Accessory Organs - Gall Bladder Flashcards
Anatomical location?
Located in the right hypochondrial region.
It is an intra-peritoneal, pear-shaped structure that lies between the inferior aspects of the right and quadrate lobes of the liver.
What is function of the gall bladder?
1) Concentrate and store bile which is produced by the liver.
2) Bile is released in response to the cholecystokinin.
Anatomical relations?
The gall bladder is completely surrounded by peritoneum and in direct relation to the visceral surface of the liver.
It lies in the close proximity to the liver:
1) anteriorly and superiorly - inferior border of the liver and the anterior abdominal wall.
2) posteriorly - transverse colon and the proximal duodenum.
3) inferiorly - biliary tree and the remaining parts of the duodenum.
Anatomical structure?
The gallbladder has a storage capacity of 30-50ml and, in life, lies anterior to the first part of the duodenum. It is typically divided into three parts:
1) Fundus - the rounded, distal portion of the gall bladder. It projects into the inferior surface of the liver in the mid-clavicular line.
2) Body - the largest part of the gall bladder. It lies adjacent to the posteroinferior aspect of the liver, transverse colon, and the superior part of the duodenum.
3) Neck - the gallbladder becomes continuous with the cystic duct, leading into the biliary tree.
The neck contains a mucosal fold, known as Hartmann’s pouch. This is common location for gallstones to become dislodged, causing cholestasis.
What is the biliary tree?
The biliary tree is a series of GI ducts allowing newly synthesised bile from the liver to be concentrated and stored in the gall bladder (prior to release into the duodenum).
Bile is initially seceted into from hepatocytes and drains from both lobes into the right and left hepatic ducts. These ducts amalgamate to form the common hepatic duct, which runs along the hepatic vein.
As the common hepatic duct descends, it is joined by the cystic duct - which allows bile to flow in and out of the gallbladder for storage and release. At this point the common hepatic duct and the cystic duct combine to form the common bile duct.
The common bile duct descends and passes posteriorly to the first part of the duodenum and head of the pancreas. Here it is joined by the main pancreatic duct, forming the hepatopancreatic ampulla (ampulla of Vater) - which then empties into the duodenum via the major duodenal papilla. The papilla is regulated by a muscular valve, the sphincter of Oddi.
Vasculature
Arterial supply - cystic artery (a branch of the right hepatic artery, which is derived from the common hepatic artery, one of the major branches of the coeliac trunk).
Venous drainage (neck) - cystic veins -> portal vein
Venous drainage (fundus and body) - hepatic sinusoids.
Innervation?
Sympathetic and sensory - coeliac plexus
Parasympathetic - vagus nerve - stimulation produces gall bladder secretion (by relaxing the sphicter of Oddi). However, the majority of this response is mediated by cholescystokinin, as part of the gustatory response.
Lymph drainage?
Lymph drains into the cystic lymph nodes.
Clinical relevance: gallstones
Cholelithiasis, commonly known as gall stones, are small lumps of cholesterol, bile salts or a mixture of the two, which may form within the gallbladder. They are relatively common and often asymptomatic.
However, they may be associated with pain, jaundice and systemic upset (depending on the location of the gallstone, and the presence or absence of associated infection or inflammation).
Different terminologies are applied to distinguish between the pathologies:
1) Cholelithiasis - uncomplicated gall stones
2) Biliary colic - typically right upper quadrant pain following a fatty meanl as gallstones obstruct the cystic duct during contraction of the gall bladder. Not associated with systemic upset.
3) Cholecystitis - inflammation of the gall bladder. Pain is often associated with nausea, vomiting or fever.
4) Choledocholithiasis - gallstone within the common bile duct. Often causes deranged liver function tests.
5) Cholangitis - infection of the commmon bile duct often secondary to choledocholithiasis. Typically presents with right upper quadrant pain, fever and jaundice (Charcot’s Triad).
Once diagnosed, most symptomatic patients have surgical removal of the gall bladder (cholecystectomy); which is now often performed via laparascopic surgery during the acute phase or once recovery has taken place (often at 6 weeks). In the interim, patients are presribed analgesia and antibiotics when required.
