Liver Flashcards
What are the four lobes of the liver?
left, right, caudate and quadrate
Where is a lap cholecyetectomy done?
In gallbladder in junction of segments 4 and 5 - safe removal of gallbladder from Calot’s triangle.
Where is Calot’s triangle
Triangle bound by the cystic duct, bile duct and cytic artery.
What supplies blood to the liver?
20% arterial blood from left and right hepatic arteries
80% from venous blood from hepatic portal vein
Where does the blood from the liver drain to and via what?
Drains to the inferior vena cava via the hepatic vein
How much of the resting cardiac output goes to liver?
25%
What are hepatic lobules
roughly hexagonal structural with a portal triad at each corner to link with adjacent lobules and a central vein in the middle to collect blood from hepatic sinusoids to return to venous system (w/ rows of hepatocytes, each with a sinusoid-facing and caniculi-facing side)
What does a branch of the hepatic portal vein contain?
mixed venous blood from GI organs and spllen, rich in raw nutrients, toxins and waste products - hepatocytes process nutrients and detoxify blood
What shape is the acinus?
elliptical or diamond shaped and divided into 3 zones
What are found around the edges of adjoining lobules?
Portal tracts
What are portal triads composed of?
An arteriole
A branch of the portal vein
A bile duct
Where does blood flow in the liver?
Deoxygenated blood nutrient rich from the portal vein and oxygenated blood from hepatic artery flow towards central vein
What functions does the liver have a key role in?
- digestion
- biosynthesis
- energy metabolism
- degradation
- detoxification
What are the 5 cell types in the liver?
Hepatocytes Endothelial cells Cholangiocytes Kupffer cells Hepatic stellate cells
What do hepatocytes look like?
Large cells with pale and rounded nuclei
What do kupffer cells or hepatic stellate cells look like?
Flattened dense cell nuclei that appear to be in the sinusoids
What are acinus
A cluster of cells - unit of hepatocytes divided into zones depending on proximity to arterial blood supply
What are the different zones in the acinus called?
1) periportal
2) transition zone
3) pericentral
Which zone of the acinus is the least susceptible to ischaemic injury and why? However it is most susceptible to what?
Zone 1, closest to entering vascular supply so gets most oxygenated blood, but most susceptible to viral hepatitis or hemosderin deposition in haemachromatosis
What is periportal zone 1 involved in?
Gluconeogenesis
oxidation of fatty acids
cholesterol synthesis
What is acinus zone 3 involved in?
glycolysis
lipogenesis
p450 based drug detoxification
Where is the terminal acinus found? And where is hepati acinus found?
Terminal - centred on portal tract
Hepati - centred on line connecting two portal triads
What produces bile and where does it flow?
Bile is produced by hepatocytes, and flows along canaliculus to bile duct
Liver function in metabolism of carbohydrates?
Control blood glucose as XS glucose taken up by tissues and stored as glycogen in muscle and liver and breakdown of liver glycogen maintains blood glucose conc between meals (MUSCLE CANNOT RELEASE GLUCOSE BACK INTO BLOOD)
Liver function in protein synthesis
Amino acids from diet in fed state or muscle in fasted state
Amino acids enter liver and turn into secreted proteins that leave the liver as plasma proteins, clotting factors or lipoproteins
Liver function in transamination
Make dietary “non-essential” amino acids. Alpha-keto acid precursor (carboxylic acid and ketone group) and exchange of an amine group from an amino acid to a keto-acid. Eg alanine enters the liver and can react with the keto acid (alpha keto glutarate) to produce the amino acid glutamate and the ketoacid pyruvate (needs transaminase enzyme plus cofactor). REVERSIBLE if there is a different transaminase to convert glutamate and pyruvate back to alanine and alpha keto glutarate.
What is the glucose alanine cycle
pyruvate + glutamate make alanine, which enters liver and reacts with alpha ketoglutarate to make glutamate and pyruvate.
The glutamate reacts with 4 ATP to make urea. Some urea leaves via blood. Pyruvate + 6ATP + urea makes glucose which is used in glycolysis
Why is glutamate a special amino acid in metabolism?
Chemically related to 2-oxoglutarate (=alpha ketoglutarate) - key in krebs
Can be reversibly converted into oxoglutarate by transaminases/glutamate dehydrogenase or into glutamine, an important nitrogen carrier and most common free aa in human blood plasma
What is special about alanine?
Main aa released from muscle during starvation. Important substrate for hepatic gluconeogenesis and alanine transamination and required for keeping up fasting blood glucose concentrations
Liver function in triglyceride metabolism
Triglyceride makes FA which in liver beta oxidation makes acetyl coA which goes into TCA
OR beta oxidation makes 2 acetyl coA makes acetoacetate
Both are tissue energy sources
Where is fat stored in the body?
Liver and adipose
What happens when glycogen stores are full?
Liver can convert XS glucose and aa to fat for storage
Lipoprotein synthesis in liver?
Glucose enters liver, makes glycerol and pyruvate
Pyruvate makes acetyl coA which makes FA and cholesterol.
Glycerol makes triacylglycerol and apoproteins, phospholipids, cholesterol, fatty acids (lipoproteins)
Lipoproteins make HDL, and VLDL which makes LDL and triglycerides in adipose tissue
What is the function of VLDL and what quality does it have?
It’s major role is to deliver FA to body tissues and has a high triacylglycerol component
What is the function of HDL and what quality does it have?
Mop up XS cholesterol in circulation and return to the liver so are known as good fat. They have high protein content but low fat content
What function does the LDL have and what quality?
It is high in cholesterol and deliver cholesterol to tissues which use the cholesterol to make hormones and maintain cell membrane integrity
What are the liver functions in storage?
Store fat soluble vitamins A, D, E and K and stores sufficient for 6-12 months apart from vit K which has a small storage
Storage of iron as ferritin for erythropoesis
What is vit k essential for?
Blood clotting
