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
Dr Gihan Gawish