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Understanding Human Disease Chapter 21 Liver

Terms in this set (28)

Liver receives blood from two sources
Hepatic Artery: which brings in oxygenated blood from general supply.
Hepatic Portal Vein: brings deoxygenated blood with nutrients from small intestine.
Sinusoids
Small capillary in liver
Functions of Liver
Metabolism: CHO, Protein, Fat
Synthesis of Bile
Detoxification
Storage: Vit. B12, Vit A
Synthesis plasma proteins and clotting factors
Nutritional Functions of Liver
Sugars - stored as glycogen
Gluconeogensesis
Proteins - synthesized as amino acids
Fats - synthesized, packaged into lipoproteins
Formation of ketones,
Formation of bile
Storage of fat soluble vitamins
Functions of Liver - Clearance of Waste Product
Drug and hormone metabolism: biotransformation into water-soluble forms, detoxification or inactivation.
Synthesis of urea
Removal of bilirubin
Alcohol metabolism
Bilirubin metabolism
Liver only organ to remove heme waste products.
Hemoglobin - Heme - Bilirubin: Iron reused, globin chains reused.
Liver conjugates bilirubin: glucoronide, increases solubility.
Secreted in bile, also eliminated in urine.
Metabolism of Drugs
Cytochrome p450: family of enzymes
Elimination of xenobiotics and endogenous compounds.
Jaundice
Often Symptomatic of liver or gallbladder problem.
Pathophysiology of Jaundice
Prehepatic: Overproduction of bilirubin, Unconjugated bilirubin increased.
Hepatic: Metastatic Cancer, Cirrhosis
Posthepatic: Biliary obstruction, conjugated bilirubin increased.
Liver Function Tests
Liver Enzymes:
Aspartate Amiotransferase (AST): liver or muscle problems
Alanine Aminotransferase (ALT): metabolize protein.
Alkaline Phosphatase (AP): Bone disease
Viral Hepatitis
Hepatitis = inflammation of the liver.
Systemic Viral disease primarily affecting liver: Hepatitis A,B,C,D,E
Distinguished by: mode of transmission, carrier state, chronic, vaccine, fulminant
Hepatitis A
HAV
Epidemic Hepatitis
Primarily fecal-oral transmission.
Benign and Self-Limiting
Incubation is about 2-6 weeks.
Most common type in the world.
Fatalities rare, no carrier state.
Vaccine.
Hepatitis B
HBV
Infects hundreds of millions worldwide
Incubation varies from a a few weeks to 6 months.
Transmitted through contact with infected blood, body fluids, shared needles.
Fetus in utero or during vaginal delivery.
Acute and Chronic.
Vaccine Available.
Hepatitis C
Spread primarily by blood-to-blood contact.
80% of hepatitis C cases result in chronic hepatitis.
Risk Factors: Contact with blood at work, unprotected sex, blood transfusion.
No vaccine - mutating RNA virus.
Major cause of chronic liver disease.
Incubation period varies from few weeks to 6 months.
Hepatitis D
Depends on Hepatitis B for replication.
Hepatitis E
Fecal-oral transmission.
Developing countries.
Mild and self-limiting.
Epidemic in India.
Fatty Liver
Fat accumulates in liver secondary to injury.
Common in heavy drinkers and alcoholics.
May be caused by chemicals and solvents.
Impaired liver function but injury is still reversible.
Alcoholic Liver Disease
Refers to a group of structural and functional changes in the liver resulting from excessive alcohol consumption.
Severity depends on amount and duration of alcohol consumption.
3 Stages of progression of Alcoholic liver disease
1. Alcoholic fatty liver: mildest form
2. Alcoholic hepatitis: Causes degenerative changes and necrosis of liver cells.
3. Alcoholic cirrhosis: most advanced, diffuse scarring, disturbed liver function.
Cirrhosis
Irreversible inflammatory Disease that disrupts liver function and structure.
Decreased hepatic function.
Increased Fibrosis.
Causes of Cirrhosis: Alcohol, Hepatitis Virus (B,C,D), Autoimmune Diseases, Biliary Obstruction (cystic fibrosis, gallstones)
Alcoholic Cirrhosis
Final and Irreversible stage of alcoholic liver disease.
Only about 15% of alcoholics develop.
One of the leading causes of liver transplantations in US.
Non-Alcoholic Fatty Liver Disease
2/3 are obese individuals.
Characterized by steatosis (fatty build up), which can lead to steaohepatitis.
Clinical Features of Cirrhosis
Failure to metabolize estrogen and ammonia.
Protein Synthesis failure.
Excretory Failure.
Portal Hypertension.
Hepatic Encephalopathy
Deterioration of brain function characterized by impaired consciousness, confusion, disorientation, and eventually coma: from build up of toxic substances usually excreted by liver.
Toxic products are ammonia from deamination of amino acids, and bacterial decompositions from colonic fecal material.
Precipitating events: conditions that reduce hepatic blood flow or liver functions.
Cholelithiasis
Gallstones in the gallbladder or biliary tree.
Form in gallbladder.
Usually have multiple stones.
50% require surgery.
Usually no symptoms until they begin to move, mid-size stones are worst.
Painful cramps in right-upper quandrant.
Gallstones
Hard, pebble like deposits.
Risk Factors for Gallstones: Increase with age, women more than men, obesity, family history.
Types: cholesterol (yellow), pigmented (dark brown)
Cholecystitis
Most common major complication of gallstones: 90% associated with obstruction of the neck.
Gallbladder is enlarged, tense, and inflamed.
Persistent rather mild RUQ pain to very severe pain.
Liver Neoplasm
Primary: Hepatocellular Carcinoma, complications of chronic hepatitis.
Metastatic: Most liver neoplasm has metastasized to liver from somewhere else (colon, lung, breast)
Poor prognosis.
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