The liver has two major
lobes and two minor lobes. Anteriorly, the right lobe is separated from the
smaller left lobe by the falciform ligament. Inferiorly, the caudate lobe is
near the inferior vena cava, and the quadrate lobe is adjacent to the
gallbladder. The falciform ligament is responsible for attaching the liver to
the anterior...
The liver has two major
lobes and two minor lobes.
Anteriorly, the right lobe
is separated from the smaller left lobe by the falciform ligament. Inferiorly,
the caudate lobe is near the inferior vena cava, and the quadrate lobe is
adjacent to the gallbladder.
The falciform ligament is
responsible for attaching the liver to the anterior abdominal wall and the
diaphragm by way of the coronary ligament, the upper layer of which is exposed
as if the liver were to be pulled away from the diaphragm.
A ligamentum teres is
continuous along the free border of the falciform ligament; this is a remnant
of the umbilical vein of the fetus. The porta of the liver is where the hepatic
artery, portal vein lymphatics, and nerves enter the liver and where the
hepatic ducts exit. Although the liver is the largest internal organ of the
body, it is only one to two cells thick. This is due to the fact that
hepatocytes, or liver cells, are only one to two cells thick and separated from
one another by large capillary spaces called sinusoids. The plate structure of
the liver and the high permeability of the sinusoids allow each hepatocyte to
be in close contact with the blood.
The hepatic plates are
arranged into functional units called liver lobules. The middle of each lobule
houses a central vein; at the periphery of each lobule are branches of the
hepatic portal vein and the hepatic artery, each of which opens into spaces
between hepatic plates. Arterial blood and portal venous blood contain nutrient
molecules absorbed in the gastrointestinal tract; they mix as the blood flows from
the periphery of the lobule to the central vein. The central veins of the
lobules converge to form two hepatic veins which then carry blood from the
liver to the inferior vena cava.
Bile is produced in the
liver by the hepatocytes and is secreted into thin channels called bile
canaliculi located within each hepatic plate. The canaliculi are drained
peripherally by bile ducts, which in turn drain into hepatic ducts that carry
bile away from the liver. As a result, blood travels in the sinusoids and bile travels
in the opposite direction so that blood and bile never mix in the lobules of
the liver under normal conditions. Cirrhosis, an irreversible liver disease,
destroys large numbers of liver lobules and replaces them with a permanent type
of connective tissue called regenerative nodules. These nodules don't have the
plate-like structure of normal liver tissue, and are consequently less
functional. Cirrhosis is often accompanied by the presence of ammonia from the
hepatic portal vein on into systemic circulation. Any disease that attacks
liver cells, such as viral hepatitis, or chemicals affecting the liver, such as
seen in chronic alcohol abuse, may bring about cirrhosis.
537,
Varghese Plaza,
1st
Floor, Vetturnimadam,
Nagercoil.
04652-224337,
9500946903.
anitpromoters@gmail.com
No comments:
Post a Comment