Organisation and Function of the Liver Flashcards
State Courvoisier’s Law.
In the presence of an enlarged gallbladder that is non-tender and accompanied with mild jaundice, the cause is unlikely to be gallstones.
What is Calot’s triangle?
It is the triangular space that is dissected in a cholecystectomy to identify a window to safely expose the gallbladder. Demarcated by: common hepatic duct, cystic duct and the cystic artery
Where is the origin of the liver and biliary system in the gut tube?
Distal part of the foregut and the proximal midgut
What system is used to describe liver development?
Carnegie System - 23 stages - first 60 days of development
What is the septum transversum?
A thick mass of cranial mesenchyme that gives rise to parts of the thoracic diaphragm and ventral mesentery of the foregut - the septum transversum arises from the mesoderm
Around when does the liver bud become apparent?
29 days
What three structures form from the initial endodermal sprout?
Liver, Gallbladder and Ventral bud of the pancreas
When does the liver rotate to the right?
10 weeks
What proportion of the blood supply to the liver is via a) hepatic portal vein and b) hepatic artery proper?
Hepatic portal vein - 80%
Hepatic artery proper - 20%
The liver receives 25% of the cardiac output
Describe the Couinaud classification of the liver segments.
8 functionally independent segments - starting with 1 centrally and then going clockwise. Each segment can be resected without damaging the remaining segments.
State the five main cell types of the liver?
Hepatocytes Endothelial Cells (sinusoidal) Cholangiocytes Hepatic Stellate Cells Kupffer Cells
Where is bile produced?
Hepatocytes
And, to a lesser extent, in the cholangiocytes
Describe the morphological divisions of the liver.
Divided into lobules and portal tracts/triads
Describe the functional divisions of the liver.
Acini, blood flow, bile flow
What is a lobule?
An area of the liver that is at a HISTOLOGICAL scale. Hexagonal.
What are the three areas of a lobule?
Centrilobular
Midzonal
Periportal
What does the portal triad consist of?
Branch of the hepatic portal vein
Branch of the hepatic artery
Bile duct
Describe the path of the blood flow through a lobule.
The blood flows towards the central vein
What is that shape of an acinus and what are its three regions?
Diamond
Periportal
Transition zone
Pericentral
What are the roles of zone 1 and zone 3?
Zone 1 - gluconeogenesis, oxidation of fatty acids and cholesterol synthesis
Zone 3 - glycolysis, lipogenesis and P450 based drug detoxification
Describe the cytological features of a hepatocyte.
Hepatocytes are LARGE cells and they have a PALE + ROUNDED nucleus
Describe the cytological features of hepatic stellate cells and Kupffer cells.
They appear to be found in the sinusoids
They have a flat, dense nucleus
State four main functions of the liver.
Protein, Carbohydrate and Fat Metabolism
Detoxification
Describe the lipid metabolism function of hepatocytes.
Triglyceride metabolism - synthesis of fatty acids converted to triglycerides and lipoproteins for transport to the cells requiring energy
Digested triglyceride chylomicron remnants processed into lipoproteins
Bile acid production
What are the roles of hepatic stellate cells?
Vitamin A storage
Production of fibrous tissue (responsible for cirrhosis)
What are the roles of sinusoidal endothelial cells?
Fenestrated - allows lipids and other large molecule movement to and from hepatocytes
What are the roles of Kupffer cells?
Resident phagocytes
Secretion of cytokines that activate hepatic stellate cells
What bud are the biliary structures formed from?
Pars cystica
What does ERCP stand for?
Endoscopic retrograde cholangiopancreatography
On the ultrastructure of hepatocytes: how are the RER and Golgi Apparatus involved in protein metabolism?
• RER - needed for synthesis:
o Non-essential amino acids, clotting factors, albumin
• Golgi Apparatus - needed to pack for secretion
On the ultrastructure of hepatocytes: name three structures involved in carbohydrate metabolism. How can carbohydrates be metabolised?
- SER
- Mitochondria
- Cytoplasmic enzymes
• Needed for glycolysis, gluconeogenesis, glycogenolysis, glycogenesis
On the ultrastructure of hepatocytes: name three structures involved in lipid metabolism. How can lipids be metabolised?
- SER
- Peroxisomes
- Mitochondria
• Needed for triglyceride metabolism and bile acid production
On the ultrastructure of hepatocytes: name two structuress involved in detoxification. How does detoxification occur?
Detoxification
• Lysosomes
• SER
• Metabolise/modify/detoxify exogenous compounds
