This video by TED-Ed gives a thorough overview of the digestive system, laying out the full process of digestion along with all of the organs and chemicals in the body involved in the process. The animations, clear narration, and fun facts about one of the most complicated systems in the body make this video especially enjoyable to watch to gain a general but also highly detailed introduction to the digestive system. 

How Your Digestive System Works - TED-Ed