The Liver: Anatomy and Function Flashcards
The two lobes of the liver are separated by which ligament?
Falciform ligament
Which lobe of the liver is bigger?
The right lobe
What are the functional units of the liver?
lobules (UK) or acinus (US)
How many sections could a surgeon separate a liver into?
8
Where does the liver receive blood from and in what proportions/
Portal vein - venous blood from gut (75%)
Hepatic artery - arterial blood (25%)
What is the venous drainage of the liver?
Blood enters, mixes in the sinusoids and drains via hepatic veins into the IVC near the right atrium
What is the functional significance of the arrangement of lobules and their blood supply?
a hepatocyte is never more than one cell away from blood supply
What are the smallest channels where blood can mix in the liver?
sinusoids
True or False?
- Liver cells are non-polarised cuboidal cells
- They have a low mitotic index
False - they are polarised polyhedral cells
True
What cell type makes up biliary epithelium?
polarised cuboidal or columnar epithelial cells
What is the function of the dense basement membrane in biliary epithelium?
prevent bile from coming into contact with the liver and damaging it
What is the function of squamous epithelial cells that line the hepatic vasculature?
protect the parenchyma from blood cells, bacteria and viruses
filter fluids
As well as normal endothelial functions e.g. ant-chromogenic, coagulation, leukocyte traffic, selective uptake, scavenging of waste products
What are Kupffer Cells?
Where are they found?
What are their functions?
Hepatic macrophages located within the sinusoids
Phagocytosis, regulation of microcirculation, removal of endotoxin
Can produce cytokines, present antigen and stimulate immune response
What are stellate cells?
By what name are they also known?
What is their function?
What is their role in fibrosis?
Also called Ito cells or lipocytes, perisinusoidal fat storing cells
Star shaped with multiple membrane processes
Can transform to a more fibroblast-like morphology in disease
In fibrosis, the make ECM
What are the 2 digestive functions of the liver
Carbohydrate and fat metabolism
Storage of vitamins and minerals
Where statins act and why?
They act in the liver to inhibit the enzyme that synthesises cholesterol
Which vitamins are fat soluble?
Vitamins A, D, E and K
What is the function of bile?
emulsification of fat
fat soluble vitamin uptake
excretion of some substances that cannot be cleared by kidneys (cholesterol, bilirubin)
What is the immune function of the liver?
Protection against pathogen arriving in the blood
Phagocytosis of old or dying cells
Innate immune functions
Indiction of tolerance
What are the detoxification and elimination functions of the liver?
urinary excretion (solubilisation of compounds)
biliary excretion (lipophilic compounds)
biotransformation of drugs
- redox reactions to make soluble (P450)
- conjugation to make water soluble
elimination of ammonia (by-product of protein metabolism)
What useful proteins does the liver produce?
Albumin Fibronectin and components of coagulation cascade Plasminogen Alpha-1 antitrypsin Transferrin Hepcidin
What are the 3 stages of liver damage?
Fatty liver - deposits of fat lead to liver enlargement
Liver fibrosis - scar tissue forms
Liver cirrhosis - growth of connective tissue destroys liver cells
What are the 3 complications of liver cirrhosis?
Renal failure
Oesophageal varices
Ascites
What are the main drivers of cirrhosis in the EU
viral infection
alcohol
metabolic syndrome
How does hepatitis cause damage?
Viruses selectively infect hepatocytes
Very strong immune response causes severe hepatitis
The immune system then kills the infected hepatocytes
Development of fibrosis and end stage liver failure
How does alcohol cause cirrhosis?
Toxic injury –> inflammatory response
