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Krista Chau Walter Gao Sarah Son Kin Wong PHM142 Fall 2014 Instructor: Dr. Jeffrey Henderson.

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Presentation on theme: "Krista Chau Walter Gao Sarah Son Kin Wong PHM142 Fall 2014 Instructor: Dr. Jeffrey Henderson."— Presentation transcript:

1 Krista Chau Walter Gao Sarah Son Kin Wong PHM142 Fall 2014 Instructor: Dr. Jeffrey Henderson

2  Yellow waste product from metabolism of heme  Open chain of tetrapyrrole  Known as bile pigment

3  80% degradation of heme in hemoglobin  20% myoglobin, cytochrome, catalase

4  Oxidative cleavage by heme oxygenase, resulting in bilverdin  Reduction by biliverdin reductase, resulting in unconjugated bilirubin

5  Conjugated bilirubin enters bile and is secreted into the small intestines  Some urobilinogen is reabsorbed into the liver

6  Urobilinogen is converted to uribilin and excreted with urine  Most of the urobilinogen in the intestine is converted to stercobilin and excreted in feces

7

8  Downregulation or inhibition of heme oxygenase and biliverdin reductase

9  Increased production of bilirubin ◦ Acute hemolytic crises causes greater breakdown of heme  Erythropoiesis

10 Oh no! I’m lacking UDP- glucoronosyltransferase (UGT)! Oh no! I’m missing transporters to uptake bilirubin!  Impaired Conjugation Crigler-Najjar Syndrome Gilbert’s Syndrome  Impaired hepatic uptake

11  Liver or hepatocyte transplants  Cytochrome P450 inducers ◦ Phenobarbital  Phototherapy ◦ Wavelengths of nm

12  Rate of secretion or flow of bile is obstructed  Hepatitis or biliary obstructions ◦ Invasive treatments are preferred BILE

13  Fox, S. “Human Physiology.” 12e  Kapitulnik, J. “Bilirubin: An Endogenous Product of Heme Degradation with Both Cytotoxic and Cytoprotective Properties.” Molecular Pharmacology  Leach, T. “Bilirubin Metabolism and Jaundice.” AlmostADoctor metabolism-and-jaundice.  Nazer, H. and J. Katz. “Unconjugated Hyperbilirubinemia.” Medscape  Nelson, D.L., and M.M. Cox. “Principles of Biochemistry.” 5e  Ophardt, C. “Hemoglobin Catabolism and Bilirubin.” Virtual Chembook  Weisiger, R.A., and J. Katz. “Conjguated Hyperbilirubinemia.” Medscape  Voet, D., J.G. Voet, and C.W. Pratt. “Fundamentals of Biochemistry: Life at the Molecular Level.” 4e

14  Bilirubin is a waste product formed from the catabolism of heme, using the enzymes heme oxygenase and biliverdin reductase.  In the liver, unconjugated bilirubin which is insoluble in water is conjugated with glucuronic acid by the enzyme UGT to form the soluble (conjugated) bilirubin.  Bilirubin is converted to microbial enzymes into urobilinogen and oxidized to stercobilin to be excreted in feces.  Urobilinogen can also be reabsorbed from intestines and converted to urobilin to be excreted in urine  Unconjugated hyperbilirubinemia is caused by increased production of bilirubin, impaired conjugation or impaired hepatic uptake  Conjugated hyperbilirubinemia is caused by hepatic or biliary obstructions  Gilbert's syndrome is the most common hereditary cause of hyperbilirubinemia, and is found in up to 5% of the population. It is caused by elevated levels of unconjugated bilirubin in the bloodstream as  a result of reductions in glucuronyltransferase.


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