Mechanisms by which bile secretion from the gallbladder is controlled

Question 1

During the interdigestive period (between meals), is the sphincter of Oddi contracted or relaxed?

Answer 1

Contracted - to prevent bile from entering the duodenum

Question 2

How does bile enter the gallbladder?

Answer 2

Pressure in the common bile duct increases, causing bile to flow into the gallbladder

Question 3

How does the gallbladder concentrate bile?

Answer 3

Epithelial cells lining the gallbladder reabsorb water and electrolytes

Question 4

Describe how bile secretion is regulated

Answer 4

Fatty acids and amino acids in the duodenum stimulate endocrine cells to release CCK (after a meal)
CCK then stimulates the contraction of smooth muscle in the gallbladder, as well as the relaxation of the sphincter of Oddi —-> bile release

Gastric acid in the duodenum leads to the stimulation of other endocrine cells to release secretin
Secretin inhibits gastric acid secretion/motility, while promoting pancreatic ductal cell release and bile duct release of bicarbonate and water