The liver Flashcards
(39 cards)
Where is the liver?
In the right upper quadrant.
It is held in place by intraabdominal pressure.
The gallbladder is at the back underneath.
The kidneys and bladder are also underneath.
It shares a blood supply with the small intestine.
What is the structure of the liver?
It has right and left lobes, which are separated by the falciform ligament.
In the centre of each lobe is a central canal, which has the hepatic vein, from the inferior vena cava.
Hepatocytes and sinusoids branch from the central canal.
What is the blood supply of the liver?
The portal tracts lie at the periphery of each lobule and contains a bile duct, branch of portal vein and hepatic artery.
The hepatic artery brings in oxygenated blood from the lungs.
The portal vein has nutrient-rich blood from the intestines.
These then mix in the sinusoids.
What is the outside of the liver?
The liver is covered in a fibroconnective tissue capsule - the capsule of Glisson.
This is covered in peritoneum.
Thin connective tissue septa enter the organ and divide it into lobes and lobules from the capsule.
What are genetic variations in liver anatomy?
Hereditary anatomical displacement, accessory lobes
What are internal factors causing variations in liver anatomy?
Portal thrombosis - blood clot, cardiac cirrhosis, fibrosis and atrophy.
What are external factors causing variations in liver anatomy?
Impression effects - diaphragm, tight belts, coughing, Riedel’s and accessory lobes and clefts or fissures.
How is the liver connected to the gallbladder?
The liver secretes substances into the blood and bile.
The bile is stored in the gall bladder in between meals, then released during meals in the cystic duct, which drains into the common bile duct then enters the small intestine duodenum.
Its entry is controlled by the Sphincter of Oddi.
What triggers the gall bladder?
Food stimulates CCK release from I cells which triggers contraction of the gall bladder forces the bile into the common bile duct, and the smooth muscle in the sphincter of Oddi relaxes, which opens the sphincter so bile goes into the duodenum.
What are the functional bits of the liver?
The liver is divided into 8 segments, which all have separate blood supplies and drainage.
Each segment is divided into lobules and acinus, the functional units of the liver.
These are composed of hepatocytes, sinusoids, blood vessels and bile canaliculi.
What is the capsule of Glisson made from?
The connective tissue is made of ECM materials, mainly collagens 1,2,3,4,5,6 and produced by stellate cells.
Has a long half life.
Glycoproteins link cells to the collagen.
What is the function of the capsule of Glisson?
It is important in health and disease.
It protects the liver from injury.
It has niches for orientation and growth of cells.
What is cirrhosis?
Scarring causes disruption of the architecture and therefore function.
F0 is a healthy liver, F4 requires a liver transplant.
In F4, the liver is mostly filled by scarring, and there are not enough healthy cells to function properly - decompensation.
What are hepatocytes?
The main cell type in the liver, perform most of the function.
There are less in a diseased liver and with age.
They are big because of their large function, and do not turn over often because of the large energy requirement.
What is the structure of hepatocytes?
Polarised epithelial cells - the function changes across the liver.
Hepatocytes near the blood supply have structures for removing things from the blood and structures for secreting into the blood.
How is the liver specialised for storage?
The liver stores carbohydrates as glycogen.
The ER synthesises proteins and carbohydrates and are found near the blood supply so the products are secreted straight into blood supply.
What are at the sides of hepatocytes?
There are tight junctions which holds the liver together.
There is also the beginning of the canaliculus in which bile is produced and drained into.
What is biliary epithelium?
Barrier cells, or cholangiocytes.
Polarised epithelial cell.
Has a dense basement membrane due to bile being caustic (corrosive).
The main function is transport and secretion.
What do barrier epithelia do?
Form the bile canalicular and bile channels which go to the gall bladder.
The beginning of the bile canaliculus matures into a larger duct, which is lined by cholangiocytes to protect the liver from bile.
It then matures into a big duct which connects to the common bile duct.
They can modify the bile through secretions, pH, concentration.
How do biliary epithelium vary in size?
In zone 1 - where the blood supply of the liver is, the ducts are small and few number.
Towards the edges of the liver the duct cells are bigger and more polarised.
What is endothelium?
The cells that line the blood vessels, a barrier between the blood and the tissue.
What is the function of the endothelium?
Exchange materials between the blood and tissues.
Protect the body of the liver (parenchyma) from blood cells, viruses, toxins and bacteria.
Selectively allow materials and cells through - filtration.
What is anti-thrombogenic surface?
The endothelium has an anti-thrombogenic surface which means there are no blood clots formed unless damage is detected.
Endothelium is involved regulation of coagulation.
What are the types of liver endothelium?
Lymphatic, venous, sinusoidal, arterial, all have similar function
Sinusoidal have more uptake and scavenging properties
Functions of endothelium: clear waste, dying cells, tumour cells.
