Biliary apparatus, gall bladder and gall stones Flashcards
Describe the path of the biliary apparatus?
Canaliculi -> Interlobar bile ducts -> septal bile ducts -> Intrahepatic bile ducts -> R/L hepatic duct -> Common hepatic duct -(meets with cystic duct)-> Common bile duct -> Ampulla of vater.
How much bile can the gall bladder hold?
30-50ml.
Where is the gallbladder located?
In the gall bladder fossa on inferior surface of the right liver lobe.
Name the parts of the gall bladder?
Fundus, body, neck, cystic duct.
What epithelia lines the gall bladder?
Columnar epithelia.
What is the function of the gallbladder?
Concentrates bile by absorbing water and salts.
Where is bile produced and how much?
around 400-800ml in hepatocytes
What stimulates bile secretion?
Vagal stimulation promotes gall bladder contraction.
CCK is released from duodenum in response to luminal fat. It also causes gall bladder contraction and relaxes the sphincter of oddi.
What closes the sphincter of oddi?
Sympathetic nerves
Vasoactive Intestinal Polypeptide (VIP) and Somatostatin.
How are bile salts recirculated?
95% in enterohepatic circulation.
Resorption occurs mainly in the ileum by active transport to portal circulation.
Synthesis in liver compensates for faecal loss.
Bile acids bound to albumin for transport to portal vein as it is hydrophoblic.
List risk factors for gall stones?
Female Fat Fertile Forty Fair (caucasian) Family history Low fibre/high fat diet Inflammatory bowel disease - as it often affects the ileum so can affect recirculation of bile acids.
Describe the pathogenesis of gallstones? Outline the 3 events that lead to stone formation.
- Cholesterol Supersaturation;
Cholesterol is usually solubilised by bile, but high levels of cholesterol can cause supersaturation.
This can also occur due to high oestrogen levels - obesity, pregnancy, oral contraceptive pill, liver disease (produces bile and metabolises oestrogen).
Can occur while bile acid levels are low e.g. following bowel resection or in active Crohns when enterohepatic circulation is ineffective. - Biliary Stasis;
Occurs during periods of fasting or starvation. Gallbladder does less work so more likely to precipitate and form stones. - Increased Bilirubin Secretion ;
Bilirubin is soluble in bile following conjugation. Pigmented stones can develop when there is increased RBC breakdown (sickle cell, malaria, post-chemo) or due to failure of hepatic conjugation (liver disease).
CAN BE THESE £ EVENTS OCCURRING TOGETHER OR SEPARATELY.
Describe 2 complications of bile stones?
- Biliary Colic.
Stone stuck in GB (usually neck/Hartmann’s pouch). The gall bladder contracts to try expel it. Usually onset is often after eating when gallbladder contracts.
Pain in right upper quadrant and back, often vomiting. No jaundice, fever and normal LFT’s. Often settles when stone moves back into body. If recurrent then Cholecystectomy. - Acute Cholecystits.
Stone impacted in gallbladder wall leading to oedema/inflammation and bacterial infection in wall.
Pain, nausea, vomiting, fever and abdominal tenderness.
Raised inflammatory markers, sometimes abnormal LFT’s or jaundice (if gallbladder compresses bile duct).
Treat with antibiotics, analgesia or elective cholestectomy.
List the symptoms of obstructive jaundice.
Pale stools and dark urine. Yellow sclerae. Itch. Features of chronic liver disease. Abdominal tenderness and palpable gallbladder.
What is choledocholithiasis?
What are the symptoms and treatment?
Migration of 1+ stone into the bile duct from gall bladder, commonly impacted above ampulla of vater where duct narrows.
Obstructive jaundice with pain, acute pancreatitis.
US/Magnetic Resonance Choleangiopancreaticography (MECP) or Endoscopic US.
Endoscopic Retrograde Choleangiopncreaticography (ERCP) to attempt stone removal via balloon catheter.
Cholecystectomy to prevent recurrence.
