pathobiochemistry of liver. portal vein hepatic artery bile duct sinusoids bile canaliculi central...
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Pathobiochemistry of liver
portal vein
hepatic artery
bile duct
sinusoids
bile canaliculi
central vein
LIVER STRUCTURELIVER STRUCTURE
LIVER FUNCTIONSLIVER FUNCTIONS
•Distribution of nutrients•All types of metabolism (protein, lipid, carbohydrate, vitamin, mineral)•Excretory (bile acids, urea synthesis)•Destruction of toxic substances•Depot of iron, vitamins
METABOLISM OF CARBS IN METABOLISM OF CARBS IN LIVERLIVER
glycolisis metabolism of fructose and galactose gluconeogenesis release of glucose into blood (maintain the stable glucose concentration in blood) conversion of pyruvate into acetyl CoA tricarboxylic acid cycle pentose phosphate pathway glycogenolysis, glycogenogenesis
METABOLISM OF LIPIDS IN METABOLISM OF LIPIDS IN LIVERLIVER
synthesis of lipoproteins synthesis of triacylglyserols synthesis of phospholipids synthesis of fatty acids, elongation of fatty acids chain, desaturation synthesis of cholesterol ketone bodies formation lipolysis fatty acids oxidation
METABOLISM OF PROTEINS IN METABOLISM OF PROTEINS IN LIVERLIVER
protein synthesis, including blood plasma proteins protein decomposition; urea synthesis conversion of proteins into carbs and lipids interconversion of aminoacids conversion of proteins into low molecular weight nitrogen containing substances
• Formation of active form of vitamin D
• Formation of vitamin A from carotins
• Depo of cyanocobalamine and folic acid
• Depo of vitamin E• Phosphorilation of vitamins B,
formation of coenzyme forms
VITAMIN METABOLISM IN LIVER
DETOXIFICATION OF TOXIC DETOXIFICATION OF TOXIC SUBSTANCES IN LIVERSUBSTANCES IN LIVER
Phase I and phase II.
Phase I: hydrolysis, reduction, oxidation.
These reactions introduce functional group (—OH, —NH2, —SH, or —COOH) and usually result in a little increase of hydrophylic properties
Phase II includes: glucuronation, sulfation, acetylation, methylation, conjugation with glutathione, conjugation with aminoacids (glycin, taurin, glutamic acid)
Phase II results in the marked increase of hydrophylic properties of xenobiotic.
REACTION ENZYME LOCALIZATION
PHASE I
Hydrolysis
Reduction
Oxidation
EsterasePeptidase Epoxide hydrolase
Azo- and nitro-reduction Carbonyl reductionDisulfide reductionSulfoxide reduction
Alcohol dehydrogenaseAldehyde dehydrogenaseAldehyde oxidaseXanthine oxidaseMonoamine oxidaseDiamine oxidaseFlavin-monooxygenasesCytochrome P450
Microsomes, cytosol, lysosomes, blood lysosomes Microsomes, cytosol
Microflora, microsomes, cytosolCytosol, blood, microsomesCytosolCytosol
CytosolMitochondria, cytosolCytosolCytosolMitochondriaCytosolMicrosomesMicrosomes
PHASE II
Glucuronide conjugationSulfate conjugationGlutathione conjugationAmino acid conjugationAcetylationMethylation
MicrosomesCytosol, microsomesCytosolMitochondria, cytosolMitochondria, microsomesCytosol, microsomes, blood
General ways of xenobiotics biotransformation and their localization in cell
PHASE I
Hydrolysis
Esterases (carboxyesterases, cholinesterases, phosphatases) Peptidases
ReductionMetals and xenobiotics containing aldehyde, keto, disulfide, alkyn, azo, or nitro group are often reduced
Reducing agents:Reduced glutathione, FADH2, FMN,NADH NADPH.
OxidationAlcohol dehydrogenase
Aldehyde dehydrogenase
Oxidizes aldehydes to carbonic acids
Xanthine dehydrogenase-Xanthine oxidase
Monoaminooxidase
Oxidative deamination of amines (serotonin) and many xenobiotics
Cytochrom P450
The highest concentration – in endoplasmic reticulum of hepatocytes (microsomes).
Hem containing protein.
Catalyzes monooxigenation of oxygen atom into substrate; another oxygen atom is reduced to water
Electrons are transferred from NADPH to cytochrome P450 through flavoprotein NADPH-cytochrome P450 reductase.
