What is the gross anatomy of the liver - anteriorally?
2 lobes - right (60%), left (40%) Gall bladder just below right lobe Falciform ligament is in between RL and LL, holding them both together
What is the Carnegie Stage system?
23 stages providing a unified developmental chronology, covering only day 0-60 of development
How does the liver receive blood?
Dual blood supply - hepatic artery (20), and hepatic portal vein (80 - venous) All drained into inferior vena cava
What is the purpose of blood delivered to the liver by HPV and HA?
HA - deliver O2 and nutrients HPV - brings blood from gut so that it is filtered before entering the circulation
What is the couinaud classification?
8 functionally independent segments - each has a branch of HPV, HA and HV, so each segment is drain and receives its own blood Each segment can be resected without affecting any other segment
What are the different cell types in the liver?
Hepatic cells, endothelial cells, cholangiocytes, kupffer cells and hepatic stellate cells
What are Hepatocytes and non-parenchymal cells?
Kupffer or hepatic stellate cells are flattened dense cell nuclei that appear to be in sinusoids Hepatocytes are large cells with pale rounded nuclei
What are Hepatic stellate cells and what do they do?
Vitamin A storage, activation means ECM production (fibrogenesis) BUT not really active in healthy liver, but they are very important in causing liver cirrhosis as normal healthy tissue has collagen and become fibrotic
What are Sinusoidal endothelial cells?
Fenestrated - allows lipids and other molecules movement to and from hepatocytes
What are Kupffer cells?
Phagocytosis - RBC breakdown Secretion of cytokines - promote hepatic stellate cells activation causing proliferation, contraction and fibrogenesis
What are the micro-anatomy structures?
Morphological - lobules, portal tracts/triads Functional - acinis, blood flow, bile flow
What is the Surface anatomy of the liver?
Liver is just below diaphragm, 2nd largest organ after skin Largely right sided, but apex of liver is on rhs
What are Acinis?
Unit of hepatocytes divided into 3 zones dependent on proximity to arterial blood supply Functional unit which is less clearly identifed
Hepatocytes in which zones are more susceptible to ischemia and viral hepatitis?
Ischemia - zone 3 Viral hepatitis - zone 1
Where is bile produced and where does it flow to?
Produced by hepatocytes and flows in opposite direction to blood, along canaliculus to bile duct - then towards gall bladder and intestine
What is the function of hepatiocytes?
Protein metabolism, carb metabolism, lipid met, detoxification - all of which needs energy from mitchondria
How is protein synthesis and metabolism carried out in the hepatocyte?
RER does synthesis, GA packages for secretion, and deamination of amino acids (amino group to urea cycle and carbon skeleton is reused)
How and where is carbohydrate metabolism carried out in the hepatocyte?
Glycolysis, gluconeogenesis, glycogenolysis, gluconeogenesis Uses SER, mitochondria, cytoplasmic enzymes
How and where is lipid metabolism carried out in the hepatocyte?
Triglyceride metabolism - FA converted to TG and lipoproteins for transport to energy requiring cells; digested TG chylomicron remnants processed into lipoproteins Bile acid production Using SER, peroxisomes and mitochondria
How and where does detoxification occur in hepatocytes?
Metabolise, modify/detoxify exogenous compounds Using Lysosomes and SER
Give an example of a transamination example
Alanine + alpha oxoglutaric acid --> glutamic acid and Pyruvic acid
How does deamiation take place in situ (liver and muscle)?
Muscle releases alanine into blood, taken to liver where it has the amine group removed, leaving the carbon skeleton (which can then be entered into TCA to make glucose) The amine group is very toxic (NH3) so needs to be transformed into urea, which is water soluble, metabolically inert and non-toxic. Urea is then excreted in urine
What is the role of the liver in fat metabolism?
Fat is main energy store in body, stored in adipose and liver tissue - liver can convert excess glucose and a.a. to fat for storage Metabolise fat for energy source, converting FA to acetyl CoA and can turn acetyl CoA to acetoacetate for transport in blood Synthesises cholesterol, lipoproteins, phospholipids
Why is liver disease important?
It affects 2 million people in the UK and incidence is rising 1 in 50 of all deaths
What is the gross anatomy of the liver posteriorly?
4 lobes: Left, Right, Caudate and Quadrate (next to gallbladder)
What are the 2 types of layers of cells that make up the liver in the embryo?
Endoderm (parenchymal tissue), mesoderm (connective tissue)
What is similar about the liver and biliary system development?
They both share a common origin with the ventral part of the pancreas at the distal foregut/proximal midgut
What are the stages 11, 12, 13, 14, 18 and 18-23 in the carnegie stage?
What are the most important carnegie stages in the liver?
Stage 11, day 29 is most important - liver bud develops, and fuses (kind of) with mesoderm Structure from day 40-60 begins to develop By 8 weeks it starts to migrate By 10 weeks moved completely to RHS
From what does the septum transversum arise in embryology?
The mesoderm - gives rise to parts of thoracic diaphragm and ventral mesentry of foregut in developed human