Hepatic lobuleThe liver is built of thousands of these small hexagonal units.
Central veinBlood from the sinusoids drains into it, then out of the liver.
HepatocytesThey process nutrients, store glycogen, detoxify and make bile.
SinusoidsLeaky capillaries where blood from the triads mixes. It flows to the central vein.
The portal triad 4
Portal triadA hepatic portal vein branch, hepatic artery branch and bile duct.
Hepatic portal vein branchIt brings nutrient-rich blood from the gut.
Hepatic artery branchIt brings oxygen-rich blood.
Bile ductBile made by the hepatocytes flows out of the lobule through it.
Inside a sinusoid 2
Bile canaliculiBile collects in them and flows toward the bile ducts.
Kupffer cellsMacrophages that clean worn-out blood cells and germs from the blood.
How this list was compiled: Every name and detail checked on 2026-09-29 against OpenStax Anatomy and Physiology 2e, section 23.6 Accessory Organs in Digestion (hepatic lobules, central vein, portal triads of hepatic portal vein, hepatic artery and bile duct branches, hepatocytes, sinusoids, reticuloendothelial or Kupffer cells, bile canaliculi), https://openstax.org/books/anatomy-and-physiology-2e/pages/23-6-accessory-organs-in-digestion-the-liver-pancreas-and-gallbladder, and against Wikipedia, text only: Lobules of liver, Liver sinusoid, Kupffer cell and Bile canaliculus. Licence: own work
The drawing: Drawn for this site on 2026-09-29 from plain geometry; nothing traced. Licence: own work
How it works
The liver is built of thousands of tiny six-sided lobules. The first drawing is one lobule with a portal triad at each corner; the second enlarges one of the sinusoids that carry blood through it.
Read the full guide
Blood in at the corners, out in the middle
Numbers 1 to 4 are the lobule: its outline, the central vein, the plates of hepatocytes and the sinusoids between them. Numbers 5 to 8 are a portal triad and its three tubes. Numbers 9 and 10 are up close: the bile canaliculi between cells and a Kupffer cell in the sinusoid.
Blood flows in from the corners to the central vein; bile flows the other way, out to the bile ducts at the corners.
Questions and answers
What is a portal triad?
A group of three tubes at each corner of a liver lobule: a branch of the hepatic portal vein, a branch of the hepatic artery and a bile duct.
What are hepatic sinusoids?
Leaky capillaries between the plates of hepatocytes. Blood from the portal vein and hepatic artery mixes in them and flows toward the central vein, while the liver cells take up and release substances.
What do Kupffer cells do?
They are macrophages in the sinusoids that remove worn-out red blood cells, bacteria and debris from the blood passing through the liver.