Gallbladder Function and Motility
The gallbladder is a muscular reservoir that stores and concentrates hepatic bile between meals and contracts after eating to deliver a bolus of bile into the duodenum. Its filling and emptying are coordinated with the sphincter of Oddi by hormonal and neural signals, and disturbed motility — gallbladder stasis — is one of the conditions that favours stone formation.
Definition
Gallbladder motility is the cyclical filling, concentration, and emptying of the gallbladder that, in coordination with the sphincter of Oddi, regulates the storage of bile between meals and its delivery to the intestine after eating.
Scope
The topic covers the gallbladder's storage and concentrating function, the postprandial contraction driven largely by cholecystokinin, the reciprocal relaxation of the sphincter of Oddi, and the consequences of impaired emptying for bile stasis and gallstone risk. It is physiological reference material, not a clinical guide to gallbladder disease.
Core questions
- How does the gallbladder store and concentrate bile between meals?
- What signals trigger gallbladder contraction and emptying after a meal?
- How is gallbladder contraction coordinated with relaxation of the sphincter of Oddi?
- How does impaired gallbladder emptying (stasis) contribute to gallstone formation?
Key concepts
- Bile storage and concentration
- Cholecystokinin (CCK)-mediated contraction
- Sphincter of Oddi coordination
- Interdigestive (fasting) and postprandial emptying
- Gallbladder stasis and hypomotility
- Gallbladder ejection fraction
Mechanisms
During fasting the gallbladder relaxes and fills, absorbing water and electrolytes from hepatic bile to concentrate it many-fold. With a meal, fat and protein in the duodenum stimulate the release of cholecystokinin, which contracts the gallbladder smooth muscle and relaxes the sphincter of Oddi, expelling concentrated bile into the duodenum; vagal input and the migrating motor complex also modulate interdigestive emptying. When emptying is incomplete — for example in pregnancy, prolonged fasting, or metabolic states associated with reduced contractility — bile is retained and concentrated longer, promoting cholesterol supersaturation and nucleation that favour gallstone formation.
Clinical relevance
Gallbladder motility links normal digestive physiology to the pathogenesis of cholesterol gallstones and to functional biliary disorders. This entry describes the underlying physiology that such conditions disturb; it is educational and is not a basis for individual diagnostic or treatment decisions.
History
The gallbladder's storage and contractile role was established through twentieth-century physiology, and the identification of cholecystokinin as the hormone that empties the gallbladder linked intestinal signalling to biliary delivery. The recognition that impaired gallbladder emptying contributes to gallstone formation came from subsequent work on the lithogenic role of bile stasis.
Related topics
Seminal works
- portincasa-2006
- lammert-2016
Frequently asked questions
- What makes the gallbladder empty after a meal?
- Fat and protein entering the duodenum trigger the release of cholecystokinin, which contracts the gallbladder and relaxes the sphincter of Oddi so that concentrated bile flows into the intestine to aid fat digestion.
- Why does poor gallbladder emptying increase gallstone risk?
- When the gallbladder empties incompletely, bile is retained and concentrated for longer, which promotes cholesterol supersaturation and crystal nucleation — early steps in the formation of cholesterol gallstones.