Normally, the downstream gallbladder stores and concentrates the bile which originates in liver hepatocyte cells and is released into the microscopic component of the biliary system by the liver. Through aggregating tubules of increasing diameter, the bile leaves the liver and reaches the upstream (proximal) component of the common bile duct. Apparently, the common bile duct beyond (distal to) the gallbladder tends to normally have a greater tone so that the bile backs up into the gallbladder.