Liver and pancreas Flashcards
What hormone causes bicarbonate release and from where when chyme enters the duodenum?
Secretin, causes pancreas to release bicarbonate
What effects does CCK release have when chyme enters the duodenum?
- Stimulates pancreas to release digestive enzymes - Causes gall bladder to contract and sphincter of odi to relax so bile can enter lumen
Other than CCK, what else stimulates enzyme and bicarbonate release form the pancreas?
Parasympathetic NS
What are the anatomical regions of the pancreas?
Tail, body, neck, head and uncinate (inferior to the head)
What components of pancreatic secretions are released by the acinar cells, and what’s released by the ductal cells?
Acinar= enzymes (amylases, lipases and proteases) Ductal cells= aqueous component and bicarbonate
What are zymogen granules?
These are capsules within the acinar cells which store the zymogens (enzyme precursors), until theyre ready to be released.
Describe the structure of the billary tree
Two common hepatic ducts drain into the cystic duct which drains into the gall bladder. The cystic duct is also the route of bile exit for the gall bladder, after the entry of the common hepatic duct it becomes the common bile duct. Once this joins with the pancreatic duct it becomes the hepatopancreatic duct or ampulla of vater.
What does bile consist of? (3)
bile acids, bile pigments and an alkaline solution
Where are bile acids, bile pigments and the alkine solution produced from?
Bile acids and pigments= hepatocytes
Alkaline solution= ductal cells
What does the gall bladder do to bile?
- Stores it
- Concentrates it
(Over concentration leads to gall stones)
What are bile salts?
Bile acids (eg cholic acid) conjugated with an amino acids (eg glycine)
Why are bile salts needed?
Because bile acids are not always soluable at duodenal pH, and if they weren’t theyd be useless.
It also gives them a hydrophillic and hydrophobic end, which enables them to emulsify fats
How are lipids digested and absorbed?
- Bile salts break down large globules of lipids into many small gobules so increased SA for fast digestion w/ lipases.
- Bile salts then create micelles w/ cholesterol and lipid breakdown products in
- Micelles transport digested lipids to enterocytes where they can diffuse in
- The lipid based molecules are built back up into TAG, phospholipids ect and packaged w/ apolipoproteins into chylomicrons which enter the lymphatics
Describe the recyling of bile salts
Bile salts not reabsorbed w/ the fats but remain in the lumen until they reach the terminal illeum where they are then reabsorbed and sent back to the liver
What is the functional area of a liver lobule called?
An acinus
Which area of a liver acinus is first affected by ischaemia?
the central zone (nearest the portal vein// zone 3) - worst blood supply as furthest from the portal triad (hepatic artery)
Which area of the liver acinus is first affected by toxins?
The peripheral zone (nr portal triad// zone 1)- this area has the best blood suppply as its nearest the hepatic artery. This does however mean its exposed to toxins first so more.
What is steatorrhoea and what causes it?
When there is fat in your poo- making it yellow, smelly and floating.
It is almost always due to pathology causing inadequate secretion of bile salts or pancreatic lipases than excess fat consumption.
What lies within the base falciform ligament?
the remenant of the fetal umbelical vein- which is also called the round ligament or ligamentum teres
What breaks down RBCs and where?
Macrophages in the spleen (and a bit in liver)
Describe the normal process of heame excretion after the RBC it came from is broken down
- haem is converted to bilirubin which binds to albumin in blood and goes to the liver
- In liver its conjugated w/ glucoronic acid by UDP glycyronyl transferase
- Conjugated bilirubin is water soluable so is secreted into bile canniculi
- Its released in bile, in the small intestine its converted into urobilinogen
- 10% of this is reabsorbed and travels to kidneys in blood, where its converted to urobilin and excreted (makes urine yellow)
- 90% is converted to stercobilin in the large bowel and is excreted in poo (makes poo dark brown)
What colour will urine go if there is excess conjugated bilirubin in the blood?
Dark yellow/ orange
How can excess urobilinogen be detected in the urine?
What pathology could cause increase in urobilinogen in urine?
No colour change but can be detected in urine?
haemolytic anaemia
Why do you get puritis w/ cholestasis?
bile not moving–> bile salts back up–> bile salts released into blood–> bile deposited in tissues–> causes itching
Give a cause of prehepatic jaundice?
haemolytic anaemia
What is the colour differance between prehepatic, intrahepatic and post hepatic jaundice?
pre= mild jaundice
Intra= moderate jaundice
Post= sevre jaundice (green tinge)
What will happen to the stool colour and urine colour in prehepatic jaundice?
Stool darker as more sterobilin excreted
Urine normal as conjugated bilirubin isnt forced into it (although there will be increased urobilin, but this can only be detected in dipstick)
Will there be puritis in pre, intra and/ or post hepatic jaundice?
In pre and intra no, as bile still able to leave
But there will be in post hepatic jaundice