Bile, Gallbladder And Gallstones Flashcards
What is the ampulla of vater?
Where the common bile duct and the pancreatic duct join
What does the gallbladder do?
Stores and concentrates bile
How does the gallbladder concentrate bile?
Sodium ions and water are actively transported out and H+ is transported in
What does pancreatic juice contain?
Bile salts, bile pigments and dissolved substances in alkaline electrolytes
What are cholangiocytes?
Specific light junctions for adding water to bile
What happens in the ductules of the liver?
Glucose and amino acids are scavenged, GSH is hydrolysed and IgA, HCO3- and water are secreted
When are HCO3- and water secreted into the ductules?
In response to secretin in the postprandial period
When is the most bile being secreted?
During and after a meal
What influences the secretion of bicarbonate and water?
Secretin and ACh
What happens if there’s increased bile salt in the blood?
Increased bile salt synthesis and secretion into the bile canniculi
When does the sphincter of oddi contract and relax?
Contracts during fasting periods and relaxes during and after meals
Where is the sphincter of oddi found?
Where the bile duct reaches the duodenum
What can be secreted across the bile cannicular membrane?
- bile acids
- phosphatidylcholine
- conjugated bilirubin
- cholesterol
- xenobiotics
What are xenobiotics?
Foreign stuff
What substances can enter bile by diffusing?
Water, glucose, calcium ions, GSH, amino acids and urea
What % of hepatic bile is water?
97
What else (not water) is in hepatic bile?
Cholesterol, lecithin, bile acids, bile pigments etc
What % of gallbladder bile is water?
89%
Where does bile go when the sphincter of oddi is closed?
To the gallbladder
What are the two biosynthetic pathways for bile acid formation?
Classic (natural) or alternative (acidic) pathway
Which pathway leads to 98% of bile acid formation?
Classic
What are examples of bile acids?
Cholic acid and chenodeoxycholic acid
What are bile acids made from?
Cholesterol
What does conjugation mean for bile acids?
Allows them to be secreted and decreases their cytotoxicity
What are bile acids synonymous with?
Bile salts
What are the four major bile acids in humans and their proportions?
Cholic acid (50%) Chenodeoxycholic acid (30%) Deoxycholic acid (15%) Lithocholic acid (5%)
Which bile acids are formed in the liver and what type of bile acid are they?
Primary
Cholic acid and chenodeoxycholic acid
Which bile acids are formed in the colon and what type of bile acids are they?
Secondary
Deoxycholic acid and lithocholic acid
What are the major functions of bile?
- elimination of cholesterol to bile acids
- reduce cholesterol precipitation in gallbladder
- facilitate fat soluble vitamin absorption
- regulate their own transport and metabolism
- facilitate the digestion of triglycerides
What makes cholesterol more soluble in bile?
Bile acids and phospholipids
Which vitamins are fat soluble?
A, D, E and K
What does bile work together with that ensures the emulsification of fats?
Lecithin and monoglycerides
What controls the release of bile?
Contraction of gallbladder
What happens in the cephalic phase?
The taste, smell and presence of food in mouth -> impulses via the vagus nerve
What happens in the gastric phase?
Distension of stomach generates impulses in vagus nerve
What happens in the intestinal phase?
Period of gallbladder emptying
What are some mediators for increased bile release?
CCK, secretin, ACh and ATP
What is CCK released in response to?
Fats
What is ACh released in response to?
Acidic chyme
What is secretin released in response to?
Fats or acidic chyme
What is the nerve signalling pathway to/from the gallbladder?
Vagal afferent -> dorsal vagal complex -> vagal efferents -> chemical release
Which molecule can work directly on the gallbladder?
CCK
What % of bile salts are reabosorbed?
95%
How are bile salts reabsorbed?
Through Na+- Bile salt coupled transporters
What happens to the remaining 5% of bile salts?
Returned to the liver and secreted into bile
What is enterohepatic circulation?
Recycling of bile salts
How often is the bile acid pool recycled?
Roughly twice per meal
What happens if enterohepatic circulation is interrupted?
Liver will synthesise too much bile salts
And the kidneys will excrete the synthesised bile salts
What is bile stasis?
A factor for gallstone formation - stones form in bile that is held into the gallbladder rather than bile flowing in the bile ducts into the duodenum
What are some factors involved in gallstones formation?
- Decreased amount of bile acids due to malabsorption
- chronic infection
- super saturation of bile with cholesterol
- presence of nucleation factors or glycoproteins
How long does it take for a gallstone to form in a patient who already suffers from gallstones?
2-3 days
How long does it take for a gallstone to form in a patient who has never suffered from gallstones?
2 weeks
Why does it take so much longer for a gallstone to form in patients who’ve never had gallstones?
Presence of anti-nucleation factors
What are they symptoms of a gallstone being lodged in the opening of the gallbladder?
Right upper quadrant pain and jaundice
What are the symptoms of gallstones lodging at the sphincter of oddi?
Pressure builds up- right quadrant pain and jaundice
What do lodged bile stones cause?
Nutritional deficiency- fats can’t be digested properly
How can you diagnose gallstones?
- Ultrasonography and computer tomography
- cholescintigraphy
- endoscope retrograde cholangiopancreotopography
What happens in ultrasonography and computer tomography?
Explore the right upper quadrant of gallbladder
What happens in cholescintigraphy?
Administer technitium-99 labelled derivative of iminodiacetic acid and then you can get images of the gallbladder and ducts
How does endoscope retrograde cholangiopancreotography work?
Inject contrast media from an endoscope channel and visualise the biliary tree
What percentage of gallstone cases are asymptomatic?
85%
How can gallstones be asymptomatic?
If the gallstones remain in the gallbladder
What causes acute cholecystitis?
If the neck of the cystic duct is impaired
What are the symptoms of acute cholecystitis?
Biliary pain of right upper quadrant
What can gallstones impacting the common bile duct cause?
Obstruction of bile flow and cholestatic jaundice -> bacterial infections and right upper quadrant pain
What is cholangitis?
Inflammation (infection) of the bile duct
What can gallstones that block the duodena papilla cause?
Inappropriate activation of pancreatic juice and acute pancreatitis
What happens if the gallbladder is inflamed?
It will secrete mucus and eventually rupture