Liver Anatomy and Function PDF

## Leveren - V. portae is larger than a. hepatica. - V. portae receives blood from the gastrointestinal tract, pancreas and spleen. - V. portae tributaries come from the same organs, which are supplied by unpaired visceral branches from the aorta abdominalis. - The exception to this is the live...

## Leveren - V. portae is larger than a. hepatica. - V. portae receives blood from the gastrointestinal tract, pancreas and spleen. - V. portae tributaries come from the same organs, which are supplied by unpaired visceral branches from the aorta abdominalis. - The exception to this is the liver. - A. hepatica comes from an unpaired visceral aortic branch, *truncus coeliacus*. ### The Liver's Efferent Vessels - The liver's efferent vessels, the hepatic veins (*vv. hepaticae*) do not pass through the *porta hepatis* but empty into the *v. cava inferior* at the bottom of the depression on the liver where the vein lies. ### The Liver Parenchyma - The liver parenchyma consists of prismatic *liver lobules*. - The *liver lobules* are separated by small amounts of connective tissue. - A *liver lobule* has five to six sides and is about 1 millimeter tall. - It's built around the *v. centralis*. - The *liver lobule* is composed of cubic liver cells. - The cells are located in plates extending from *v. centralis* to the *liver lobule*'s surface. ### The Liver Cell Plates - The *liver cell plates* are perforated and anastomose. - Between the plates are blood-filled *sinusoids*. - Blood cells in the *sinusoids* do not make direct contact with the *liver cells* because the *cell plates* are coated with *endothelial-like cells*. - Some of these cells are phagocytic and called *Kupffer's star cells*. ### The "Glisson's Triad" - Two *liver lobules* can be seen in Figures 69 and 71. - The area in Figure 71 is excised and magnified. - *V. centralis* can be seen in both drawings. - The three structures (7, 8 and 9) ("Glisson's Triad") are located in the connective tissue between the three *liver lobules*. - The presence of phagocytic cells in the capillary wall is a prerequisite for the use of the term *sinusoid*. - *Sinusoids* are defined as capillaries that are larger in diameter than usual, with phagocytic cells in the wall. - The term "*Kupffer's star cells*" is only used to describe the phagocytic cells of the liver *sinusoids*. ### The Liver's Sinusoids - The *sinusoids* receive blood from the liver's two afferent vessels, *v. portae* and *a. hepatica*. - Branches from these vessels empty into the *sinusoids* at the *liver lobule*'s surface. - Mixed venous and arterial blood flows through the *sinusoids* to *v. centralis*, and from there to the liver's efferent vessels, *vv. hepaticae*. - All *sinusoids* receive both venous and arterial blood, and this "mixed" blood flows toward *v. centralis*. ### The Liver's Role - The *liver cells* can absorb substances that the liver needs to process, and the *phagocytic cells* can absorb bacteria from the gut that pass by. - Blood from *v. centralis* flows through larger and larger veins, and leaves the liver through the *vv. hepaticae*. - Blood in * v. portae* goes through two sets of capillaries, a peripheral set, for example in the gut, and a central set in the liver, "liver capillaries" or *sinusoids*. ## The Biliary Ducts - The *biliary ducts* are made up of different structures: - *Gallbladder* (1), *vesica biliaris* - *Cystic duct* (2), *ductus cysticus* - *Hepatic duct* (3), *ductus hepaticus* - *Biliary duct* (4), *ductus biliaris* ### The Gallbladder - The *gallbladder* (2), *vesica biliaris*, is pear-shaped. - It is located on the liver's visceral surface, with the wide end to the front. - The *gallbladder's* neck continues into the *cystic duct* (2), *ductus cysticus*. ### The Hepatic Duct - Underneath the *porta hepatis*, the *cystic duct* joins with the *hepatic duct* (3), *ductus hepaticus*. - The *hepatic duct* carries bile from the liver. - The two ducts join together to form the *biliary duct* (4), *ductus biliaris*, which is 7–8 centimeters long and runs from the *porta hepatis* to the *duodenum* (7). ### The Biliary Duct - The *biliary duct* first runs over the *duodenum*, then behind the *duodenum* (stippled), and later behind the *pancreas*. - The end of the *biliary duct* (1) lies in the *duodenum* wall. - It merges with the *pancreatic duct* (2), and the two ducts combine to create a dilated common duct (3), which is surrounded by a circular muscle. - The dilated common duct opens onto the papilla of Vater (4). ### Pancreatic Cancer - A tumor in the *pancreas* can press on the *biliary duct* and cause jaundice.