Biology: Understanding the Digestive System

The facts about the digestive system are nothing short of surprising, if not astounding. For example about ten litres of fluid are secreted into the digestive tract every day, this includes saliva (from the mouth); stomach juices (such as hydrochloric acid); bile (from the gall bladder in the liver) and pancreatic juice (from the pancreas).
Also, the stomach produces juices which are very acidic (they are about pH2), and actually contain hydrochloric acid (remember that one from school science lessons?).
Not only that, but the length of the human digestive tract is about nine metres - so it is about five times longer than the average human height; imagine all of that tubing coiled up inside you!
In this age of obesity and poor quality food and drink bombarding us from all sides; I think it would be a good idea for Biologists and non-Biologists alike, to get an overview of what the digestive system is and how it functions. I really believe that knowing and understanding these kinds of things can better your well-being and health, through allowing you to make smarter choices when you eat; or when you feed your loved ones.
I would also like you to wonder at the facts I laid out at the start; and to consider that our digestive system usually manages to cope fairly well with whatever we throw at it; whether it is a curry and rice; a chocolate bar; a Thanksgiving supper; and few pints of beer; and so on. That is really something to marvel at: I will next present to you: the human digestive system!