Session 7 - Liver And Pancreas Pathology Flashcards
What veins lead into the hepatic portal vein?
Superior mesenteric vein Inferior mesenteric vein Splenic vein Right gastric vein Left gastric vein
What arteries arise from the coeliac trunk?
Left gastric artery
Common hepatic artery
Splenic artery
Where does the break down of red blood cells occur?
Break down of red blood cells occurs extravascularly in macrophages in the spleen and liver.
How is bilirubin transported to the liver?
Bound to albumin (because bilirubin is hydrophobic) and transported in the blood stream.
What happens to the bilirubin once it reaches the liver?
It is conjugated with glucoronic acid by UDP glucuronyl transferase. Conjugated bilirubin is water soluble and is secreted by hepatocytes into bile canaliculi.
What molecules does the liver produce?
Albumin
Glycogen
Numerous coagulation factors
Also responsible to haematopoiesis in foetus (can be revived in adults if bone marrow is failing)
Give two examples of assay results which show decreased anabolism in the liver.
Hypoalbuminaemia - not enough albumin being produced.
Prolonged prothrombin time (INR) - not enough coagulation factors being produced.
Both reflect severe liver dysfunction
What molecules does the liver catabolise?
Drugs (cytochrome P450) Hormones Haemoglobin Poisons (cytochrome P450) Can take over the removal of red cells after a splenectomy
What is jaundice?
Yellowing of the skin and sclera due to build up of bilirubin in the blood and tissues.
What causes pre-hepatic jaundice?
Too much bilirubin, e.g. due to haemolytic anaemia
What causes intra-hepatic jaundice?
Failure of hepatocytes to conjugate and/or secrete most of the bilirubin presented to them. E.g. due to hepatitis, cirrhosis.
Cholestasis
What is cholestasis?
The reduction or stoppage of bile flow from the liver to the duodenum. Disorders of the liver, bile duct or pancreas can cause cholestasis.
What causes post-hepatic jaundice?
Failure of the biliary tree to convey conjugated bilirubin to the duodenum, e.g. biliary tree obstruction
Is conjugated bilirubin soluble?
Yes
What affect will high serum levels of conjugated bilirubin have on the urine?
Conjugated bilirubin is water soluble so if serum levels are high it will be excreted in the urine and turn the urine dark yellow (bilirubinuria).
The amount of bilirubin in urine can be measured with a dipstick.
Will excess urobilinogen noticeably colour the urine?
No, but it can be measured using a dipstick
In post-hepatic jaundice, the inability to secrete bile salts leads to what?
Pruritis (itching)
Describe what would be found in pre-hepatic jaundice.
Mild jaundice (lemon tinge)
Stools may be very dark
Urine colour normal
No pruritis
Raised serum bilirubin
Increased urinary urobiliogen
No conjugated bilirubin present in the urine
In the colon, urobilinogen is converted to what?
Urobilinogen is converted to stercobilin by bacteria in the colon. Stercobilin give stool a dark brown colour.
Describe what would be found in intra-hepatic jaundice.
Moderate jaundice
Stools normal
Urine dark
No pruritis usually
Raised serum bilirubin
Normal urinary urobiliogen
Conjugated bilirubin present in urine
Describe what would be found in post-hepatic jaundice.
Severe jaundice (green tinge)
Stools pale
Urine dark
Pruritis
Raised serum bilirubin
Decreased urinary urobiliogen
Conjugated bilirubin present in urine
What cells release alanine aminotransferase (ALT)?
Inflamed or damaged hepatocytes
Where is the enzyme alkaline phosphatase (Alk Phos) found?
Liver canaliculi
Bile ducts
Bone
What pathology can cause a raised Alk Phos?
Bone disease
Liver disease - particularly with cholestasis or biliary obstruction
When would a raised Alk Phos be normal?
When there is growing bone
The enzyme gamma-glutamyl transferase (Gamma GT) is present in what cells?
Bile duct cells and to a lesser extent in hepatocytes.
What can caused a raised Gamma GT level?
Bile duct obstruction
Also induced by alcohol - raised level may indicate alcoholism
What are the possible causes of a raised ALT?
Hepatitis:
- viral (hepatitis A, B, C, etc.)
- acute alcohol intake
- fatty liver disease
- drugs/toxins