GUT- Bile, Gallbladder and Stones Flashcards
outline the process of bile flow
hepatocytes - bile canaliculi - terminal bile duct - hepatic ducts- common bile duct
what are the constituents of bile
bile acids, cholesterol, phospholipids, bile pigments (bilirubin / biliverdin), electrolytes, water
outline the process of bile secretion
bile acid dependent component - produced by hepatocytes which secrete bile acids, bile pigments and cholesterol into canaliculi
bile acid independent component- produced by ductal cells which secrete an alkaline solution stimulated by secretin
when is the secretion of bile greatest
after a meal
where is bile stored when it is not needed
the gallbladder
what function does the sphincter of oddi have
contracts during fasting
relaxes during and after meals
how is bile released from the gallbladder
during the cephalic phase impulses are emitted via the vagus nerve (ACh causing contraction, VIP/NO causing relaxation of sphincter of Oddi)
during the gastric phase impulses are generated via the vagus nerve
after eating CCK is released from the duodenum which stimulates gallbladder contraction and relaxes the sphincter of oddi allowing bile to flow into the duodenum
outline a basic overview of how the bile enters the duodenum
1- chyme enters the duodenum causing CCK release and secretin from duodenal endocrine cells
2- CCK and secretin enter the blood stream
3- CCK induces secretion of enzyme rich pancreatic juice- secretin causes secretion of bicarbonate rich pancreatic juice
4- bile salts stimulate liver to produce bile more rapidly
5- CCK causes gallbladder to contract and hepatopancreatic sphincter to relax
6- during cephalic and gastric phases, the vagal nerve causes weak contractions of gallbladder
is the incidence of gallstones higher in women or men
women (2:1 women to men)
what are the types of gallstones
cholesterol and calcium bilirubinate
outline factors involves in gallstone formation
bile stasis decreased amount of bile acids due to malabsorption / problems with production chronic infection - bacteria supersaturation of bile with cholesterol presence of nucleation factors
what is the pathogenicity of gallstones
small gallstones have easy passage
larger stones may lodge in the opening of the gallbladder or the duct from the pancreas
lodging at this point causes occlusion of bile and pancreatic secretions
what is jaundice
build up of bilirubin in the blood depositing at sites characterised by yellow pallor / eyes
how are gallstones diagnosed
ultrasound / CT
cholecystography - radioactive tracer to visualise gallbladder and ducts
ERCP (endoscope retrograde cholangiopancreatography)
high levels of CCK found in duodenal mucosa
what are the clinical features of gallstones
most are asymptomatic
if neck of cystic duct is occluded - biliary pain
if gallstones impact common bile duct = obstruction of juice can cause infection
gallbladder will secrete mucus if inflamed and may rupture
some people may present with pain in the scapula (due to convergence of nociceptors into somatic afferent pathways
