Trivia: What digestive system organ is NOT part of the GI tract?
Correct Answer: Gallbladder
So why is this answer correct? : The digestive system includes two subsystems: the GI (gastrointestinal tract) and the biliary system. The GI tract is a series of connected, hollow organs that help digest food and absorb nutrition. These organs include the mouth, esophagus, stomach, small and large intestines, and anus.