The accessory organs: Pancreas, liver and gallbladder
Paul Ong, Rachel Skittrall in Gastrointestinal Nursing, 2017
Blood leaving the small intestine is rich in absorbed nutrients. It travels via the superior mesenteric vein to the hepatic portal vein where it then enters the liver. And 75% of the blood entering the liver is venous blood which enters via the hepatic portal vein. The remaining 25% of blood is arterial blood and this enters the liver via the hepatic artery. Blood enters the liver at the porta hepatis (doorway to the liver) via the hepatic artery and the hepatic portal vein. The blood enters the liver lobules via portal triads (Figure 6.10). There are six portal triads, one for each corner of the hexagonal-shaped lobule. A portal triad consists of a branch of the hepatic artery, the hepatic portal vein and the bile duct. When blood enters the lobule via the portal triad, venous and arterial blood becomes mixed as it drains into sinusoids. Sinusoids are ducts in the liver tissue which function like ‘canals’ transporting the blood to the hepatocytes. As blood flows through the sinusoids it comes into contact with hepatocytes which then absorb nutrients and secrete synthesised molecules. If there is an excess of nutrients these are removed and stored and if there is a deficiency of nutrients these are released or synthesised by the hepatocytes. From sinusoids blood then flows into the central vein, hepatic vein and then into the vena cava.
Gastrointestinal Function and Toxicology in Minipigs
Shayne C. Gad in Toxicology of the Gastrointestinal Tract, 2018
The liver has six lobes separated by fibrous tissues, and the gallbladder is a sac located under the right central lobe. Minipig liver lobules have a portal triad (central artery, vein, and bile duct). Bile produced by pigs has a similar composition (Alvaro et al. 1986, Preube and Skaanild 2012) but is less concentrated than human bile (Nakayama 1969). While bile production is important to gastrointestinal physiology, the liver of minipigs shares many of the cytochromes seen in humans (Soucek et al. 2001, Skaanild and Friis 2002), making the pig an excellent model for drug absorption, metabolism, and toxicology.
The Abdomen
Kenneth D Boffard in Manual of Definitive Surgical Trauma Care: Incorporating Definitive Anaesthetic Trauma Care, 2019
The structures within the porta hepatis include the hepatic artery, portal vein, and bile duct. The portal triad is encased in an extension of Glisson's capsule, and thus relatively resistant to injury. The portal triad runs within the segments of the liver. The major hepatic veins (right, left and middle) have no valves, are not protected by an extension of Glisson's capsule and run between the segments of the liver. Difficult to control, life-threatening haemorrhage in the operating room is generally related to hepatic vein or retrohepatic IVC injury. The liver generally encases a portion of the retrohepatic cava, at times circumferentially. Full mobilization of the liver to expose the retrohepatic IVC requires division of this attachment. The major hepatic veins are 8–12 cm in length, the majority of which is intrahepatic. Injury to the major hepatic veins is generally to this portion of the veins and can be controlled by compression or suture ligation. The extrahepatic segments of the major hepatic veins are <2 cm in length and are less commonly injured. Injury to the extrahepatic portion of the major hepatic veins generally presents as exsanguinating haemorrhage and carries a high mortality.2 In addition, 3 to 11 short hepatic veins run directly from the liver to the IVC, can also be a source of haemorrhage, and must be identified and controlled if liver resection is necessary. The short hepatic veins can be large, especially if the right hepatic vein is found to be diminutive Finally, the liver parenchyma will tolerate ligation or embolization of hepatic artery branches, but the bile ducts will not. The bile ducts depend on the hepatic artery for their blood supply (Figure 9.4.2).3
Variations in the vascular and biliary structures of the liver: a comprehensive anatomical study
Published in Acta Chirurgica Belgica, 2018
Burak Veli Ülger, Eyüp Savaş Hatipoğlu, Özgür Ertuğrul, Mehmet Cudi Tuncer, Cihan Akgül Özmen, Mesut Gül
