dr gihan gawish. liver - anatomy and physiology largest organ in the body three basic functions...
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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 bileDr 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
Dr Gihan Gawish
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.Dr Gihan Gawish
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.
Dr Gihan Gawish
BILIRUBIN PRODUCTION
Heme(250 to 400 mg/day)
Heme oxygenase
Biliverdin reductase
Hemoglobin(70 to 80%)
Erythroid cellsHeme proteinsmyoglobin, cytochromes
(20 to 25%)
Biliverdin
Bilirubin
NADPH + H+
NADP+
3 [O]
Fe3+ + CO
apoferritinferritin
indirectunconjugatedpre-hepatic
albumin
Dr Gihan Gawish
Dr Gihan Gawish
BILIRUBIN PROCESSING
albumin-Bilirubin
ligandin
Bilirubin diglucuronide
ER
hepatocyte
UDP-Glucuronyl transferase
albumin
ligandin-Bilirubin
bile (gall bladder)
directconjugatedpost-hepatic
2 UDP-glucuronate
2 UDP
Dr Gihan Gawish
BILIRUBIN EXCRETION
Bilirubin diglucuronide
Intrahepatic urobilinogen
cycle
Stercobilinogen
Bacterial enzymes
Bilirubin
Bacterial enzyme2 glucuronate
Bacterial enzyme
Urobilinogen
8H
liver
Urobilinkidneys
urine
Stercobilin feces
kidneys
intestines
DEGRADATION OF HEME TO BILIRUBIN
P450 cytochrome
75% is derived from RBCs
In normal adults this results in a daily load of 250-300 mg of bilirubin
Normal plasma concentrations are less then 1 mg/dL
Hydrophobic – transported by albumin to the liver for further metabolism prior to its excretion
“unconjugated” bilirubin
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
Dr Gihan GawishDr Gihan Gawish
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.
HYPERBILIRUBINEMIA
Increased plasma concentrations of bilirubin (> 3 mg/dL) occurs when there is an imbalance between its production
and excretion
Recognized clinically as jaundice
Dr Gihan GawishDr Gihan Gawish
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. Dr Gihan Gawish
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
Dr Gihan Gawish
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
Dr Gihan Gawish
Lab Tests Elevated Alkaline
phosphatase
Elevated with bone and liver disorders
Elevated SGOT/AST
Elevated SGPT/ALT
Elevated serum globulin
Elevated LDH
Decreased albumin
Increased prothrombin time
Blood ammonia level • Increased due to
decreased metabolism of
ammonia to urea by the liver
Dr Gihan Gawish