Anatomy of the Biliary Tract, Pancreas and Spleen Flashcards
What is the biliary tree?
- system of vessels
- includes gall bladder, pancrease and spleen
Why are the gall bladder, pancrease and spleen characterised as accessory organs of the GIT?
- they are not involved directly with digestion
Do the gall bladder, pancrease and spleen arise from the foregut, mid or hindgut?
- foregut
What is the main blood supply to the biliary tree that originates from the abdominal artery?
- coeliac artery, also known as the coeliac axis
What are the 3 main functions of the gall bladder?
1 - Store and concentrate bile
2 - Selectively absorb bile salts
3 - Excrete cholesterol and mucous
What are the 3 main components of bile?
1 - bile salts
2 - cholesterol
3 - mucus
Bile includes bile salts, cholesterol and mucus at roughly equal concentrations. What can happen if these concentrations are slighlty off?
- crystalisation of one of the components can occur
- the foundation of gall bladder stones
Bile is made by hepatocytes in the liver, travels down the canniculi into the bile ducts at the portal triad. How does this bile then make its way to the gall bladder?
- bile ducts from left and right lobes of the liver merge forming left and right hepatic ducts
- these leave the liver forming the common hepatic duct
- this then merges with the cystic duct
What are the 3 parts of the gallbladder?
1 - fundus
2 - body
3 - neck (also known as Hartmans pouch)
Which duct attaches the gall bladder to the common bile duct?
- cystic duct
Where does the common bile duct run and join below the gallbladder?
- runs behind the duodenum
- merges with the main pancreatic duct
What is the ampulla of vater and what is its importance?
- where the common bile and pancreatic duct merge
- drains into the duodenum, called duodenum papilla
What are the antierior relations of the gallbladder close to?
- visceral surface of the liver
- anterior abdominal wall
- at the level of the the ninth right costal cartilage
What are the posterior relations of the fundus of the gallbladder close to?
= neck = the lesser omentum
= body = first and second parts of the duodenum
What are the inferior relations of the gallbladder close to?
- transverse colon
What is the main arterial blood supply to the gallbladder, and where does this originate from?
- cystic artery
- normally originates from right hepatic artery
- hepatic artery comes from common hepatic artery
How is the blood from the gallbladder drained
- through small blood vessels directly into the liver
- attachment to the liver allows this
What lies within the intrahepatic (inside the liver) bilary tree?
- bile canaliculi unite to form segmental bile ducts
- segmental bile ducts drain each liver segments
- segmental ducts combine to form sectoral ducts in right lobe
- left lobe remains as segmental ducts
What lies within the extrahepatic (outside the liver) bilary tree?
- right and left hepatic ducts
Why is it important to understand what lies within the intra and extrahepatic bilary tree?
- liver function tests can detect changes in intra and extrahepatic bilary tree
The common bile duct is around 7.5cm long and can be divided into three sections, the upper, middle and lower. Where is the upper third located?
- free edge of lesser omentum
- portal vein behind the common hepatic artery to left
The common bile duct is around 7.5cm long and can be divided into three sections, the upper, middle and lower. Where is the middle third located?
- behind first part of duodenum
The common bile duct is around 7.5cm long and can be divided into three sections, the upper, middle and lower. Where is the lower third located?
- posterior aspect of head of pancreas
- joins pancreatic duct at Ampulla of Vater into 2nd part of duodenum
- sphincter of Oddi controls bile flow rate
What is Endoscopic Retrograde Cholangio Pancreatography (ERCP)?
- endoscopic = insertion of tube into throat
- retrograde = moving backwards
- cholangio = bile vessel
- pancreatography = radiography of the pancrease
What rare the 2 main functions of the pancrease?
1 - exocrine secretion
- secretion of digestive enzymes via the pancreatic duct
2 - endocrine secretion
- secretes hormones such as insulin and glucagon
- islets of langerhans
What cells in the pancrease create pancreatic enzymes that get secreted into the GIT and where do they collect in the pancrease?
- acinar cells
- collect in small ducts
The acinar cells in the pancrease create pancreatic enzymes that collect in small ducts, before joining which duct?
- the main duct called Duct of Wirsung
Once collected into the main duct of the pancrease, also known as the Wirsung duct, how do these enzymes get secreted into the GIT?
- the Wirsung duct meets the common bile duct at the ampulla of Vater
- sphincter of oddi controls flow rate into duodenum
- ampulla of Vater empties into the duodenum at the major duodenal papilla
The head of the pancrease is drained by its own duct, which then goes onto join the Duct of Wirsung. What is the name of this duct?
- santorini or accessory duct
What are the 4 regions of the pancrease called?
- head
- neck
- body
- tail
Where does the head of the pancrease lie?
- fills loop of duodenum
- anteriorly to the inferior vena cava
The head of the pancrease can be split into 2, what is the posterior section of this called?
- Uncinate Process
What is the main bony structure that lies either side of the head and tail of the pancrease?
- vertebral column
What large blood vessels lie posteriorly to the neck and body of the pancrease?
- Inferior Vena Cava and the Abdominal Aorta
- crosses the origin of the Superior Mesenteric Artery
Which artery runs along the upper border of the pancrease?
- splenic artery passes along upper border
Which vein lies posteriorly to the neck and body of the pancrease and joins the superior mesenteric vein to form the portal vein?
- splenic vein
What organ does the tail of the pancrease overlie?
- the left kidney
- the tip touches the splenic hilum
What are the main blood vessels supplying the pancrease?
- arteries = splenic and pancreatico-duodenal
- veins = small veins drain into splenic vein
How is the pancreas inervated sympathetically and parasympathetically?
- sympathetic = coeliac ganglia
- parasympathetic = vagus
Which ribs can the spleen be located under?
- 9th to 11th
The spleen contains red and white pulp, what is the function of each of these?
- red pulp = blood filled sinuses
- white pulp = lymphatic tissue (think white blood cells)
Where can the spleen be located in relation to the left kidney?
- anterior to the left kidney
Where can the spleen be located in relation to the colon?
- at the point of reflection between transverse and descending colon
What are the main blood vessels supplying the spleen?
- splenic artery
- splenic vein that then joins the Superior Mesenteric Vein to form the Portal Vein
Endoscopic retrograde cholangio pancreatography (ERCP) can be used to investigate common bile duct stones. What can happen to the common bile duct and how can this be treated?
- common bile duct dilates
- stones move from cystic duct to common bile duct
- get lodged at narrowing locations, commonly at sphincter of oddi
- surgery divides the sphincter of oddi and retrieves the stone
In addition to common bile duct stones, what other problem in the pancrease can cause jaundice?
- pancreatic cancer
- blocks the biliary tree
What is a Splenomegaly?
- enlarged spleen
- becomes enlarged due to infection or pathophysiology
The common hepatic duct runs behind the duodenum and merges with the main pancreatic ducts. What is the name where these merge and then enter the duodenum?
- ampulla of vatar
The common hepatic duct runs behind the duodenum and merges with the main pancreatic ducts. This enters the duodenum at the ampulla of vater (sounds like darth vadar). What is the name of the sphincter that controls entry into the duodenum?
- sphincter of oddi
