Liver, Gallbladder, and Pancreas Anatomy

Liver, Gallbladder, and Pancreas

• Liver, gallbladder, and pancreas are accessory organs for the small intestine.
• Liver: Produces bile, a fat emulsifier.
• Gallbladder: Stores bile.
• Pancreas: Provides digestive enzymes and bicarbonate to neutralize stomach acid.

Liver Gross Anatomy

• Largest gland (around 3 lbs).
• Four lobes: right, left, caudate, and quadrate.
• Falciform ligament divides the larger right and smaller left lobes, suspending liver from the diaphragm and abdominal wall.
• Round ligament, a remnant of the umbilical vein, is along the free edge of the falciform ligament.
• Lesser omentum attaches the liver to the stomach.
• Blood enters through the hepatic artery and hepatic portal vein at the porta hepatis.
• Bile ducts include the common hepatic duct, cystic duct, and the bile duct.

Liver Microscopic Anatomy

• Liver lobules: hexagonal functional units composed of hepatocytes (liver cells) filtering and processing nutrient-rich blood.
• Central vein in the longitudinal axis of lobule.
• Portal triad in each corner: hepatic artery branch (oxygen), hepatic portal vein branch (nutrient blood), and bile duct.
• Liver sinusoids: leaky capillaries between hepatocyte plates.
• Blood from hepatic portal vein and hepatic artery proper flows through sinusoids and to central vein.
• Stellate macrophages remove debris and old red blood cells.
• Hepatocytes have increased rough and smooth ER, Golgi apparatus, peroxisomes, and mitochondria. 
• Hepatocytes produce approximately 900 ml of bile daily, process blood nutrients (glucose storage as glycogen, plasma protein production), store fat-soluble vitamins, and detoxify (e.g., ammonia to urea).

Bile

• Yellow-green, alkaline solution containing:

  • Bile salts (cholesterol derivatives), for fat emulsification and absorption.
  • Bilirubin (pigment from heme), broken down in intestine to stercobilin (brown feces).
  • Cholesterol, triglycerides, phospholipids, and electrolytes.

• Enterohepatic circulation: bile salts reabsorbed in ileum, returned to liver via hepatic portal blood, and recycled (about 95%).

Gallbladder

• Thin-walled muscular sac on liver's ventral surface.
• Stores and concentrates bile by absorbing water and ions.
• Contains folds to expand during filling.
• Muscular contractions release bile via cystic duct into bile duct.

Liver and Gallbladder Imbalances

• Hepatitis: liver inflammation (viral, drug toxicity, obesity).
• Cirrhosis: chronic inflammation (hepatitis, alcohol), progressive scar tissue regeneration faster than hepatocytes.
• Liver transplants are successful but livers are scarce; livers can regenerate to full size in 6–12 months after 80% removal.
• Gallstones: from excess cholesterol or insufficient bile salts.
• Obstructive jaundice: blockage of bile flow, leading to buildup of bile salts/pigments and yellow skin.
• Gallstone treatment: drug therapy, ultrasound vibrations (lithotripsy), laser vaporization, or surgery.