The liver is the largest internal organ, weighing approximately 1.5 kg in adult humans. It is also an exocrine gland, secreting bile continuously. Bile is concentrated and stored in the gallbladder, an organ located on the inferior surface of the liver. The liver originates as a tubular gland of the intestine. It is remodeled during development around a system of blood vessels resulting in system of radial plates of hepatocytes surrounding a network of blood sinusoids.
Liver tissue is organized for efficient filtration of the portal circulation from the intestine.
The blood is filtered as it passes between the plates of hepatocytes, and its composition is regulated. The sinusoids drain into the central vein and the central veins then empty into sublobular veins. These in turn converge to form the hepatic veins that empty into the vena cava. The individual lobules function in parallel with one another, not in series. They are metabolically active and functionally versatile.