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Biliary Histophysiology & Pathology, Fasting State / Closed Sphincter,…
Biliary Histophysiology & Pathology
Transepithelial Concentration Mechanism In The Gallbladder
Gallbladder Epithelial Absorption
Biliary Lumen (Hepatic Bile: Water + Salts)
Apical Microvilli (Simple Columnar Epithelium)
Basolateral Active Na⁺ Pump
Pumps Na⁺ into the lateral intercellular spaces
Dilated Intercellular Spaces
Basal Capillary Bed (Drains water & electrolytes)
Concentrated Bile (5–10x concentration factor)
Passive Water Movement by Osmosis
Follows solute gradient into spaces
Ductal Flow Control & Emulsification Physiology
Neurohumoral Regulation
Parasympathetic (Vagal) → Augments contraction and motility
Cholecystokinin (CCK)
Triggered by dietary lipids/peptides in the duodenum; causes coordinated gallbladder contraction + sphincter of Oddi relaxation
Emulsification Function
Bile salts and phospholipids act as biological detergents, breaking large fat globules into micro-droplets to maximize access for pancreatic lipase/colipase
Sphincter of Oddi (Choledochal Sphincter)
Thickening of smooth muscle surrounding the Ampulla of Vater. When closed (fasting), creates backpressure that diverts liver-derived bile through the cystic duct into the gallbladder
Fasting State / Closed Sphincter
Fasting: Bile diverted to Gallbladder
Duodenal Lipid Entry
CCK Release (I-cells)
1. Gallbladder Smooth Muscle Contraction
2. Sphincter of Oddi Relaxation