Makindo Medical Notes

Related Subjects: |Anatomy of the Ear |Anatomy of the Oesophagus |Anatomy of the Diaphragm |Anatomy of Large Bowel |Anatomy of Small Bowel |Anatomy of the Biliary system |Anatomy of the Eye |Anatomy of the Larynx |Anatomy of the Ear |Anatomy of Male Genitalia

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