Liver structure and function Flashcards
What surface areas of the abdomen is the liver in?
Right hypochondriac & epigastric region
What is the anatomical relationship between the liver and the diaphragm?
Liver is tucked against the inferior surface of the diaphragm
The liver is made up of lobes
What are these called?
2 major lobes –> Left & right
2 minor lobes –> Caudate & quadrate
Which major lobe of the liver is bigger?
Right
What is the Porta of the liver?
Site of entry/exit of Blood vessels, lymph vessels, ducts and nerves
Located on the inferior surface of the liver
(btec version of the hilum of a lung)
What blood vessels enter the porta of the liver?
Hepatic portal vein
Hepatic artery
What ducts leave the porta of the liver?
right/left hepatic ducts
these fuse to form the common hepatic duct
What nerve(s) would you expect to see in the porta of the liver?
The hepatic nerve plexus
What is the fate of the ducts that leave the porta of the liver?
right/left hepatic ducts join and form the common hepatic duct
common hepatic duct is joined by the cystic duct (from gallbladder) to form the common Bile duct
When looking at the liver from the front, what separates the right and left major lobes?
The Falciform ligament
What small organ would you find to the immediate left of the quadrate lobe?
Gallbladder
How are the 2 minor lobes of the liver related anatomically?
The caudate lobe is superior to the quadrate lobe
They are located above and below the porta respectively
What covers the liver?
Liver covered by connective tissue capsule and visceral peritoneum
Except for bare area on the right lobe (small area on diaphragmatic surface surrounded by coronary ligament)
At the porta of the liver, some freaky shit happens with the connective tissue capsule
What is it and why does it do this?
CT capsule branches into a network of septa within the body of the liver
(imagine the roots of a tree going into the ground)
It does this for structural support
The septa within the liver are ‘followed about’ by 3 things.
What are they?
Vessels, ducts and nerves
These follow about the septa
The network of septa in the liver end up dividing it into ‘Hexagonal lobules’
What is found in these?
Portal triad at each corner of the lobule:
- hepatic portal vein
- hepatic artery
- hepatic duct
Also nerves and lymph vessels
What is the fate of the veins that originate in hexagonal lobules in the liver?
Central veins at each lobule –> Hepatic veins
The hepatic veins eventually feed into the IVC
What are hepatic cords?
Small chains of Hepatocytes (functional cells of the liver) located in hexagonal lobules
They radiate out from the central vein of the lobule, to the edge (like spokes on a bike wheel)
What are the spaces between hepatic cords called?
Hepatic sinusoids (blood vessels supplying hepatocytes)
What is the ‘Bile canaliculus’?
Cleft-like lumen that lies between cells within each hepatic cord
pre-cursors to the ducts
Note they are different from sinusoids - ie they are not outside of the hepatocyte bits (look up diagram)
What is the liver’s role in digestion?
production & secretion of bile
What are the 6 components of bile?
Bile acids Lecithin Cholesterol Bile pigments Toxic metals Bicarbonate (HCO3-)
Do hepatocytes secrete all the components of bile?
Nah
Bile acids, Lecithin, Cholesterol, Bile pigments and toxic metals are all secreted by hepatocytes
Bicarbonate is produced by Duct cells
What is the key ingredient in bile pigment?
Bilirubin (from haemoglobin)
from old/damaged erythrocytes
Describe the production/secretion process for bile acids
Synthesised in liver from cholesterol (0.5g/day)
Before secretion, bile acids conjugated with glycine or taurine to make Bile Salts (more soluble)
Secreted bile salts recycled via enterohepatic circulation
Where is the gallbladder located in relation to the liver?
Located on the inferior surface of the liver
What are the 3 layers of the wall of the gallbladder?
mucosa (folded rugae expansion)
muscularis (smooth muscle) contraction
serosa (connective tissue)
What duct comes from the gallbladder?
Cystic duct
What is the sphincter of Oddi?
the smooth muscle that surrounds the end portion of the common bile duct and pancreatic duct
Used to control the flow of bile, enzymes etc into the duodenum
What happens to bile inside the gallbladder and how?
Gets mad concentrated (5-20x) due to extraction of Na+ and H2O from the bile
What causes relaxation of the Sphincter of Oddi?
Fat/amino acids in duodenum causes CCK release
CCK causes relaxation (as well as other things)
