Disorders of Hepatobiliary and Exocrine Pancreas Function

Liver Structure, Blood Flow, and Accessory Organs

The liver is a vital organ with complex structure and functions, supported by accessory organs such as the gallbladder and pancreas. Understanding its anatomy and blood flow is essential for recognizing disease processes.

• Liver Lobular Structure:

  • The liver is the largest organ in the abdomen (about 3 lb in adults), located under the diaphragm in the right upper abdomen.

  • It is divided into two large lobes (right and left) and two small lobes (caudate and quadrate).

• Liver Blood Flow:

  • Hepatic portal vein: Brings nutrient-rich blood from the digestive tract and abdominal organs.

  • Hepatic artery: Supplies oxygenated blood to the liver.

  • Hepatic veins: Valveless veins that drain blood from the liver into the inferior vena cava.

• Accessory Organs:

  • Gallbladder: Stores and releases bile to help digest fats.

  • Exocrine pancreas: Produces digestive enzymes that flow into the small intestine.

Functions of the Liver and Pancreas

The liver and pancreas perform essential metabolic, synthetic, and excretory functions necessary for digestion and homeostasis.

• Liver Functions:

  • Produces bile salts to help digest fats.

  • Metabolism: Breaks down carbohydrates, fats, and proteins.

  • Stores vitamins and minerals.

  • Detoxifies the blood: Removes drugs, hormones, and bacteria.

  • Processes bilirubin: Eliminates waste from red blood cells.

  • Synthesizes important proteins: Glucose, plasma proteins, clotting factors.

  • Metabolizes steroid hormones.

• Bile Production:

  • The liver produces 500-600 mL of yellow-green bile daily.

  • Cholestasis: Reduced bile flow leads to less water, bilirubin, and bile acids excreted.

• Pancreas Functions:

  • Exocrine role: Produces enzymes for digestion.

  • Endocrine role: Makes insulin and glucagon to control blood sugar.

Jaundice: Causes and Categories

Jaundice is a yellow discoloration of the skin and eyes due to elevated bilirubin levels. It can result from various disruptions in bilirubin metabolism or excretion.

• Causes of Jaundice:

  • High destruction of red blood cells (↑ bilirubin).

  • Liver cannot take up bilirubin properly.

  • Liver cannot conjugate bilirubin for elimination.

  • Obstructed bile flow in the liver or bile ducts.

Assessments of Liver Function

Several laboratory and imaging tests are used to evaluate liver function and detect injury or disease.

• Serum aminotransferase levels (ALT, AST): Indicate liver cell injury.

• Serum bilirubin, Gamma-Glutamyl Transferase (GGT), alkaline phosphatase: Measure liver’s ability to excrete bile.

• Ultrasound, CT, MRI: Assess liver structure.

• Angiography: Examines blood flow in hepatic/portal circulation.

• Liver biopsy: Provides tissue sample for microscopic examination.

Pathologic Conditions Affecting the Hepatobiliary System

Various factors can damage the liver and biliary system, leading to acute or chronic disease.

• Drugs and toxins: Can damage liver cells.

• Infections & inflammation: Cause liver injury.

• Immune responses: The body attacks its own liver tissue (autoimmune).

• Metabolic disorders: Disrupt normal liver function.

• Neoplasms (tumors): Abnormal growths in the liver or biliary system.

Factors Contributing to Susceptibility to Drug-Induced Liver Disease

Drug-induced liver injury is influenced by genetic, physiological, and environmental factors.

• Genetics: Some individuals are more prone to liver damage.

• Age: Younger vs. older patients react differently.

• Pre-existing liver disease: Increases risk of damage.

• Alcohol use: Worsens drug effects on the liver.

• Polypharmacy: Taking multiple drugs increases the chance of harmful interactions.

Types of Drug-Induced Liver Disease

• Hepatotoxic injury: Predictable, dose-related liver cell damage.

• Idiosyncratic reactions: Unpredictable, occur only in some people.

• Cholestatic reactions: Blockage of bile flow due to drugs.

• Chronic hepatitis: Long-term liver inflammation from repeated drug exposure.