Liver, Biliary and Exocrine Pancreatic Physiology Quiz

See Lobule Architecture and Opposing Flows. Option D is correct. Blood and bile run in opposite directions through the lobule. Mixed blood from the portal vein (nutrient-rich, from the gut) and the hepatic artery (oxygenated) enters at the portal triad at the edge of the lobule. It crosses the sinusoids, the leaky capillary channels between plates of hepatocytes (the main liver cells), and leaves through the central vein, so blood flows portal-to-central. Bile is made by the hepatocytes and secreted into bile canaliculi, tiny channels between neighbouring cells. These drain outwards to the bile ductules of the portal triad and then into the larger bile ducts, so bile flows canalicular-to-portal. This opposition places newly formed bile at the periphery, where it can leave without fighting the venous outflow, and it means hepatocytes near the portal triad meet the freshest blood. Memory aid: blood goes portal-to-central and bile goes canalicular-to-portal, so the two streams pass each other like traffic on a two-way road.

• Blood: flows portal-to-central, from the portal triad across the sinusoids to the central vein.
• Bile: flows canalicular-to-portal, from the bile canaliculi to the ductules of the portal triad.
• Direction: blood and bile run in opposite directions through the lobule.