16. Structure and Function of Liver Flashcards
(21 cards)
What vessels enter and leave the liver?
Enter:
hepatic portal vein
hepatic artery
Leave:
hepatic vein
What is the livers internal structure? stratified squamous lobular columnar stratified cuboidal
lobular
What is the portal triad?
hepatic artery
hepatic portal vein
bile duct
(present at each vertex of a lobule)
Where is bile produced my hepatocytes collected?
Bile canaliculi
What cell types are found in the liver?
- Hepatocytes
- Endothelial cells
- Kupffer cells (macrophages)
- Pit cells (natural killer cells)
- Hepatic stellate cells
What are the functions of the liver?
Factory:
carbohydrate, lipid, protein metabolism.
bile formation.
storage e.g. glycogen, vit A, minerals
Waste Management:
detoxification of xenobiotics.
removal of waste e.g. bilirubin breakdown, drugs, toxins.
Which of these functions does the liver not do?
- store vitamin A,D, K, B12, iron, copper
- nitrogen metabolism
- vitamin D activation
- lipid metabolism
- synthesis of albumin + clotting factors
- activate vitamin D
What are bile salts in the liver formed from?
Cholesterol
How does increasing dietary fibre and drugs like cholestyramine reduce cholesterol levels?
They bind to bile acid in the gut and prevent it recirculating.
Therefore more bile acid needs to be made from cholesterol, thus reducing blood cholesterol levels.
How to gall stones develop?
↑ cholesterol levels.
bile contains free cholesterol and bile salts, if too much cholesterol enters the bile, it cannot be solubilised by the bile salts and therefore cholesterol precipitates.
What is phase 1 of xenobiotic metabolism mainly performed by?
Cytochrome P450 enzymes (CYP)
Which of these is not a xenobiotic metabolism phase 2 reaction? oxidation conjugation glucuronidation sulphation hydroxylation reduction hydrolysis
oxidation
hydroxylation
hydrolysis
reduction
these are all phase 1 reactions.
What is a prodrug?
Why can they be useful?
Inactive (or less active) compound which is metabolised in the body to produce a therapeutically active form.
e.g tamoxifen
Improve absorption of the drug in the gut.
Allow for an alternative route of administration e.g. skin patch.
In a paracetamol overdose, the phase 2 pathway it is mainly metabolised by becomes overloaded, resulting in the build up of a toxic molecule which leads to liver failure.
What is this molecule?
NAPQI
N-acetyl-p-benzo-quinoneimine
Outline the steps in the metabolism of alcohol and the enzymes.
ethanol > acetylaldehyde
(alcohol dehydrogenase)
acetylaldehyde > acetate
(acetylealdehyde dehydrogenase)
Chronic alcohol use depletes cytochrome P450 enzyme levels.
True or False?
FALSE
chronic alcohol use induces the synthesis of MORE CYP enzymes, since they metabolise alcohol when levels are high.
Causes dosage issue when prescribing drugs.
Red blood cells are mainly phagocytosed by Kupffer cells in the liver.
True or False?
TRUE
The globin protein in haemoglobin is degraded.
How is the haem metabolised and removed?
Haem > biliverdin > bilirubin
bilirubin transported to liver hepatocytes attached to albumin.
Here it is conjugated and secreted into bile.
Further metabolised by bacteria in the gut > urobilinogen
urobilinogen > urobilin/stercobilin
Both are excreted.
What is prehepatic jaundice?
Jaundice caused by haemolytic anaemia e.g. sickle cell
RBC are being abnormally broken down
What is intrahepatic jaundice?
Jaundice caused by liver damage (infection, inflammation, cirrhosis) or is inherited (Gilbert’s syndrome).
What is extrahepatic jaundice?
Jaundice caused by a blockage (gallstones, pancreatic carcinoma)
