Pancreas and Liver Flashcards
When a drop in duodenal pH is detected - as chyme enters - what is released by cells in the duodenum? What effect does the secretion of this substance have?
Secretin is release which stimulates the release of bicarbonate rich secretions from the pancreas which help raise the pH of duodenal contents
What structures enter and exit via the porta hepatis?
Hepatic portal vein, hepatic arteries and hepatic bile ducts
In the porta hepatis which structures are transferring substances into the liver and which structure out?
In - hepatic portal vein and hepatic arteries
Out - hepatic bile ducts
The hepatic veins drain the liver into…
Inferior Vena Cava (IVC)
When is the common bile duct formed?
When the common hepatic duct joins the cystic duct
Where does the pancreas connect to the GIT to transfer its exocrine secretions?
2nd part of the duodenum (descending portion)
What controls the opening of the pancreatic and common bile ducts into the duodenum?
muscular sphincter of Oddi
How would you describe the properties of chyme as it leaves the stomach?
Hypertonic
Acidic
What is chyme?
A semi-fluid mixture of partially digested food
Why is chyme hypertonic?
Walls of the stomach are not permeable to water. Normally water would flow into an area of high solute like the lumen of the stomach to dilute it
What is the primary function of bile?
To facilitate lipid digestion - helps disperse lipids in solution, creating a larger surface area for lipase to work on
What are bile acids converted to?
Bile salts
What is the name of the functional unit of the liver?
the acinus
The functional unit of the liver, the acinus, is divided into 3 zones. Zone 3 is more at risk of ischaemic damage than zone 1. Why?
Greater distance from where blood (arterial and venous) enters the acinus at the portal triad. If there is a sustained drop in blood entering the acinus then zone 3 cells will face greater necrosis from ischaemia than zone 1 cells
Which cell types make up zones 1,2 and 3 of the liver acinus?
Hepatocytes - the main cell of the liver
When fatty acids and amino acids are detected in the duodenum, what GI hormone is released that stimulates the pancreas to produce digestive enzymes?
Cholecystokinin (CCK)
What is the role of CCK in digestion?
It is secreted in response to the presence of amino acids and fatty acids in the duodenum.
It stimulates the pancreas to secrete enzymes, contraction of the gallbladder and relaxation of the sphincter of Oddi
What stimulates the secretion of secretin?
Drop in duodenal pH
What is the role of secretin in digestion?
It is secreted in response to a drop in duodenal pH and stimulates the release of a bicarbonate rich pancreatic secretion
What is the structural unit of the liver called?
Lobule
What is the name of the structure in the centre of a lobule?
Central vein
What is the name of the structure at the vertices of a lobule?
Portal triads
How is the structure of the liver lobule formed?
Invaginations of the liver capsule
What abdominal ligament connects the liver to the anterior abdominal wall?
Falciform ligament
From where is the falciform ligament derived?
Ventral mesogastrium
What abdominal ligaments connects the liver to the diaphragm?
Coronary ligaments and triangular ligaments (left TL connects left lobe, right TL right lobe)
What does the free border of the falciform ligament contain?
Ligamentum teres - the remenant of the fetal umbilical vein, patent until a few months after birth
What causes caput medusae?
In severe portal hypertension, the small paraumbilical veins that remain in the round ligament of the liver (ligamentum teres) form porto-systemic anastomes around the umbilicus where the ligmentum teres inserts. Swelling of these veins are distinctive and look like Medusa’s head
What is the role of the acinar cells in the exocrine pancreas?
Produce digestive enzymes (amylases, proteases and lipases)
What is the role of the centroacinar and ductal cells of the exocrine pancreas?
Secrete the aqueous component of pancreatic exocrine secretions
What is the role of ductal cells in the exocrine pancreas?
Secrete HCO3- in exchange for Cl-
The portal vein is commonly formed when which two large veins unite?
Superior mesenteric vein and splenic vein
When does the left gastric vein drain into the portal vein?
After the splenic and superior mesenteric vein have joined together to form the portal vein.
In which clinical condition is the left splenic vein important?
Portal hypertension - it is important in the formation of oesophageal varices
What provides the liver with its greatest structural support in the abdominal cavity?
