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Liver
What is the Liver?
The liver is the largest glandular organ of the body. It weighs about 3 lb (1.36
kg). It is reddish brown in color and is divided into four lobes of unequal size and
shape. The liver lies on the right side of the abdominal cavity beneath the
diaphragm . Blood is carried to the liver via two large vessels called the hepatic
artery and the portal veinand bile duct . The heptic artery carries oxygen-rich
blood from the aorta (a major vessel in the heart). The portal vein carries blood
containing digested food from the small intestine. These blood vessels subdivide
in the liver repeatedly, terminating in very small capillaries. Each capillary leads
to a lobule. Liver tissue is composed of thousands of lobules, and each lobule is
made up of hepatic cells, the basic metabolic cells of the liver.
What is its major function?
The liver has many functions. Some of the functions are: to produce substances
that break down fats, convert glucose to glycogen, produce urea (the main
substance of urine), make certain amino acids (the building blocks of proteins),
filter harmful substances from the blood (such as alcohol), storage of vitamins
and minerals (vitamins A, D, K and B12) and maintain a proper level or glucose in
the blood. The liver is also responsible for producing cholesterol. It produces
about 80% of the cholesterol in your body.
Diseases of the Liver
Several diseases states can affect the liver. Some of the diseases are Wilson's
Disease, hepatitis (an inflammation of the liver), liver cancer, and cirrhosis (a
chronic inflammation that progresses ultimately to organ failure). Alcohol alters
the metabolism of the liver, which can have overall detrimental effects if alcohol
is taken over long periods of time.
Hemochromatosis can cause liver problems.
Medications that negatively effect the liver
Medications have side effects that may harm your liver. Some of the medications
that can damage your liver are: serzone, anti-cancer drugs (tagfur, MTX, and
cytoxan), and medications used to treat diabetes.
biliary system
The organs and ducts by which bile
is formed, concentrated, and carried
from the liver to the duodenum (the
first part of the small intestine). Bile
removes waste products from the
liver and carries bile salts, necessary
for the breakdown and absorption of
fat, to the intestine.
Bile is secreted by the liver cells and
collected by a system of tubes that
mirrors the blood supply to the
organ. This network of bile-drainage
channels carries the bile out of the
liver by way of the hepatic ducts,
The gallbladder and the ducts that carry bile and other
which join together to form a
digestive enzymes from the liver, gallbladder, and
common duct that opens into the
pancreas to the small intestine are called the biliary
duodenum at a controlled orifice
system
called the ampulla of Vater. Bile does
not pass directly into the duodenum
but is first concentrated and then
stored until needed in the gall
bladder, a pear-shaped reservoir lying in a hollow under the liver, to which it gains
access by way of the cystic duct.
When food is eaten, the presence of fat in the duodenum causes the secretion of a
hormone, which opens the ampulla of Vater and causes the gall bladder to contract,
squeezing stored bile via the cystic and common bile ducts into the duodenum. In the
duodenum, bile salts emulsify the fat, breaking it down to a kind of milk of
microscopic globules.
Excretory and Secretory Function
 One of the most important liver functions, and one that is disturbed in a large
number of hepatic disorders, is the excretion of bile.
 Bile comprises of bile acids or salts, bile pigments (primarily bilirubin esters),
cholesterol, and other substances extracted from the blood.
 The primary bile acids, cholic acid and chenodeoxycholic acid, are formed in the liver
from cholesterol.
The bile acids are conjugated with the amino acids glycine or taurine, forming bile salts
 Bile salts (conjugated bile acids) are excreted into the bile canaliculi by means of a
carrier-mediated active transport system.
 During fasting and between meals, a major portion of the bile acid pool is
concentrated up to 10-fold in the gallbladder.
 Bile acids reach the intestine when the gallbladder contracts after each meal.
 Bile is intimately involved with digestion and absorption of lipids.
 Bilirubin, the principal pigment in the bile, is derived from the breakdown of
hemoglobin when aged red blood cells are phagocytized by the reticuloendothelial
system, primarily in the spleen, liver, and bone marrow.
