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The liver is the largest gland in the body, weighing between 1 and 2.3kg.It is a nutritional factory in the human body assimilating and supplying all the nutrients to all the tissues in the body.The liver is enclosed in a thin capsule and incompletely covered by a layer of peritoneum. Folds of peritoneum from supporting ligaments attaching the liver to the inferior surface of the diaphragm. It is held in position partly by these ligaments and partly by the pressure of the organs in the abdominal cavity. The liver is described as having four lobes . The two most obvious are the large right lobe and the smaller, wedge-shaped, left lobe. The other two, the caudate and quadrate lobes, are on the posterior surface. Location : Liver is situated in the upper part of the abdominal cavity occupying the greater part of the right hypocondriac region, part of the epigastric region and extending into the left hypocondriac region. Its upper and anterior surfaces are smooth and curved to fit the under surface of the diaphragm, its posterior surface is irregular in shape. Organs associated
with :
Superiorly and anteriorly -- diaphragm and anterior
abdominal wall Inferiorly-- stomatch, bile ducts,
duodenum, right colic flexure of the right kidney and
adrenal gland colon,posteriorly-- oesophagus, inferior
vena cava, aorta, gall bladder , vertibral column and
diaphragm Laterally-- ower ribs and diaphragm
The portal fissure : This is the name given to the part on the posterior surface of the liver where various structures enter and leave the gland. The portal vein enters, carrying blood from the stomatch, spleen, pancreas and the small and large intestines. The hepatic artery enters, carrying arterial blood. It is a branch from the coeliac artery which is a branch from the abdominal aorta. Nerve fibres, sympathetic and parasympathetic. The right and left hepatic ducts leave, carrying bile from the liver to the gall bladder. Lymph vessels leave the liver, draining some lymph to abdominal and some to thoracic nodes. Blood supply: The hepatic artery and the portal vein take blood to the liver. Hepatic veins, varying in number, leave the posterior surface and immediately enter the inferior vena cava just below the diaphragm . The structure : The lobes of the liver are made up of tiny lobules just visible to the naked eye. These lobules are hexagonal in outline and are formed by cubical-shaped cells, the hepatocytes, arranged in pairs of columns radiating from a central vein. Between two pairs of columns of cells there are sinusoids (blood vessels with incomplete walls) containing a mixture of blood from the tiny branches of the portal vein and hepatic artery. This arrangement allows the arterial blood and venous blood (with a high concentration of nutritional materials) to mix and come into close contact with the liver cells. Some cells, lining the sinusoids, are hepatic macrophages(Kipffer cels). Blood drains from the sinusoids into central or centrilobular veins. These then join with veins from other lobules, forming larger veins, until eventually they become the hepatic veins which leave the liver and empty blood into the inferior vena cava just below the diaphragm. One of the functions of the liver is to secrete bile. The bile canaliculi run between the columns of liver cells. This means that each column has a blood sinusoid on one side and a bile canaliculus on the other. The canaliculi join up to form larger bile canals until eventually they form the right and left hepatic ducts which drain bile from the liver. Lymphoid tissue and a system of lymph vessels are present in each lobule. If you have to know more about liver ,then click here.
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