Vasculature of the human liver
Blood vessels associated with the liver
Hepatic veins
Hepatic portal vein
Hepatic artery
Hepatic artery branches off the celiac artery and in turn branches off into the hepatic artery proper, as well as the gastroduodenal and right gastric artery. The hepatic artery proper provides oxygenated blood to the gall bladder as well the liver (via branching into the left and right hepatic artery)
Hepatic veins are a collection of three larger upper veins in addition to the six to twenty lower hepatic veins. They lack valves and together, they drain deoxygenated blood from the liver and merges into the inferior vena cava.
Hepatic portal vein brings blood from the gastrointestinal tract to the liver. The portal vein accounts for almost 75% of blood delivered to the liver, and conducts blood to capillaries in the liver for absorption of its contents.
The hepatic portal vein brings in nutrients and toxins from digestion from the intestinal tracts. This is so that the liver can process the nutrients and remove the toxins, some contents of the hepatic portal vein includes:
Ethanol (broken down into acetaldehyde, acetic acid and acetyl-CoA)
Amino acids (deaminated into urea)
Fructose and galactose (converted into glucose)
The liver receives dual blood supply from the hepatic artery and the hepatic portal vein, here are the advantages of this characteristics
The liver is a very active organ that needs an increased supply of oxygenated blood to function efficiently, necessitating the presence of a dual blood supply system.
The mixture of arterial and venal blood of the dual blood supply in the sinusoids allows the liver to receive not only oxygen-rich, but also nutrient-rich blood
Lobules are small hexagonal structures in the liver that are surrounded by branches of the hepatic artery and portal vein. These vessels drain blood into sinusoids, which are located in the lobules. The sinusoids, in turn, drain into a central vein in the lobule which drains into the hepatic vein.
The aforementioned sinuscoids are small blood vessels that allows for material exchange between the blood and the hepatocytes.
The sinusoids consists of an incomplete basement membrane and an endothelial membrane with intercellular gaps. These features allow for increased permeability, allowing larger molecules such as plasma proteins to pass through.
Differences between sinusoids and capillaries
Sinusoids have incomplete basement membranes and intercellular gaps, capillaries do not
Sinusoids are wider, capillaries are narrower
Exchange of materials more efficient in sinusoids because hepatocytes are in direct contact with blood components, whereas cells besides capillaries are not in contact with blood components