Liver Stucture And Function Flashcards
List some of the functions of the liver
Amino acid, carbohydrates and lipid metabolism
Plasma protein and enzyme synthesise
Production of bile
Detoxification
Storage of proteins, glycogen, vitamins and metals
Production of some clotting factors
Immune functions
The hepatic artery delivers oxygenated blood to the liver. How much of the total liver blood supply does the hepatic artery comprise?
30-40%
The portal vein delivers deoxygenated blood directly from the GI tract, pancreas and spleen to the liver. How much of the total liver blood supply does the portal vein comprise?
60-70%
Which blood vessel drains the liver?
Hepatic vein
What vessels comprise the portal triad?
Branch of the hepatic artery
Branch of the portal vein
Branch of the bile duct
Why is the blood in the hepatic portal vein at a very low pressure?
Because it has already passed thorough the capillary beds in the GI tract
What is the name of the specialised capillaries which connect the hepatic artery and portal vein to the hepatic vein?
Liver sinusoids
What shape are the hepatic lobules?
Hexagonal
Where in the hepatic lobules does the branch of the hepatic vein lie?
In the centre of the lobule
Hepatocytes are arranged in plates. T/F?
True
On a histology slide how can you differentiate the three elements of the portal triad?
The epithelium of the bile duct has the thickest nuclei so stains a dark blue
The portal vein is larger and has thinner walls than the hepatic artery
At what surface of the hepatocyte does exchange of material between cell and blood supply occur?
Sinusoidal surface
What occurs at the canalicular surface of the hepatocyte?
Bile, produced by the hepatocyte, is drained into the canaliculi at this surface
The endothelium of the liver sinusoids is specialised to facilitate the exchange of material. In what ways does it differ from other endothelium?
It has fenestrations
It lacks a complete basement membrane so that there is less fibrous tissue to impede the exchange of material
In addition to hepatocytes, what other cells exist in the liver?
Kupffer cells (macrophages)
Perisinusoidal cells which store fat and fat soluble vitamins
Liver associated lymphocytes
Endothelial cells
What is the basement membrane of the liver sinusoids comprised of?
Parenchyma, reticulin
How is bile transported from hepatocyte to the common hepatic duct?
From the hepatocyte bile travels in canaliculi which become bile ductules and then bile ducts which run through the portal triad to eventually fuse to form the hepatic bile duct
Which protein transports unconjugated bilirubin from the breakdown of red blood cells to the liver?
Albumin
In what form is bilirubin secreted in faeces?
Stercobilinogen
In what form is bilirubin secreted in urine?
Urobilogen
Bilirubin is conjugated in the liver then secreted in bile and eventually leaves the body in…?
Mostly faeces but also some in urine
What are the four lobes of the liver?
Caudate
Quadrate
Right
Left
What is the name of the fibrous capsule which surrounds the liver?
Glissons capsule
What is the round ligament of the liver a remnant of?
The embryological umbilical vein
What functions are carried out particularly by the cells in zone one of the liver acini?
Citric acid cycle Fatty acid oxidation Gluconeogenesis Urea synthesis Production and excretion of bile
What functions are carried out particularly by cells in zone three of the liver acini?
Glycolysis
Glutamine synthesis
Xenobiotic metabolism
There is cross talking between the metabolic pathways of the liver. T/F?
True
How are carbohydrates stored in the liver?
As glycogen
What is the term for the release of carbohydrates by the liver?
Glycogenesis
What is gluconeogenesis?
The synthesis of glucose from other sources such as lactate, pyruvate, glycerol and alanine
Where in a hepatocyte does beta oxidation occur?
Mirochondria
What are the potential products of beta oxidation in hepatocytes?
Fatty acids Triglycerides Phospholipids Cholesterol Lipoproteins
What are fatty acids produced by the liver used for?
The production of ATP via the citric acid cycle
What is cholesterol, synthesised by the liver, used for?
Synthesis of membranes
Synthesis of hormones
Synthesis of other materials
What toxic compound is produced from normal amino acid metabolism and is converted to urea in the liver?
Ammonia
Why is hyperammonemia dangerous?
It can lead to brain damage
In phase one of detoxification toxic compounds are converted to hydroxylated or carboxylated non toxic compounds in the smooth endoplasmic reticulum of hepatocytes via which molecule?
Cytochrome 450
What happens in phase two of detoxification by hepatocytes?
Conjugation with glucuronic acid, acetyl or methyl radicals, glycine, taurine of sulphate
