Liver

00:00 Let's, first of all, look at the liver. Shown here in this diagram is the classical structure or description of the structure of the liver. You can see the liver up on the smaller component on the top left-hand side. It has got two lobes.

00:20 It's supplied by the portal vein, and it's drained by the vena cava. That portal vein comes from the gut carrying all sorts of nutrients and other products absorbed from the gut. It's sent through the portal vein to the liver as part of the portal system.

00:40 And then the liver processes all those products that are absorbed. On the right-hand side of the diagram, you see the way in which the hepatic lobule is described.

00:52 It's a hexagonal-shaped structure. It consists of, firstly, in the center of these hexagons, a central vein. That central vein is going to take blood away from the lobules when that blood has secreted in it all the products that the hepatocyte produces. And those veins will then drain out of the liver into the vena cava. Below, you can see a lighter colored vein that's part of the portal vein. When that enters the liver, it divides into a number of branches.

01:29 And the branches of that portal vein travel up alongside the very corners of these hexagonal hepatic lobules. And the blood then flows from these into the sinusoids and into the central vein. The hepatic artery also enters the liver and travels up along these sides, these borders of the hexagon, and supplies the hepatocytes with oxygenated blood. These hepatocytes also make bile and they are secreted into little small bile canaliculi, and those canaliculi drain towards the periphery of these lobules into bile ducts, and therefore, they're transported away. So on the bottom left-hand side of the diagram, you can see these arrays of hepatocytes, sinusoids draining blood into the central vein, and then between these hepatocytes are thin little bile canaliculi draining bile back into the hepatic duct at the periphery. And at the periphery on the bottom left-hand side of this diagram, you can see the portal triad.

02:42 Portal triad is the hepatic artery, portal vein, and the hepatic duct, the bile duct.

02:50 On the right-hand side of this slide, you can see a section through the liver.

02:58 The large structures you see are branches of the large arteries and veins, and perhaps, ducts. The very bulk of this tissue though is composed of all the hepatocytes, that's stained brown color here.