Recommendations / 07/11/2020

What is the direction of blood flow in the hepatic lobule?

In the hepatic lobule, blood enters the lobule via the portal vein and hepatic artery, located within portal triads (PT). This venous and arterial blood then combines and drains through hepatic sinusoids towards the central vein (CV). The direction of blood flow is shown as red arrows.

Does bile flow into or out of the liver lobule?

The classic liver lobule is enveloped by a limiting plate of hepatocytes, surrounded by various vessels embedded in connective tissue. The blood flows from the periphery via the sinusoids into the central vein (violet arrow). The bile flows in the opposite direction (green arrow).

What percentage of this blood flow comes from the hepatic portal system?

The hepatic portal vein supplies 75% of the blood to the liver, while the hepatic arteries supply the remaining 25%.

What is the hepatic lobule?

The hepatic lobule is the anatomic unit of the liver. In the anatomic model, liver lobules are organized into irregular polygons demarcated by connective tissue and composed of plates of hepatocytes radiating outward from the central vein to the portal triads (Figure 61-1).

What is the role of hepatic portal circulation?

The hepatic portal system is the venous system that returns blood from the digestive tract and spleen to the liver (where raw nutrients in blood are processed before the blood returns to the heart). They unite to form the hepatic portal vein near the anterior tip of the dorsal lobe of the pancreas.

What affects hepatic blood flow?

External factors which influence hepatic blood flow: during positive pressure ventilation or heart failure) Cardiac output: influences hepatic arterial flow directly, and portal flow indirectly (eg. in heart failue) Shock states and exercise: decrease splanchnic blood flow, both portal and hepatic.

What causes increased blood flow to the liver?

The most common cause of portal hypertension is cirrhosis, or scarring of the liver. Cirrhosis results from the healing of a liver injury caused by hepatitis, alcohol abuse or other causes of liver damage. In cirrhosis, the scar tissue blocks the flow of blood through the liver and slows its processing functions.

Where does blood and bile flow in the liver?

■ Figure 18.21 The flow of blood and bile in a liver lobule. Blood flows within sinusoids from a portal vein to the central vein (from the periphery to the center of a lobule). Bile flows within hepatic plates from the center to bile ductules at the periphery of a lobule.

How are the lobules of the liver drained?

18.21). These bile canaliculi are drained at the periphery of each lobule by bile ducts, which in turn drain into hepatic ducts that carry bile away from the liver. Since blood travels in the sinusoids and bile travels in the opposite direction within the hepatic plates, blood and bile do not mix in the liver lobules.

Where are the hepatocytes located in the lobule?

As you can observe above, a lobule is a roughly hexagonal arrangement of plates of hepatocytes radiating outward from a central vein (CV) in the center. Central veins are quite prominent and provide an easy means of orientation in sections of liver. At the vertices of the lobule are regularly distributed portal…

What are the Triads of the liver lobule?

Liver Lobule. Hepatic triads are areas present at each corner of the lobule. They contain two blood vessels and a bile ductule. The vein is a branch of the hepatic portal vein, and the artery is a branch of the proper hepatic artery. They both supply the blood to the sinusoids giving them a mix of nutrient rich,…

Where does blood flow through the hepatic lobule?

In all three species, blood and bile flow in opposite diections through the hepatic lobule. Hepatic plates, in all three species, are columns of hepatocytes extending from the portal regions to central veins and are lined by porous sinusoidal endothelium.

What is the structure of the liver lobule?

Liver Lobule. They contain two blood vessels and a bile ductule. The vein is a branch of the hepatic portal vein, and the artery is a branch of the proper hepatic artery. They both supply the blood to the sinusoids giving them a mix of nutrient rich, deoxygenated blood and freshly oxygenated blood from the celiac trunk.