What is the function of the gallbladder in a healthy individual?

What Does the Gallbladder Do?

The gallbladder stores and concentrates bile during fasting, then contracts after meals to deliver bile into the duodenum for digestion, while simultaneously protecting the body from toxic bile acid accumulation. 1

Primary Functions

Storage and Concentration

• The gallbladder stores bile during the fasting state, with the sphincter of Oddi maintaining higher pressure in the common bile duct than in the duodenum or gallbladder, preventing bile from flowing into the intestine between meals. 1
• The organ concentrates bile while storing it, making it more potent for digestive purposes when needed. 1

Coordinated Bile Delivery

• The gallbladder empties mainly after meals (postprandially) through coordinated contraction of the gallbladder and simultaneous relaxation of the sphincter of Oddi, allowing controlled delivery of bile into the duodenum. 1
• This emptying occurs 5-20 minutes after food enters the stomach, well before the gastric contents reach the duodenum (which takes 1-3 hours), suggesting the gallbladder's role in digestion may be less significant than traditionally thought. 2

Hormonal Control Mechanism

• Cholecystokinin (CCK) is the principal hormone controlling gallbladder emptying after meals. 1
• CCK is produced in the proximal small bowel and released into the bloodstream after meal ingestion, binding to receptors in the gallbladder to cause contraction and to inhibitory neurons at the sphincter of Oddi to cause relaxation. 1
• Fibroblast growth factor-15, a hormone made by the distal small intestine in response to bile acids, is required for gallbladder filling between meals. 3

Protective Function

Bile Acid Management

• The primary protective function is reducing formation and concentration of toxic secondary bile acids (deoxycholic acid and lithocholic acid) by accumulating primary bile acids (cholic acid and chenodeoxycholic acid) in the gallbladder. 2
• This accumulation protects the liver, stomach mucosa, gallbladder itself, and colon from the toxic hydrophobic effects of secondary bile acids. 2
• The presence or absence of a gallbladder in mammals determines whether the body synthesizes more hydrophobic or hydrophilic bile acids. 2

Regulation of Enterohepatic Circulation

• More complete gallbladder emptying and faster intestinal transit increase the enterohepatic cycling of bile acids and lower the molar percent cholesterol of bile. 4
• The gallbladder's filling and emptying cycle regulates biliary lipid secretion rates and composition. 4

Clinical Implications

Normal Motility Patterns

• Both fasting and postprandial gallbladder motility are controlled by hormonal and neural mechanisms working in coordination. 1
• The gallbladder and small intestine serve as reservoirs for the bile acid pool during its enterohepatic circulation, regulating biliary secretion of bile acids. 4

When Function Fails

• Biliary pain occurs from increased gallbladder pressure caused by abnormal contraction patterns in the setting of structural or functional outflow obstruction. 1
• Approximately 80% of patients with gallstones remain asymptomatic throughout their lives, as the gallbladder can often function adequately despite stone presence. 5