 Bilirubin is transported to the liver in the blood stream bound to proteins, chiefly
albumin. It is then separated from the albumin and taken up by the hepatic cells.
 A normally functioning liver is required to eliminate this amount of bilirubin from
the body.
 Almost all the bilirubin formed is eliminated in the feces, and a small amount of the
colorless product Urobilinogen is excreted in the urine.
 When the bilirubin concentration in the blood rises, the pigment begins to be
deposited in the sclera of the eyes and in the skin. This yellowish pigmentation in the
skin or sclera is known as Jaundice.
Disorders of the Liver
1. Jaundice
What is Jaundice?
Jaundice is a yellow color in the skin, the mucous membranes, or the eyes. The
yellow pigment is from bilirubin. Bilirubin is a byproduct of old red blood cells.
Blirubin is the yellow color you see when a bruise is healing.
Jaundice occurs when there are too many old red blood cells in the blood. If there
are too many red blood cells retiring for the liver to handle, yellow pigment builds
up in the body. When there is enough to be visible, jaundice results.
Jaundice is also called icterus and yellow skin.
What Causes Jaundice?
There are several causes of jaundice. Jaundice may result from various diseases
or conditions that affect the liver.
Some common causes of jaundice are:
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Hepatitis A
Hepatitis B
Hepatitis C
Hepatitis D
Liver cirrhosis
Liver cancer
Hepatitis E
Hemolytic anemia
Autoimmune hepatitis
Malaria
Types of Jaundice
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Newborn Jaundice
o Most babies have some jaundice during the first week of life. The
ordeal of birth can send many red blood cells to an early
retirement, and babies’ livers are often unprepared for the load.
Before Mom’s milk comes in and stooling begins in earnest,
bilirubin accumulates more easily. Jaundice is even more common
in premature babies.
Pathologic Jaundice
o Pathologic jaundice is the term used jaundice presents a health
risk. Pathologic jaundice can occur in children or adults. It arises
for many reasons, including blood incompatibilities, blood diseases,
genetic syndromes, hepatitis, cirrhosis, bile duct blockage, other
liver diseases, infections, or medications.
Can Jaundice be Treated?
Yes. Treatment of jaundice will depend on the cause.
Complications of Jaundice
If left untreated, jaundice can worsen and affect other parts of the body. In
newborns, untreated jaundice can cause kernicterus.
Classification of Jaundice
Jaundice is classified as unconjugated, hepatocellular, or cholestatic.
The first type, unconjugated, or hemolytic, jaundice, appears when the amount of
bilirubin produced from hemoglobin by the destruction of red blood cells or
muscle tissue exceeds the normal capacity of the liver to transport it or when the
ability of the liver to conjugate normal amounts of bilirubin into bilirubin
diglucoronide is significantly reduced by inadequate intracellular transport or
enzyme systems.
The second type, hepatocellular jaundice, arises when liver cells are damaged so
severely that their ability to transport bilirubin diglucoronide into the biliary
system is reduced, allowing some of the yellow pigment to regurgitate into the
bloodstream.
The third type, cholestatic, or obstructive, jaundice, occurs when essentially
normal liver cells are unable to transport bilirubin either through the hepatic-bile
capillary membrane, because of damage in that area, or through the biliary tract,
because of anatomical obstructions such as gallstones or cancer.
In most cases, jaundice is an important symptom of some inherent bodily
disturbance, but aside from the neonatal period the retention of bilirubin itself
does not usually cause any greater damage than skin discoloration that lasts until
the systemic problem is corrected.
Cholestatic jaundice, especially if prolonged, can produce secondary disorders
that may result in the failure of bile salts to reach the intestinal tract.
Bleeding can occur in the intestines because of the absence of bile salts, for
without them the fat-soluble vitamin K cannot be absorbed properly by the body.
Without this vitamin, blood clotting is impaired, so that there is a greater
tendency for bleeding to occur.