Final answer:
The structure with a 6-sided shape and a centralized vein with portal triads is the liver lobule. It contains hepatocytes, is bordered by a portal triad consisting of a bile duct, hepatic artery branch, and hepatic portal vein branch, and functions as the main metabolic unit of the liver.
Step-by-step explanation:
The 6-sided structure with a centrally located vein and portal triads is known as a liver lobule. The liver lobule is a hexagonal-shaped structure consisting of hepatocytes, bile canaliculi, and hepatic sinusoids. Hepatocytes are the liver's main cell type and account for around 80 percent of its volume. They are arranged in hepatic laminae radiating out from the central vein of each lobule. The portal triad, found at the edges of the hepatic lobule, is made up of three key components: a bile duct, a branch of the hepatic artery, and a branch of the hepatic portal vein.
The hepatic artery supplies oxygenated blood to the liver, while the hepatic portal vein brings nutrient-rich blood from the gastrointestinal tract and waste from the spleen. Blood from both sources flows through the fenestrated capillaries of the sinusoids, where it comes into close contact with hepatocytes for processing. This system ensures that toxins are filtered and nutrients are metabolized effectively. After processing, blood flows to the central vein and then to the hepatic vein, entering the inferior vena cava, while bile flows in the opposite direction into bile canaliculi.