pak Flashcards
(25 cards)
What are the functions of bile
What are the steps of synthesizing bile?
What is bile mainly composed of?
Bile salts
ions
chloestrol
lecithin (phospholipids)
what is the tonicity of the ion conc in bile to plasma?
It is isotonic
What happens in the canaliculus?
Bile acids enter the cell using the BSEP
HCO3- enters the cell in exchange for Cl- leaving using AE2 channels
Phospholipids passively go inside the cell
Cholestrol passively goes inside the cell
water enters using AQP8
What is the main modification in cholengiocytes?
Secretion of bicarbonate into the bile
What is the difference between cholangiocytes and canaliculi?
Cholangiocytes: Found in the lining of bile ducts
Canaliculi: found in the liver in between hepatocytes
What modifications happen to bile in the bile ducts that are done by cholangiocytes?
- Secretin and VIP activate the cAMP pathway
- cAMP increases the number of CFTR channels
- Cl- ions leave into the lumen, then get reabsorbed through the AE2 in exchange for HCO3- to be released into the lumen into the bile
- 2CL-, Na, and K+ enter the cell from the interstium
- HCO3- enters the cell from the interstitum using the Na+/
- Water flows through aquaporins through the gradient into the lumen
What are the results of the modifications on bile done in the ducts?
1 Bile is more diluted bc of the flow of water
2 Bile is more alkaline due to the secretion of HCO3-
What are the modifications done on bile in the gallbladder?
NaCl- is reabsorbed
H2O is reabsorbed
- Na+/H+ exchanger secretes H+ and absorbs Na+
Cl-/HCO3- exhnager secretes HCO3- and absorbs Cl-
H+ and HCO3-join to form H2O and CO2.
NOTE: H+ is secreted at a faster rate than HCO3-
Does the bile become more acidic or alkaline in the gallbladder?
More acidic bc of the fact that H+ is secreated faster than HCO3- leading to increased acidity.
What are the final modifications to bile done in the gall bladder?
1 Bile is concentrated due to water reabsorption
2 Bile is more acidic due to H+ secretion
What are the differences between the different concentrations of substances between Liver bile and Gallbladder bile
What are the 4 things that are present in the liver bile more than the gallbladder bile?
Water
HCO3-
Na+
Cl+
What does cck stand for?
Cholecystokinen
Chole: Bile
Cysto: Gallbladder
Kinen: to move
What are the steps that lead to the contraction of the gallbladder?
1 fat enters the duodenum and i cells get stimulated to release CCK
2 CCk can act in two ways:
Minor: hormonal, CCK acts on the gall bladder directly
Major: CCK stimulates the vagal afferent nerves which send impulses to the dorsal vagal complex in the brain.
The complex then sends efferent signals to the gallbladder to make it contract and make the sphintcher of oddi relax.
What is the percentage of bile reabsorption and bile production?
5% is produced daily
What is the first step in the reabsorption of bile?
Deconjucation and decaroxylation by flora (reabsorbed passively)
Conjucated bile gets reabsorbed through ASBT channels
What are the channels that conjugated and deconjugated bile acids use to enter the cell?
What are the channels that use ATP?
BSEP
ASBT
What does high portal blood circulation do to bile production?
Decreases bile production bc more bile is getting reabsorbed
What does Low portal blood circulation do to bile production?
Increases bile production bc less bile is getting reabsorbed
How do gallstones form?
Gallstones form from an imbalance in cholestrol to bile acid concentration
What might cause the imbalance between the cholestrol and bile acid?
increased amount of cholestrol in blood
Decreased bile acid in blood
low phospholipid concentration
