Lecture on the Liver - Chapter 38

Portal Triad and Liver Structure

• Functional Unit: Hexagonal prism.
  • Vertex: Contains portal triads.
    • Components of Portal Triads:
      • Hepatic artery
      • Portal vein
      • Bile duct
  • Central Vein: Located at the center of the hexagon.
• Function:
  • Bile from bile canaliculi flows into the bile duct.
  • Sinusoids: Large venous structures containing Kupfer cells (liver-specific macrophages).

Liver Functions

Digestive Functions

• Produces bile for emulsification of fats (not digestion).
• Processes and stores fats, carbohydrates, and proteins.
• Processes and stores vitamins and minerals.

Endocrine Functions

• Regulates carbohydrate, fat, and protein metabolism.
• Metabolizes glucocorticoids, mineralocorticoids, and sex hormones.
• Cholesterol (precursor of steroid hormones) synthesis occurs in the liver.

Hematologic Functions

• Stores blood and decommissions red blood cells (RBCs).
• Converts heme to bilirubin, eventually forming bile.
• Capable of producing RBCs in certain disease states.
• Produces blood clotting factors.

Excretory Functions

• Excretes bile pigments and cholesterol.
• Detoxifies drugs and foreign substances.
• Synthesizes urea from amino acids (urea cycle).

Liver Damage and Hepatocellular Failure

• Common Presentation: Jaundice due to bilirubin accumulation.
• Other Symptoms:
  • Muscle wasting
  • Ascites (fluid accumulation in abdomen due to portal hypertension)
  • Fat-soluble vitamin metabolism issues (A, D, E, K)
  • Osteomalacia from Vitamin D deficiency
  • Clotting issues from Vitamin K deficiency
  • Glucose level dysregulation (hyperglycemia or hypoglycemia)
  • Edema due to lack of albumin production

Hormonal Processing Issues

• Men: Elevated estrogen can cause gynecomastia, impotence, testicular atrophy, and feminine hair distribution.
• Women: Irregular menstrual cycle.
• Symptoms: Palmar erythema and spider telangiectasia.

Metabolic Disorders

• Dyslipidemias: Elevated triglycerides due to inadequate lipoprotein processing.
• Urea Production Failure: Leads to ammonium build-up causing hepatic encephalopathy, affecting neuronal function.