Anatomy of the Biliary system
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The gallbladder and biliary system store and transport bile, which is essential for fat digestion.
The gallbladder is a pear-shaped sac beneath the liver in the right upper quadrant (RUQ).
🧩 Gallbladder Anatomy
- Location: Inferior surface of liver (gallbladder fossa), RUQ.
- Size: 7–10 cm, ~50 mL bile capacity.
- Parts:
– Fundus: Rounded distal end.
– Body: Main storage chamber.
– Neck: Narrow portion → cystic duct.
📍 Biliary Anatomy
- Right + Left Hepatic Ducts: Drain liver bile → join as common hepatic duct.
- Cystic Duct: Connects gallbladder neck → common hepatic duct.
- Common Bile Duct: Union of hepatic + cystic ducts → drains into duodenum.
- Ampulla of Vater: Junction of common bile duct + pancreatic duct.
- Sphincter of Oddi: Controls bile + pancreatic juice entry → prevents reflux.
⚙️ Physiology
Main roles: store, concentrate, and release bile → emulsifies fats for absorption. 🥓
🧪 Functions
- Storage: Between meals, bile flows into gallbladder for storage.
- Concentration: Water + electrolytes reabsorbed → concentrated bile salts.
- Secretion: After fatty meal, CCK triggers contraction → bile expelled into duodenum.
💧 Composition of Bile
- Bile salts: From cholesterol → fat emulsification.
- Bilirubin: Hb breakdown product → gives yellow-green colour.
- Cholesterol: Excreted in bile; excess → gallstones.
- Water & electrolytes: Facilitate transport.
➡️ Bile Flow
- Production: Continuous in liver.
- Storage: Gallbladder via cystic duct.
- Release: Fatty meal → CCK → gallbladder contraction + sphincter of Oddi relaxation → duodenum.
🔄 Regulation
- CCK: Gallbladder contraction + Oddi relaxation.
- Secretin: ↑ hepatic bile secretion (esp. bicarbonate-rich bile).
- Vagus nerve: Parasympathetic → mild gallbladder contraction (cephalic phase).
🩸 Blood Supply
- Artery: Cystic artery (branch of right hepatic artery).
- Veins: Cystic veins → portal system.
🧠 Nerve Supply
- Sympathetic: ↓ bile secretion, inhibits contraction.
- Parasympathetic (vagus): Stimulates contraction & bile release.
⚠️ Clinical Relevance
- 🪨 Cholelithiasis (Gallstones): Precipitated cholesterol/bilirubin → RUQ pain.
🧠 Risk factors: “5 Fs” → Female, Forty, Fertile, Fat, Fair.
- 🔥 Cholecystitis: Inflammation (often due to obstructed cystic duct).
– Murphy’s sign positive.
- ⏳ Biliary colic: Temporary cystic duct obstruction → colicky postprandial pain.
- 🚧 Choledocholithiasis: Stone in common bile duct → jaundice ± pancreatitis.
- 🦠 Cholangitis: Bile duct infection (Charcot’s triad: fever, jaundice, RUQ pain) → emergency.
- 🎗️ Gallbladder carcinoma: Rare, linked to chronic inflammation + gallstones.
📊 Quick Revision Table
| Structure |
Function |
Clinical Note |
| Gallbladder |
Stores & concentrates bile |
Cholelithiasis, cholecystitis |
| Cystic duct |
Connects gallbladder to biliary tree |
Biliary colic if obstructed |
| Common bile duct |
Carries bile to duodenum |
Choledocholithiasis, obstructive jaundice |
| Sphincter of Oddi |
Controls bile/pancreatic juice flow |
Blockage → cholangitis, pancreatitis |
| Ampulla of Vater |
Entry point to duodenum |
Obstruction → gallstone pancreatitis |
