Gallbladder and bile storage
the gallbladder is a saclike structure on the inferior surface of the liver that is about 8 cm long and 4 cm wide. Three tunics form the gallbladder wall: 1.an inner mucosa folded into rugae that allow the gallbladder to expand; 2. A muscularis externa, which is a layer of smooth muscle that allows the gallbladder to contract; and 3.an outer covering of serosa. The cystic duct connects the gallbladder to the common bile duct.
Bile is continually secreted by the liver and flows through the cystic duct to the gallbladder, where 40-70 ml of bile can be stored while the bile is in the gallbladder, water and electrolytes are absorbed, and bile salts and pigments become as much as 5-10 times more concentrated than they were when secreted by the liver. contraction of the gallbladder moves the stored bile into the duodenum.