This lecture series on gastrointestinal diseases covers the pathology of the GI tract from the esophagus to the pancreas. It discusses six major pathological issues including muscle and nerve problems, obstructions, enzyme deficiencies, surface area reduction, blood supply abnormalities, inflammation/infection, and tumors. The lecture also reviews the functions and common diseases of each GI tract segment including the esophagus, stomach, small intestine, large intestine, and accessory organs.