Liver structure and function
Liver is the largest organ
Consist of two lobes; right and left
Functions :
 - Carbohydrate, protein, and fat metabolism
    * glycogenesis, glycogenolysis, gluconeogenesis
    * protein synthesis; albumin, globulin
Albumin   oncotic pressure, carrier for drugs
Globulin  coagulation factors
Fatty acid are taken up by the liver; cholesterol synthesis; bile salt synthesis
Drug metabolism
Enterohepatic circulation

Evaluation of liver function
Aminotransferases (Transaminases)
    - hepatocellular damage
    - alanine aminotransferase (ALT, SGPT) : primarily in the liver
    - aspartate aminotransferase (AST, SGOT); present in many tissues; heart, skeletal muscle, kidney, brain
Alkaline phosphatase
    - bone, intestine, liver, placenta
    - impaired biliary tract function
Gamma-glutamyl transferase (GGT)
    - widely in body tissues
    - increased level: biliary tract disease
Serum protein
    - liver injury may lead to decreased blood levels of albumin, prothrombin, fibrinogen
    - not specific for liver disease
    * Albumin and globulin : long half-life
    * Prothrombin time : shorter half-life

Jaundice
Yellow or greenish pigmentation of the skin caused by hyperbilirubinemia (plasma bilirubin concentrations above 2-2.5 mg/dL)
Unconjugated bilirubin (UCB) = indirect bilirubin
Conjugated bilirubin (CB) = direct bilirubin
Derangements of bilirubin metabolism may occur through any of four mechanisms :
    - overproduction : hemolysis
    - decreased hepatic uptake
    - decreased hepatic conjugation
    - decreased excretion of bilirubin into bile (due to intrahepatic dysfunction or extrahepatic mechanical obstruction)

Hepatocellular failure
Acute liver failure
- Causes :
1. Massive liver cell necrosis due to viral hepatitis (HBV or HCV), some drugs (e.g., halothane, isoniazid, acetaminophen), toxic chemicals (e.g., chloroform, mushroom poisoning)
Acute liver failure
2. Acute fatty change Reye’s syndrome, fatty liver of pregnancy, tetracycline
Chronic liver failure
- Most common causes is cirrhosis, chronic active hepatitis

Hepatocellular failure
Characteristic physiological changes of liver failure include
1. Jaundice
2. Coagulopathy due to malabsorption of vitamin K and reduced synthesis of clotting factors II, VII, IX, and X
3. Changes in neurologic status : hepatic encephalopathy
4. Hypogonadism and gynecomastia due to imabalance of androgen-estrogen levels
5. Palmar erythema
6. Spider angiomatas of the skin
7. Fetor hepaticus
8. Ascites
9. Portal hypertension

Cirrhosis
Irreversible inflammatory disease that disrupts liver structure and function disorganization of hepatic tissues is caused by diffuse fibrosis and nodular regeneration
Liver may be larger or smaller than normal, and usually it is firm or hard when palpatated

Physiology of biliary tract
Gallbladder : a saclike organ : store and concentrate bile between meals
Bile : alkaline, bitter-tasting, yellow green fluid that contains
    * bile salts (conjugated bile acids), conjugate with amino acids (glycine or taurine) in the liver      more water soluble : intestinal emulsification, absorption of fats
     * cholesterol, bilirubin (a pigment), electrolytes, waters....

Share Medical Presentations