The inferior vena cava provides the greatest structural support (maintaining its position) via its connection through the hepatic veins which drain blood from the liver to the IVC
Why does urine have a dark colour in post hepatic jaundice?
Presence of bilirubin in urine - if bilirubin cannot be excreted into the gut or has reduced secretion into the gut (post-hepatic jaundice) then it will be excreted in urine (bilirubin is conjugated by the liver at this stage and therefore water soluble). Bilirubin is a pigment and will give urine a dark colour
What happens to urobilinogen levels in urine in post-hepatice (obstructive) jaundice?
Urobilinogen levels will be decreased because urobilinogen is a product of bilirubin reduction in the gut. If bilirubin cannot make it to the gut then urobilinogen cannot be formed
What happens to stercobilinogen levels in faeces in post-hepatic (obstructive) jaundice?
Stercobilinogen levels will be decreased in faeces because stercobilinogen is a product of urobilinogen reduction in the gut (and gives faeces its brown colour). It does NOT get excreted in urine. In post-hepatic jaundice there is less stercobilin formed therefore faeces are pale in colour.
What types of jaundice gives you unconjugated hyperbilirubinaemia?
Pre-hepatic, therefore any process that gives you excess red blood cell breakdown will give you it.
Pre-hepatic jaundice occurs because when too much bilirubin is released for the liver to conjugate.
What is bilirubin a breakdown product of?
Haem, released from the breakdown of red blood cells
What is bilirubin conjugated with in the liver to make it watersoluble?
Glucuronic acid
Conjugated bilirubin is excreted in bile to the intestines. What happens in the intestines to convert it to urobilinogen?
Colonic bacteria deconjugate it
How is urobilinogen present in urine?
Some is reabsorbed from the colon and then excreted in urine
How is stercobilinogen formed?
The urobilinogen that is not aborbed in the gut is converted to stercobilinogen (the brown colour of faeces)
The common hepatic duct form from the union of which two bile ducts?
Left hepatic and right hepatic ducts
What is the name of the bile duct which drains bile from the gallbladder?
Cystic duct
What is the name of the bile duct which drains into the second part of the duodenum?
Common bile duct
Which liver function test blood test results when raised would most SPECIFICALLY indicate hepatocyte damage?
Alanine transaminase (ALT)
What blood test result becomes raised in biliary obstruction and bone disease?
Alanine transaminase (ALT)
Why is raised aspartate aminotransferase (AST) not specific to hepatocyte damage?
It is raised in liver damage but is also present in reasonable quantities in cardiac and skeletal muscle
When are raised conjugated bilirubin levels seen?
They are seen more in biliary obstruction that occurs after conjugation has occurred (common bile duct blockage etc.)
What is a common cause of conjugated hyperbilirubinaemia?
Gallstone in the common bile duct
What is epigastric pain following a meal consistent with?
Gallstones
What raised blood test would reliably indicate that a gallstone is stuck in the common bile duct?
conjugated bilirubin levels
ALP tends to rise in biliary obstruction too but is not as specific an indicator as raised bilirubin levels
In alcoholic liver disease what liver function test (LFT) is often dramatically raised?
Serum Gamma-gltamyl transpeptidase (GGT) can be raised in all diseases of the liver, biliary system and pancreas but is markedly raised in alcoholic liver disease
What is biliary colic?
Pain when gallbladder contracts due to a gallstone transiently lodged in cystic duct
What can happen if a gallstone stays lodged in the cystic duct?
Acute cholecystitis - inflammation of the gallbladder
What does the term cholelithiasis mean?
Presence of gallstones in the gallbladder/ billiary tree
What are the symptoms of gallstones?
Having gallstones does not automatically mean that you will develop symptoms, many people are asymptomatic. Biliary colic, jaundice, right hypochondriac pain can all be symptoms of gallstones
A 48 year old man with a background of chronic alcohol dependence sees his GP for advice. He has had multiple episodes of intermittent severe abdominal pain radiating to his back which are becoming more frequent. He also describes umplanned weight loss of 8kg over 6 months, and loose stools that float in the toilet pan. His BMI is 19kg/m2 and urinalysis shows glucose ++. What condition underlies all the symptoms described?
Chronic pancreatitis
Weight loss caused by malaabsorption of food
Diabetes can develop if pancreatic beta cells are damaged
