Liver, Gallbladder, and Pancreas Anatomy Quiz

Liver, Gallbladder, and Pancreas

• The liver, gallbladder, and pancreas are accessory organs aiding the small intestine in digestion.
• Liver: Produces bile, essential for fat emulsification.
• Gallbladder: Stores bile.
• Pancreas: Provides digestive enzymes and bicarbonate to neutralize stomach acid.

Liver Gross Anatomy

• Largest gland in the body (~3 lbs).
• Four primary lobes: right, left, caudate, and quadrate.
• Falciform ligament: Separates right and left lobes, anchors liver to diaphragm and abdominal wall.
• Round ligament: Remnant of fetal umbilical vein.
• Lesser omentum: Anchors liver to the stomach.
• Blood supply through hepatic artery and hepatic portal vein, entering at porta hepatis.
• Bile ducts: Common hepatic duct carries bile away from the liver and joins the cystic duct (from gallbladder) to form the bile duct.

Liver Microscopic Anatomy

• Liver lobules: Hexagonal structural and functional units.
• Hepatocytes (liver cells): Filter and process nutrient-rich blood within plates.
• Central vein: Located along the longitudinal axis of the lobule.
• Portal triad: Located in each corner of the lobule, comprising:
  • Hepatic artery branch: Supplies oxygen.
  • Hepatic portal vein branch: Brings nutrient-rich blood from intestine.
  • Bile duct: Receives bile from bile canaliculi.
• Liver sinusoids: Leaky capillaries between hepatic plates. Blood from the hepatic portal vein and hepatic artery percolates through sinusoids, emptying into the central vein.
• Stellate macrophages: Remove debris and old red blood cells in liver sinusoids.
• Hepatocytes: Extensive rough and smooth ER, Golgi apparatus, peroxisomes, and mitochondria. Functions include bile production (~900 ml/day), nutrient processing (e.g., glucose storage as glycogen, plasma protein synthesis), vitamin storage (fat-soluble), and detoxification (e.g., ammonia to urea).

Bile

• Yellow-green, alkaline solution, composed of:
  • Bile salts: Cholesterol derivatives, emulsify and absorb fats.
  • Bilirubin: Pigment from heme, broken down by bacteria in intestines to stercobilin (gives feces brown color).
  • Cholesterol, triglycerides, phospholipids, and electrolytes.
• Enterohepatic circulation: Recycles bile salts.
  • Bile salts are reabsorbed in the ileum and returned to the liver via hepatic portal blood. About 95% of bile salts are recycled.

Gallbladder

• Thin-walled muscular sac on liver's ventral surface.
• Stores and concentrates bile by absorbing water and ions.
• Honeycomb folds for expansion.
• Muscular contractions release bile via cystic duct, which flows into the bile duct.

Liver and Gallbladder Imbalances

• Liver:
  • Hepatitis: Inflammation (viral, drug toxicity, obesity).
  • Cirrhosis: Chronic inflammation (from chronic hepatitis or alcoholism), progressive scarring (connective tissue regenerates faster than hepatocytes). Liver transplants are used but organs are rare. The liver can regenerate to full size within 6-12 months after 80% removal.
• Gallbladder:
  • Gallstones: Too much cholesterol or too few bile salts, obstruct bile flow, painful when gallbladder contracts against crystals.
  • Obstructive jaundice: Blocked bile flow causes bile salts and pigments to build up in blood, resulting in yellow skin. Factors include liver failure.
  • Treatment options: Crystal-dissolving drugs, ultrasound vibrations (lithotripsy), laser vaporization, or surgery.