Liver Circulation And Portal Hypertension Flashcards
Porta hepatis
Entrance and exit point of the liver
Contains several structures:
-Hepatic artery proper
-Portal vein
-Common hepatic duct:
-formed by the fusion of left and right hepatic duct that happens at this level.
-Hepatic nerve plexus:
-made by fibers from the Vagus nerve and sympathetic nerves from celiac trunk.
-Lymphatic vessels
Liver 🩸supply
25% of the liver blood supply is carried out by the hepatic artery proper
75% of the liver blood supply is carried out by the portal vein.
Hepatic artery proper
From abdominal Aorta
-Celiac trunk: makes 3 branches
1)Left gastric artery
2)Splenic artery → Pancreatic arteries
3)Common hepatic artery:
-branches before entering the liver
-Gastroduodenal artery
-Hepatic artery proper → enters the liver→ left and right hepatic arteries for left and right hepatic lobes
-Right hepatic artery
→ cystic artery: supplies the gallbladder.
This is oxygen-rich blood
Portal vein
Carries 75% of the blood received by the liver
-It’s 🩸from the GI tract: rich in nutrients but also toxins, alcohol, drugs…
Portal vein receives
-pancreatic vein: from pancreas
-splenic vein: from spleen
-gastric vein: from stomach
-intestines
Portal vein receiving pancreatic vein
Carries also hormones like insulin:
-allows to have absorption of carbohydrates into hepatocytes
-because Insulin is a super anabolic hormone, responsible for Protein synthesis, lipogenesis, glycolysis, amino acid uptake, etc.…. so,
it’s important for the pancreas to send some of its insulin to the liver in the fed state especially and not have all of it sent to the systemic circulation.
Portal vein receiving splenic vein
-The spleen is a secondary lymphoid organ:
-contains sinusoids (cords of Billroth) that are responsible for eliminating old erythrocytes (hemocatheresis)
-Waste products like bilirubin are brought back to the liver through portal circulation
➡️bilirubin is used to make more bile
Portal veins receiving gastric veins
Not a lot of reabsorption happens in the stomach → primarily lipid-soluble substances like aspirin and alcohol
that are brought back to the liver to be eliminated
Portal veins receiving intestines
They are supplied by 2 arteries:
-Superior mesenteric artery:
-branch of abdominal Aorta,
-supplies from duodenum to 2/3 of transverse colon
-Inferior mesenteric artery:
-branch of abdominal Aorta,
-supplies from final 1/3 of transverse colon to superior aspect of rectum
They are drained by:
-Superior mesenteric vein
-Inferior mesenteric vein
Substances that are carried through the liver through portal circulation
-Drugs
-Hormones: insulin, glucagon, somatostatin…
-High amount of nutrients
-Pathogens: usually contained in food
-Includes bacteria, viruses, toxins.
It’s poorly oxygenated blood
Termination
The portal vein enters the liver through the porta hepatis and branches in hepatic portal venules
➡️they are directed to each pole of liver lobule
-Portal venules, hepatic arterioles (from hepatic artery proper) and bile ducts are bound together at each
pole of the hexagon → Hepatic triad.
-Both the hepatic arterioles and portal venules empty their blood in capillaries called sinusoids → central vein → hepatic veins → IVC → systemic circulation
Anatomy of liver
-The liver is the largest organ of the body.
-Its structural and functional unit is the hepatic lobule:
has hexagonal shape
-Intraperitoneal organ: enveloped by 2 layers of peritoneum (visceral and parietal)
-The liver occupies 3 of the 9 quadrants in which the
abdomen can be subdivided:
-right hypochondriac,
-epigastrium,
-part of the left hypochondriac.
Diaphragmatic surface:antero superior surface
-In contact with the inferior surface of diaphragm.
-The right and left lobes are visible
-Separated by falciform ligament
Visceral surfaces: postero-inferior surface
-4 lobes visible
-falciform ligament reflects backwards
-ligamentum venosum
-ligamentum teres
-anterior and posterior coronary ligaments:
-reflects of peritoneum
-anchor the liver to diaphragm
-bare area: small portion of liver that isn’t covered by peritoneum
-cystic fossa: where gallbladder is located
4 lobes
-Right lobe
-Left lobe
-Caudate lobe:
-delimited by ligamentum venosum, IVC and porta hepatis.
-Quadrate lobe:
-delimited by ligamentum teres and gallbladder
Falciform ligament
-forms left and right triangular ligaments:
-anchor the liver to diaphragm
Ligamentum venosum
remnants of ductus venosus from fetal life
Ligamentum teres
-goes from porta hepatis to inferior border of the liver.
-Remnant of umbilical vein in fetal life
→ blood flowed from here through the ductus venosus and into IVC
