liver?
Removal of bile
Storage of glycogen
Conversion of fats and proteins to carohydrates
Amino acid deamination
What does the liver metabolize and store?
fat
What plasma proteins are stored in the liver?
fibrinogen, prothrombin and albumin
What essential vitamins does the liver store?
A, D, B2, B3, B4, B12, K
The liver serves as a ____ organ.
embryonic hematopoietic
The liver also serves as an important organ for ___ metabolism and detoxifying ___
ethanol
drugs, steroids, vitamins A & D, fatty acids and carcinogens.
What is the alcohol dehydrogenase pathway?
Ethanol -> acetaldehyde -> acetate
acetaldehyde is also involved in hepatocyte injury
What organ produces and secretes hepatic bile?
the liver
What are the components of bile?
bile acids
water and electrolytes
cholesterol and phospholipids
pirgments and organic molecules (bilirubin)
Bilirubin is formed from what molecule?
Hemoglobin. It is released from damaged RBCs
What is hemoglobin phagocytized by?
macrophages.
When hemoglobin has been phagocytized by macrophages, what does it split into?
globin and heme
What enzyme converts heme into biliverdin?
heme oxygenase
Free bilirubin is transported attached to what protein as it travels to liver hepatocytes?
plasma albumin
Once free bilirubin is released from plasma albumin, what occurs to it?
It is released within the liver cells and conjugated into bilirubin glucuronids (80%), bilirufin sulfate (10%) and other substances.
Where is conjugated bilirubin secreted?
Into the intestine.
What is conjugated bilirubin in the intestince converted into?
urobilinogen
What are the fates of urobilinogen?
oxidized into excreted products OR
Reabsorbed into the blood and carried back to the liver to be
Reexcreted by the liver OR excreted in the urine.
