When you eat, your body breaks food down to a form it can use to build and nourish cells and provide energy. This process is called digestion.
Your digestive system is a series of hollow organs joined in a long, twisting tube. It runs from your mouth to your anus and includes your esophagus, stomach, and small and large intestines. Your liver, gallbladder and pancreas are also involved. They produce juices to help digestion.
There are many types of digestive disorders. The symptoms vary widely depending on the problem. In general, you should see your doctor if you have
Blood in your stool
Changes in bowel habits
Severe abdominal pain
Unintentional weight loss
Heartburn not relieved by antacids
NIH: National Institute of Diabetes and Digestive and Kidney Diseases