Transcript Liver
Dr Gihan Gawish
Liver - Anatomy and Physiology
Largest organ in the body
Three basic functions
• Metabolic
• Secretory
• Vascular
Major function
• Excretion of waste products from
bloodstream by excretion into bile
Dr Gihan Gawish
Liver - Anatomy and Physiology
Location
• Upper right quadrant
• Four lobes made up of hepatocytes
• phagocytic cells
Blood supply
• One major vein - portal vein
• One major artery - hepatic
Dr Gihan Gawish
Liver - Anatomy and Physiology
Functions of liver
• Blood glucose concentration
• Protein metabolism
• Fat metabolism
• Storage functions
• Drug metabolism
• Ammonia conversion
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Metabolic Profile of the Liver
The primary function of the liver is to regulate the
metabolism.
It metabolizes the intake of carbohydrates, fats, and
proteins.
It accomplishes this function by working closely with
other systems such as lymphatic system, circulatory
system, as and endocrine system.
In order for the liver to metabolize the fats,
carbohydrates, and proteins, it must be healthy and free
of any diseases.
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Bile Production
Liver produces and secretes a product called bile.
This is what makes it possible for metabolize the intake of
fats, proteins, and carbohydrates.
This fluid is a very important presence in the body due to
the fact that it aids in the elimination of contaminants in
the body, such as drugs.
The bile system is also responsible for re-circulating red
blood cells.
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BILIRUBIN PRODUCTION
Heme proteins
myoglobin, cytochromes
(20 to 25%)
Hemoglobin
(70 to 80%)
Erythroid cells
Heme
ferritin
apoferritin
(250 to 400 mg/day)
3 [O]
Heme oxygenase
3+
Fe + CO
Biliverdin
NADPH + H+
Biliverdin reductase
NADP+
Bilirubin
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albumin
indirect
unconjugated
pre-hepatic
BILIRUBIN PROCESSING
albumin-Bilirubin
albumin
hepatocyte
ligandin
ligandin-Bilirubin
2 UDP-glucuronate
ER
UDP-Glucuronyl
transferase
2 UDP
Bilirubin diglucuronide
bile (gall bladder)
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direct
conjugated
post-hepatic
BILIRUBIN EXCRETION
Bilirubin diglucuronide
2 glucuronate
liver
Bacterial enzyme
Intrahepatic
urobilinogen cycle
Bilirubin
8H
Bacterial enzyme
kidneys
intestines
Urobilinogen
Urobilin
urine
Stercobilin
feces
kidneys
Bacterial enzymes
Stercobilinogen
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DEGRADATION OF HEME TO BILIRUBIN
75% is derived from RBCs
P450 cytochrome
In normal adults this
results in a daily load of
250-300 mg of bilirubin
Normal plasma
concentrations are less then
1 mg/dL
“unconjugated” bilirubin
Hydrophobic – transported
by albumin to the liver for
further metabolism prior to
its excretion
NORMAL BILIRUBIN
METABOLISM
Uptake of bilirubin by the liver is mediated by
a carrier protein (receptor)
Uptake may be competitively inhibited by
other organic anions
On the smooth ER, bilirubin is conjugated with
glucoronic acid, xylose, or ribose
Glucoronic acid is the major conjugate catalyzed by UDP glucuronyl tranferase
“Conjugated” bilirubin is water soluble and is
secreted by the hepatocytes into the biliary
canaliculi
Converted to stercobilinogen (urobilinogen)
(colorless) by bacteria in the gut
Oxidized to stercobilin which is colored
Excreted in feces
Some stercobilin may be re-adsorbed by the
gut and re-excreted by either the liver or
kidney
Failure to Produce Bile
It is possible for a type of liver disease to cause the liver to
stop the secretion of bile.
When this happens, the liver loses the capability to
metabolize the fats, carbohydrate, and proteins.
The only way fats can be absorbed into your blood system is
if bile is present.
This is why it would be impossible for the body to absorb the
fat-soluble vitamins without bile.
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HYPERBILIRUBINEMIA
Increased
plasma
concentrations
of
bilirubin (> 3 mg/dL) occurs when there is an
imbalance between its production and
excretion
Recognized clinically as jaundice
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Diagnoses of Jaundice
Red Blood Cell System
Another important function the liver performs
is that it cleanses the body from the damaged,
or old, red blood cells.
The liver will also store iron in your body, as
well as breakdown hemoglobin.
This is the reason why many people who suffer
from liver disease may suffer from anemia.
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Hepatitis
Inflammation of the liver
Viral hepatitis is the most common type
A, B, C, D and E
Noninfectious hepatitis may be caused by drugs
and chemicals
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Hepatitis – Clinical
Manifestations
Preicteric or Prodromal phase
• Precedes jaundice
• Lasts 1 – 21 days
• Maximal infectivity for hepatitis A
• Symptoms
Anorexia, right upper quadrant pain,
constipation or diarrhea, malaise, fever,
headache, arthralgias, weight loss
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Lab Tests
Elevated Alkaline phosphatase
Decreased albumin
Elevated with bone and liver
Increased prothrombin
Elevated SGOT/AST
Blood ammonia level
disorders
Elevated SGPT/ALT
Elevated serum globulin
time
•
Increased
due
to
decreased metabolism of
ammonia to urea by the
liver
Elevated LDH
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