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In histology (microscopic anatomy), the lobules of liver, or hepatic lobules, are small divisions of the liver defined at the microscopic scale. The hepatic lobule is a building block of the liver tissue , consisting of portal triads, hepatocytes arranged in linear cords between a capillary network, and a central vein .
proper hepatic artery (entering) hepatic portal vein (entering) The hepatic duct lies in front and to the right, the hepatic artery to the left, and the portal vein behind and between the duct and artery. It also transmits nerves and lymphatics. Sympathetic nerves - these provide afferent pain impulses from the liver and gall bladder to the brain.
Macroscopically, the liver has a pale and spotty appearance in affected areas, as stasis of the blood causes pericentral hepatocytes (liver cells surrounding the central venule of the liver) to become deoxygenated compared to the relatively better-oxygenated periportal hepatocytes adjacent to the hepatic arterioles.
The hepatic vein subsequently drains into the inferior vena cava. The hepatic artery provides 30 to 40% of the oxygen to the liver, while only accounting for 25% of the total liver blood flow. The rest comes from the partially deoxygenated blood from the portal vein. The liver consumes about 20% of the total body oxygen when at rest.
Portal hypertension is defined as increased portal venous pressure, with a hepatic venous pressure gradient greater than 5 mmHg. [3] [4] Normal portal pressure is 1–4 mmHg; clinically insignificant portal hypertension is present at portal pressures 5–9 mmHg; clinically significant portal hypertension is present at portal pressures greater than 10 mmHg. [5]
The condition is commonly associated with vascular and cardiac changes associated with aging but can be caused by many other conditions, including congestive heart failure, kidney failure, liver cirrhosis, portal hypertension, trauma, alcoholism, altitude sickness, pregnancy, hypertension, sickle cell anemia, a compromised lymphatic system or merely long periods of time sitting or standing ...
Portal venous pressure is the blood pressure in the hepatic portal vein, and is normally between 5 and 10 mmHg. [1] Raised portal venous pressure is termed portal hypertension, [2] and has numerous sequelae such as ascites and hepatic encephalopathy. [3] [4]
Ischemic hepatitis, also known as shock liver, is a condition defined as an acute liver injury caused by insufficient blood flow (and consequently insufficient oxygen delivery) to the liver. [5] The decreased blood flow ( perfusion ) to the liver is usually due to shock or low blood pressure.