Hepatocytes & Parenchyma

These hepatocyte plates are typically acecellthick; although twocellthick plates occasionally occur. They also pass to be bent to form a lacunar meshwork. Within the meshwork, the sinusoids lead the mixed fall of the liverwort arterial kind vessel and introduction vein into the "labrinthus hepatis" (8:1011). Under normal slew each hepatocyte is open on two facial expressions by the blood of at least two different sinusoids (7:40). This perisinusoidal surface area represents up to 40% of the cell's surface area. Thus, the potential for interaction between the blood and the hepatocyte is considerable.

The main structural and functional unit of the liver is the acinus. The hepatic acinus is a distinct mass of hepatocytes which are perfused unidirectionally from the terminal admission venules to the hepatic portal venules (5:2). Thus, there is sequential perfusion of liver cells from the vascular core to the acinar periphery. This unidirectional flow and sequential perfusion tend to compartmentalize the processes which occur in the acinus. Different functions are emphasize to varying degrees in different hepatocytes, depending on their spatial position. This results in the progressive modification of the blood at various distances from the portal venule (5:16).

The human liver is highly vascularized (4:95). Approximately 75% of its blood comes from the portal vein and about 25% comes from the hepatic artery. The blood from the portal vein tends to be rich in both endogenous and

The canaliculi are sepa enumerated from the perisinusoidal and sinusoidal areas by junctional complexes. These complexes consist of desmosomes, gap junctions, mediocre junctions (zonula adhaerens) and tight junctions. Such structures serve as special tissue layer differentiations which act to hold the liver cells together.

It is the hepatocyte's plasma membrane which enables it to wad out these functions (1:xxix). On its perisinusoidal surface the membrane faces the space of Disse (5:3). This region of the sinusoid is bounded by the hepatocytes on one side and the liver's endothelial cells on the other.

Many of the substrates are ingested for subsequent entrepot or metabolism. For example, one function of hepatocytes is to store glycogen (2:14). The rate at which a substance is taken up by the liver and then metabolized and excreted, determines whether or not it will be stored. In general, the distribution of stored compounds within the liver's hepatocytes tends to be inhomogenous. This results, in part, from the fact that different cells tend to have different transport capacities. Hepatocytes set farther from the terminal portal venules, for instance, will be exposed to lower concentrations of substrates than those located more proximally. This will affect their dexterity to metabolize materials (7:41).

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