Blood is supplied to the liver by the proper hepatic artery and drained from the liver by the hepatic portal vein. Other hepatic veins also provide venous drainage. The branches of the proper hepatic artery, hepatic portal vein, and common hepatic duct constitute the portal triad. The right portal triad exhibits a short course (1–1.5 cm) before entering the porta hepatis (a deep fissure on the inferior surface of the liver through which all neurovascular structures—except the hepatic veins—and the hepatic ducts enter or exit the liver). After entering the right lobe, the portal triad divides into anterior and posterior branches that supply the paramedian (V and VIII) and the lateral (VI and VII) segments [4]. The left portal triad continues to the top of the hepatoduodenal ligament and then moves 3–4 cm to the left to run under the quadrate lobe. The triad then turns forward, accessing segments II, III, and IV from the ligamentum venosum fissure [5,6]. The caudate lobe has a left portion of fixed size and a right portion that varies individually in size. Both the right and left portal triads drain blood from the caudate lobe and also drain bile. The caudate process, which is on the right, delivers venous blood to branches from the fork of the hepatic portal vein and the right branch of that vein; the left part of the caudate lobe delivers blood only to the left branch of the hepatic portal vein. The combined venous blood from the caudate lobe drains into the inferior vena cava via a single vein [7].
Induction of hepatic portal fibrosis, mitochondria damage, and extracellular vesicle formation in Sprague-Dawley rats exposed to copper, manganese, and mercury, alone and in combination
Published in Ultrastructural Pathology, 2020
Priyanka Dhanraj, Chantelle Venter, Megan Jean Bester, Hester Magdalena Oberholzer
The general morphology of the liver tissue for the control and the single, double, and triple metal-exposed groups (Figures 1 and 2) was evaluated. In the control group (Figure 1(a and b)), the typical arrangement of hepatocytes with no hydropic swelling was observed. None to minimal sinusoidal dilation with the presence of erythrocytes and hydropic swelling (black arrows) of hepatocytes was observed in all the metal-exposed groups (Figure 1(c–p)). Binucleated hepatocytes (Bi) were also observed in the exposed groups, particularly in the area surrounding the central vein. Figure 2 illustrates the general structure of the portal triad consisting of a branch of the portal vein (PV), a branch of the hepatic artery (HA) and bile ductules (B), in loose stromal connective tissue. In contrast to the control (Figure 2(a)), accumulation of inflammatory cells (white arrows) in the exposed groups (Figure 2(b–h)) was observed.
A fully coupled porous media and channels flow approach for simulation of blood and bile flow through the liver lobules
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
A histological image of the liver tissue cross-section is shown in Figure 1b. The liver tissue consists of about a half to one million small units named lobules. Each lobule usually has a six-sided cross-section structure with 0.5 to 2013; Rezania et al. 2013). There is a vein located at the centre of each lobule, named as centrilobular or central vein, that carries blood out from the liver lobule (Figure 1(c and d)). At the vertices of each liver lobule, there exists a set of terminal vessels named Portal Tract (PT) or portal triad (Ricken et al. 2018). The blood is directed from portal tracts to the lobule centre through a sinusoid which is a small blood vessel of the open pore capillary type (Figure 1(d)). There is a hepatic portal capillary and a hepatic artery capillary that their streams are mixed across the sinusoid. The mixed blood flows towards the central vein joining to the main right, middle, and left hepatic veins and finally move towards the heart through the inferior vena cava (Rouiller 2013) (Figure 1(a)). As shown in Figure 1(d), there is also a set of Bile Ductules (BD) at the lobule vertices removing the produced bile from the lobule via a set of the bile canaliculi (or bile capillaries), in the opposite direction of the blood flow. The produced bile flows along the bile ductules to reach the gallbladder (Figure 1(a)).
Related Knowledge Centers
- Acinus
- Anatomy
- Hepatocyte
- Histology
- Tissue
- Ischemia
- Capillary
- Liver
- Central Veins of Liver
- Hepatic Artery Proper