GI5 Hepatic function Flashcards
What is the largest organ in the body?
2) describe its development
3) describe its blood supply + what they transport
liver 2) Develops as an outgrowth from GI tract –accessory organ 3) Has “double” blood supply Hepatic artery – oxygenated blood Portal vein – nutrient rich blood
1) Descirbe anatomical structure of liver:
2) What are Kupffer cells:
Series of plates of hepatocytes that radiate from a central vein
Hepatocytes in contact with bloodstream on one side and bile canaliculi on the other
Between hepatocytes are vascular spaces (sinusoids)
2) phagocytic macrophages
What is present in the portal triad:
hepatic aa
hepatic portal vv (widest)
bile duct (thinnest)
What are the functions of the liver?
Detoxification of blood
Protein synthesis
Carbohydrate metabolism
Lipid metabolism
Secretion of bile
How does the liver detoxify the blood?
1.Excretion into the bile
2.Phagocytosis by Kupffer cells.
3.Chemical alteration of the molecules.
e.g. Ammonia is produced by deamination of amino acids in the liver.
Liver converts it into urea.
Excreted in urine.
How is ammonia produced in the liver from reactants in the blood?
glutamate undergoes oxidative deamination forming alpha-ketoglutarate and ammonia
What happens to ammonia in the liver
ammonias is reacted CO2 to form carbamoyl phosphate. Carbamoyl phosphate reacts ith ornithine to produce citrulline. Citrulline reacts with aspartate to form argininosuccinate. Ammonia also enters cycle here as aspartate can be formed in mitochondria by reacting it with with oxaloacetate to form aspartate which then enters cytosol. where it reacts with Citrulline to form Argininosuccinate then joins the urea cycle to form urea.
Strarting from argininosuccinate how is urea produced from the urea cycle?
1) argniosuccinate breaks into fumarate and arginine
2) arginine reacts with water to form UREA and ornithine
3) ornithine then reacts with carbamoyl phosphate to form citrulline
4) citrulline reacts with aspartate to form argininosuccinate
5) argininosuccinate breaks down into fumarate and arginine.
6) Arginine is hydrolysised (reacts with water ) to form ornithine and urea!
What is the formula of ammonia?
NH4 +
What proteins does the liver synthesise?
Albumin Globulin Fibrinogen Transferrin Plasma Lipoproteins (A,B,C,E,a)
What is the function of :
1) albumin
2) Fibrinogen
1) Constitutes 70% of the total plasma protein
Colloid osmotic pressure
Carrier protein
2) blood clotting
What is the function of :
1) transferrin
2) globulin
1) iron transport
2) Transport cholesterol and hormones
Produce blood clotting factors I, II, III, V, VII, IX, XI
Liver regulates blood glucose concentration by:
Glycogenesis - Too much glucose Synthesis of glycogen from glucose glycogen is stored in the liver Glycogenolysis - Glucose pools reduce Glycogen is hydrolyzed (digested) releasing glucose into the bloodstream Gluconeogenesis - If Glucose intake is low synthesis of glucose from protein or from lipid (via glycerol)
Where does gluconeogenesis occur?
liver and a bit in renal cortex, in the cytosol
What is a chylomicron ?
2) What is it made up of?
3) What is its function?
4) How is substances making up chylomicron release?
One of several classes of lipoproteins 2) 95 % triglycerides 5 % cholesterol Apoprotein B-48 3) Transport of fat from intestines to muscle and other energy utilizing tissues via lymph then blood stream 4) As it is circulating in the blood stream, they're recognised by lipoprotein lipases on the lining of blood vessels and other energy utilising tissues. = • Chylomicron remanents • High density lipoprotein- Cholesterol • FFA
What does lipases and cholesterolesterases break lipids down into? (what are lipids component parts)
monoglyceride, phosphophlipid, esterified free fatty acid (FFA) and cholesterol.
What regulates bile?
CCK (how much is released from the gall bladder)
secretin (amount that gets produced)
Describe how lipids are used by the body from the intestine lumen?
1) in intestinal cell via a mechanism cholesterol and monoglycerides, phospholipids and FFA enter
2)combine with Apoprotein B-48
and form a chylomicron and an esterified free fatty acid.
3)
What happens to the products of chylomicron after being broken down by lipoprotein lipases:
1) Chylomicron remanents
2) High density lipoprotein- Cholesterol (HDL-C)
3) free fatty acids (FFA)
4) Glycerol
1&2)are taken to liver via hepatic portal vein and taken up by hepatocytes
3) stored in adipose cells as fat or used for energy in cells.
What happens to cholesterol in hepatocytes?
be released as low density lipoprotein cholesterol back into the blood stream
What happens to the chylomicron remnants in hepatocytes?
The chylomicron remnants will be broken down into cholesterol, free fatty acids and lipoproteins.
used to make bile salts. stored in gall bladder and released when we eat more fat.
How much bile is secreted per day by hepatocytes?
2) what colour is it?
3) what is bilirubin a derivative of?
4) How is conjugated bilirubin formed?
5) where is conjugated bilirubin stored?
250-1500ml of bile/day,
2) yellow
3) derivative of the heme groups (without iron) from haemoglobin.
4) Free bilirubin combines with glucuronic acid and forms conjugated bilirubin.
5) gall bladder
What happens to conjugated bilirubin when it enters the intestine?
2) What happens to bile acids when they enter the ileum?
1) converted by bacteria in the intestine to urobilogen.
- Urobilogen is absorbed by intestine and enters the hepatic vein
- Recycled, or filtered by kidneys and excreted in urine if we have too much
2) 95% are reabsorbed
1) What is bilirubin bound to in the liver?
2) What is it bound to in the gall bladder?
3) What is another word for bilirubin conjugated to glucoronic acid?
1) for glutathione, bilirubin is generally bound to glutathione in the liver – until it forms bile (it likes to be bound to protein), so is stored this way
2) In the liver, bilirubin is conjugated with glucuronic acid by the enzyme glucuronyltransferase, making it soluble in water:
3)glucornoid???
could be wrong blaheaiguh
