Gall Bladder and Pancreas Flashcards Preview

Histology > Gall Bladder and Pancreas > Flashcards

Flashcards in Gall Bladder and Pancreas Deck (20):

Biliary Tract

- Bile canaliculi in the liver for into a larger bile duct
- becomes the common hepatic duct
- cystic duct (connected to gallbladder) merges with the common hepatic duct to form the common bile duct
- Pancreatic duct (from the pancreas) merges with the common bile duct at the sphincter of Oddi
- The sphincter of Oddi opens into the duodenum



- Line the hepatic, cystic and common bile ducts
- Under the influence of secretin
- secretin stimulates cholangiocytes to secrete water and bicarbonate into the bile in order to akalize the contents


Sphincter of Oddi

- opens and closes to control flow of fluids into duodenum - biliary and pancreatic fluids
- When it is closed it causes bile to back up and accumulate in the gall bladder
- CCK causes the Sphincter of Oddi to relax allowing bile to enter the duodenum



- Has ridges - epithelium thrown into folds
- Simple columnar epithelium

- Does not make bile
- mixes up the contents that make up bile
- It stores, concentrates and releases bile

- Smooth muscle - contraction and relaxation facilitates the expulsion of bile from the gallbladder

- CCK causes the smooth muscle cells in the gall bladder to contract - squeezes the fluid from the gallbladder down into the intestine



- Makes fats soluble - emulsifying fats so that they can be metabolized and taken up in the intestine
- waste excretion - bilirubin
- 90% of bile is reclaimed (recycled)
- promotes reabsorption of fat and carries bilirubin to the duodenum
- bilirubin gives brown color to feces


Bile Concentration

- Done through water reabsorption
- Na pumps on lateral membrane
- Na can form a micelle with water
- around the Na ion, a ring of water molecules attaches to it

- as you pump Na out, water goes with it, into blood vessels

- concentrates the bile by absorbing water from lumen of gall bladder


Cystic Duct

- Duct immediately adjacent and connected to the gall bladder
- Thrown into spiral folds
- keeps the cystic duct open at all times - cannot collapse


Ileum Resorption

- 90% of bile acids and biliary fluid are reabsorbed (recycled)
- secreted back into the bile canaliculi of the liver



- 90% Exocrine Cells - Serous acinar glands

- 10% Endocrine - islets of langerhaans

- pancreatic duct converges with common bile duct at the sphincter of Oddi


Exocrine Portion

In the center of the acini
- Have centroacinar cells
- At the end of intercalated ducts
- ducts drain the various enzymes and products being produced by the acini



- proenzymes
- not immediately active so they don't digest the cells of the pancreas
- further processed later to become active



- Stimulate the pancreas to release zymogens
- also contraction of gallbladder and relaxation of the sphincter of Oddi



- targets centroacinar and intercalated duct cells to promote water and bicarbonate secretion
- flushing an alkaline fluid from the pancreas into the duodenum
- also stimulates cholangiocytes in biliary ducts to secrete water and bicarbonate into the bile


Prevention of Autodigetion in the Pancreas

Pancreas secretes proenzymes
- trypsinogen - breaks down proteins into amino acids
- amylase - breaks down starch and glycogen into small sugars
- lipase - breaks down fats into smaller fatty acids

- released as inactive form
- bound by a membrane so they aren't immediately available to start digesting products
- Copacked with trypsin inhibitors - can convert the zymogen form into active form within membrane
- certain enzymes in the duodenum are needed to help activate the proenzymes


Endocrine Pancreas

- islets of langerhans
- Contain Alpha, Beta, Delta and PP cells


Alpha Cells

- secrete glucagon
- promotes increase in blood glucose levels


Beta Cells

- Secrete insulin into the blood
- Decrease blood glucose levels


Insulin Formation

- Insulin is made as a larger promolecule
- chunk of it is clipped off
- small peptides are linked together by disulfide bonds
- Creates mature form of insulin
- Activates insulin

- These post translational changes occur in the RER and Golgi before the final insulin molecule is formed


Delta Cells

- Secrete somatostatin
- inhibits the function of other cells
- also feeds back to inhibit growth hormone


Pancreatic Polypeptide Secreting Cells

- PP cells
- secrete pancreatic polypeptide which may inhibit the exocrine pancreas