=== Blood Supply to a Lobule ===

At the periphery of the lobules, in the angles between 2 or 3 adjacent lobules, lie the interlobular septa or portal canals consisting of connective tissue, and containing a branch of the hepatic artery, a branch of the portal vein, a small bile duct, a lymphatic vessel and small nerves. The blood that enters a lobule is supplied from the vessels in the portal system. Both venous and arterial blood enters a lobule. The venous blood enters the sinusoids directly from the smallest branches of the portal vein. Only a small volume of arterial blood enters the sinusoids directly from the smallest branches of the hepatic artery. Most of the arterial blood goes through a capillary bed to enter the small branches of the portal vein before going on to the sinusoids. Blood in the sinusoids “bathes” the hepatocytes before passing into the central vein from which it flows into a sublobular (intercalated) vein. Sublobular veins progressively unite to form the collecting veins that progressively join to form the hepatic veins. Two or more hepatic veins empty directly into the inferior vena cava.

== Gallbladder ==

The pear-shaped gallbladder shows marked variation in size and shape among different individuals. Anatomically, it consists of a neck, a body, and a blindly ending fundus. Histologically, its wall consists of a mucosa, a muscularis, a perimuscular layer of connective tissue, and a serosa or fibrosa.