Liver

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The liver is the largest internal organ in humans and plays a central role in metabolic processes and removing toxins from the blood. It is covered by a fibrous capsule, also known as Glisson's capsule. Histologically, it is made up of functional units known as liver lobules, which have a central vein and are bordered by extensions of the fibrous capsule of the liver (interlobular septae). Where several lobules meet, a portal area is formed, which contains connective tissue, nerves and lymphatic vessels as well as a portal triad, consisting of a branch of the portal vein and hepatic artery as well as an interlobular bile duct. It is important to be aware that the flow of bile is countercurrent to the flow of blood.

The parenchyma of the liver consists of specialized epithelial cells called hepatocytes. These store glycogen and synthesize bile and fatty acids as well as various proteins. The hepatocytes are arranged in bar-like plates known as hepatic cords, between which there are hepatic sinusoids and bile canaliculi.

Hepatic sinusoids are dilated capillaries that contain mixed blood from the portal vein and the hepatic artery. Stellate macrophages, also known as Kupffer cells, are specialized macrophages that phagocytose foreign particles and dead cells are also found here. There is a perisinusoidal space (of Disse) around the sinusoids, which is important for the exchange of substances between hepatocytes and the blood.

Watch the following video to learn more about the histological appearance of the liver:

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