Liver bilirubin, haem, jaundice and pancreas Flashcards
Bile pigments are formed from what? Predominant pigment?
The haem portion of haemoglobin when old/ damaged erythrocytes are broken down in spleen and liver.
Bilirubin- extracted from blood by hepatocytes and actively secreted into bile, is yellow.
Erythrocytes broken down by what? Occurs where?
By macrophages
In spleen and bone marrow but also in Kupffer cells of liver
Globin from haemoglobin is broken down into what? Haem broken down into what by what enzyme? Fe2+ shuttled to bone marrow how?
Amino acids- make new erythrocytes in bone marrow
Hemoxygenase into biliverdin and Fe2+ and CO
Bound to transferrin- incorporated into new erythrocytes
Biliverdin is reduced by what enzyme? How is this excreted?
Biliverdin reductase into unconjugated bilirubin.
Toxic so is bound to albumin and transported to the liver- undergoes glucorindation by UDP glucuronyl transferase which converts it into conjugated bilirubin.
Conjugated bilirubin goes where after being formed? Travels to the small intestine until it reaches where? What reaction happens here?
Dissolves in bile and stored in gallbladder and enters duodenum
The ileum/ beginning of colon- hydrolysis reaction where intestinal bacteria reduces it to form urobilinogen.
% of urobilinogen is reabsorbed into the blood? Urobilinogen is oxidised to what?
10% is reabsorbed- lipid soluble, binds to albumin and is transported back to the liver.
Urobilin.
What happens to urobilin when it reaches the liver? What happens to other 90% of urobilinogen? Stercobilin responsible for colour of what?
It is either recycled into bile/ transported into the kidneys where it is excreted in urine.
It is oxidised by a different type of intestinal bacteria to form stercobilin.
Brown colour of faeces.
Jaundice caused by high serum bilirubin level above what value? 3 types of jaundice?
50 micromol/ L.
Pre-hepatic, hepatic/ intrahepatic and post-hepatic/ obstructive.
Pre-hepatic jaundice increases levels of what? Due to what? Without what in the urine? Other symptoms?
Unconjugated bilirubin.
Increased breakdown of erythrocytes.
Without excess bilirubin in the urine- stools brown and urine normal.
Yellow skin and enlarged spleen.
Pre-hepatic jaundice caused by what?
Malaria, sickle cell anaemia, thalassaemia, physiological jaundice of the newborn.
Hepatic jaundice caused by what?
Hepatocellular swelling- parenchymal liver disease/ abnormalities at cellular level/ infection/ exposure to harmful substance.
Impaired cellular uptake/ defective conjugation/ abnormal secretion of bilirubin by the hepatocytes– increase in serum unconjugated and conjugated bilirubin
Symptoms of hepatic jaundice? Causes?
Decreased urobilinogen, dark urine, pale/ normal stools, enlarged spleen, yellow skin.
Viral hepatitis, drugs, alcohol hepatitis, cirrhosis, jaundice of newborn.
When does post-hepatic jaundice happen? What is elevated?
When the biliary system is damaged/ inflamed/ obstructed.
Elevated serum conjugated bilirubin.
Symptoms of post-hepatic jaundice? Causes?
Dark urine, pale stools, normal levels of unconjugated bilirubin, decreased urobilinogen, no enlarged spleen, yellow skin.
Gallstones, pancreatic cancer, gallbladder cancer, bile duct cancer, pancreatitis.
What happens in Gilbert syndrome?
Shortage of UDP glycerol transferase, small amounts of conjugation- normal conjugated bilirubin level but raised unconjugated bilirubin level.
When can gallstones form? Results of different sizes?
When concentration of cholesterol in bile becomes high in relation to concentrations of phospholipid and bile salts.
Small= pass into intestines, large= lodged in gallbladder opening (painful contractile spasms,)/ lodged in common bile duct- less bile into intestine.
Less bile into intestines can lead to what?
Decrease in fat digestion and absorption and impaired absorption of fat-soluble vitamins A,D,K and E– clotting issues and calcium malabsorption.
Name for fat appearing in faeces? How is diarrhoea and nutrient loss caused?
Steatorrhea.
Bacteria in colon convert some into fatty acid derivatives altering salt and water movements.
Is pancreas retro/ intraperitoneal? Tail is attached to where? Inflammation of head can cause what?
Retroperitoneal apart from tail.
To the spleen
Block bile duct– post-hepatic/ obstructive jaundice.
Which artery runs through the head of the pancreas? Venous drainage achieved how?
Superior mesenteric artery.
By splenic vein- joins superior mesenteric vein– portal vein.
Exocrine pancreas excretes what from where? Secretions go into where?
Bicarbonate and digestive enzymes from acinar tissue of pancreas.
pancreatic duct which joins common bile duct just before entering duodenum at ampulla of Vater.
What does the sphincter of Oddi do? Where does the accessory pancreatic duct usually emerges where?
Separate bundle of circular muscle which regulates flow into the duodenum and prevents mixing of bile and pancreatic juice within pancreatic duct.
Above the ampulla of Vater.
Where is HCO3- secreted from in the pancreas? What is it used for?
Duct cells lining the ducts
Protects the duodenal mucosa from gastric acid and buffers material to pH suitable for enzymes
What hormone is released due to acid in the duodenum to stimulate HCO3- secretion? Also potentiates action of what hormone? Secretin also does what?
Secretin- HCO3- comes from pancreas and liver
CCK- stimulates enzyme secretion
Inhibits acid secretion and gastric motility in the stomach