SCHEME OF MONOOXYGENASE SYSTEM
The example of reaction that is catalyzed by cytochrome P450: hydroxylation of aliphatic carbon
The example of reaction that is catalyzed by cytochrome P450: hydroxylation of aromatic carbon
JAUNDICES
NORMAL METABOLISM OF BILE PIGMENTS
CELLS OF RESIndirect bilirubin
NADP+
NADPH2
Biliverdin reductase
Biliverdin
Iron
Globin
Verdoglobin
NADP+
Hemoxi-genase
NADPH2
Hemoglobin ERYTHROCYTES
KIDNEYS
Stercobilinogen
URINE
Stercobilin
Indirect bilirubin 1,7-20,5 mkmol/l
albumin
albumin
Indirect bilirubin
UDP-glucoronil-transferase
Direct bilirubin 0.8-4.3 mkmol/l
BLOOD
LIVER
Bilirubin mono-glucoronid, 20 %
Bilirubin di-glucoronid, 80 %
Dipyrols
-glucoro-nidase
Glucoronic acid
Direct bilirubin
BILE
INTESTINE
Mesobilirubin
Mesobilirubin (urobilinogen)
Stercobilinogen
Stercobilin
STOOL
METABOLISM OF BILE PIGMENTS IN HEMOLYTIC JAUNDICE
CELLS OF RES
Indirect bilirubin
Indirect bilirubin
albumin
albumin
Indirect bilirubin
Biliverdin reductase
UDP-glucoronil-transferase
Direct bilirubin
NADP+
NADPH2
Biliverdin
Iron
Globin
Verdoglobin
NADP+
NADPH2
Hemoglobin
Hemoxi- genase
BLOOD
LIVER
Bilirubin mono-glucoronid, 20 %
Bilirubin diglucoronid, 80 %
-glucoro- nidase
Glucoronic acid
Direct bilirubin
BILE
ERYTHROCYTES
KIDNEYS
INTESTINE
STOOL
Stool hypercholic
URINEUrine dark
Mesobilirubin
Mesobilinogen (urobilinogen)
Stercobilinogen
Stercobilin
Stercobilinogen
StercobilinUrobilin
METABOLISM OF BILE PIGMENTS IN HEPATIC JAUNDICE
CELLS OF RES
Indirect bilirubin
Indirect bilirubin
albumin
albumin
Indirect bilirubin
Biliverdin reductase
UDP-glucoronil-transferase
Direct bilirubin
NADP+
NADPH2
Biliverdin
Iron
Globin
Verdoglobin
NADP+
NADPH2
Hemoglobin
Hemoxi- genase
BLOOD
LIVER
Bilirubin mono-glucoronid, 20 %
Bilirubin diglucoronid, 80 %
-glucoro- nidase
Glucoronic acid
Direct bilirubin
BILE
ERYTHROCYTES
KIDNEYS
Urobilinogen INTESTINE
STOOL
Stool hypocholic
URINEUrine dark
Stercobi-linogen
StercobilinBilirubinUrobilin
Mesobilirubin
Mesobilinogen (urobilinogen)
Stercobilinogen
Stercobilin
METABOLISM OF BILE PIGMENTS IN OBSTRUCTIVE JAUNDICE
CELLS OF RESIndirect bilirubin
Indirect bilirubin
albumin
albumin
Indirect bilirubin
Biliverdin reductase
UDP-glucoronil-transferase
Direct bilirubin
NADP+
NADPH2
Biliverdin
Iron
Globin
Verdoglobin
NADP+
NADPH2
Hemoglobin
Hemoxi- genase
BLOOD
LIVER
Bilirubin mono-glucoronid, 20 %
Bilirubin diglucoronid, 80 %
Bile acids
-glucoro- nidase
Glucoronic acid
Direct bilirubin
BILE
Direct bilirubin
ERYTHROCYTES
KIDNEYS
Direct bilirubinINTESTINE
STOOL
Stool acholic, steatorhea
URINE Direct bilirubin Bile acids
Urine dark, foaming
Etiology and pathogenesis of liver insufficiency
• Infectious agents (hepatitis B virus, tuberculosis bacillus, helmints)• Hepatotropic poison (drugs - tetracycline, sulfonamides, industrial poisons - carbon tetrachloride, arsenic, chloroform, vegetable poisons - aflatoxin, muscarine)• Physical impacts (ionizing radiation)• Biological drugs (vaccines, serums)• Violation of blood circulation (thrombosis, embolism, venous congestion)• Endocrine pathology (diabetes mellitus, hyperthyroidism)• Tumors• Hereditary ensymopathy
Causes of Liver Failure
Consequences of Liver Failure
Fibrosis and Cirrhosis of the Liver
Fibrosis and Cirrhosis of the Liver
Clinical syndromes in liver injury
Lack of liver disorders manifested its functions lesion:• metabolic (involved in carbohydrate, fat, protein metabolism, metabolism of vitamins, hormones, biologically active substances)• protection (phagocytic and antitoxic)• digestive and excretory (the formation and release of bile)• hemodynamic (involved in maintaining systemic circulation).
Cholelithiasis: Abnormal Cholesterol to Bile Salt Ratio
Clinical syndromes of jaundice• Acholia associated with non-receipt of bile in the
intestine due to violations of the formation and outflow of bile. Acholia manifested disorders of digestion and absorption of fats, hypovitaminosis A, E, K, decreased intake of unsaturated fatty acids of phospholipids to build cell membranes, intestinal motility violation, increasing decay and fermentation.
• Dyscholia - violation of the physical-chemical properties of bile, causing it acquires the ability to form stones (due to genetic predisposition, poor nutrition, metabolic disorders, infectious-inflammatory processes, cholestasis).
Cholelithiasis: Abnormal Cholesterol to Bile Salt Ratio
Etiology and pathogenesis of jaundice
• Jaundice - a syndrome caused by an increase in blood bilirubin (hemolytic, parenchymal, mechanical).
• In hemolytic jaundice due to destruction of a large number of red blood cells accumulate indirect, protein bound bilirubin.
• When parenchymal jaundice disturbed capture, and excretion of bilirubin in hepatocytes due to their injuries.
• In mechanical jaundice occurs outflow obstruction of bile, compression of biliary tract tumor or scar, closing within a stone, worms, thick bile.
Mechanisms and Consequences of Cholestasis
Methods of experimental study of liver pathology
• hepatic-cell failure simulating full or partial removal of the liver, the introduction of poisons (carbon tetrachloride, chloroform, trinitrotoluene);• cholestatic model obtained by squising bile ducts by ligature;• hepatic vascular insufficiency simulating by overlapping portocaval anastomosis, ligation portal vein, hepatic vein, hepatic artery.