Schema of a hepatic acinus (the functional subunit of a hepatic lobule) in cross-section illustrating blood and bile flow relative to the portal tract (zone 1)—in this case a portal triad—and centrilobular (zone 3) regions. The portal field (containing portal venule, bile ductule and hepatic arteriole) is connected to the central vein by sinusoids. Hepatocytes, endothelial cells and many other cells types are exposed to blood flowing centripedally from the portal to the central area. Bile flows centrifugally towards the portal triad. In the sinusoids, nutrient-rich blood from the portal venule mixes with oxygen rich blood from the hepatic arteriole. Displayed are the orientation of hepatocytes with their canalicular conduits (green intercellular structures), single and occasionally double-wide hepatic cords, the smallest biliary ductular element (cholangiole), sinusoidal endothelium, intrasinusoidal Kupffer cells, and extrasinusoidal stellate cells (within the space of Disse).