Your Digestive System

Someone asked me the other night which part of the intestines does food get digested first.  I said the small intestine.  The sequence is like this:  

First, the mouth: chewing and mixed by saliva.  After the mouth, food passes through the esophagus for a bit more digestion.  That's second. Third, the food reaches the stomach where it is chemically and muscularly destroyed by the stomach muscles and powerful hydrochloric acid.  From the stomach, you food transports to the small intestine, where the majority of your foods nutrients are absorbed.  The large intestines absorb water and render your food more suitable for waste.  There is some digestion in the large intestine as well.  Check out the photo:

This a pretty good description of your digestive system:

The primary functions of the small intestine are to break down food by means of chemicals and to absorb some of the food's nutrition through the intestine walls. Food enters the small intestine from the stomach and travels through the intestine by means of peristalsis. The first section of the small intestine, called the duodenum, receives digestive juices from the pancreas that aid in the breakdown of fats, proteins and carbohydrates. These digestive juices also help to neutralize acid that accompanies the food from the stomach. Bile from the gall bladder enters the duodenum to further aid in the breakdown of fatty substances. 

The walls of the small intestine contain small protruding components called microvilli, and these small structures help to increase the wall's absorption capabilities so that large amounts of nutrients may pass through the intestine walls into the blood stream. The remaining waste passes into the large intestine for later expulsion.  

Next is how to take care of it, the whole thing, as well as the different parts?  How does one avoid a leaky gut? Where does it usually occur?  

This you already knew:

The most acidic part of the human gastrointestinal tract is the stomach, which is generally around pH 1 to pH 3. The high acidity in the stomach fights bacteria that are ingested with food. As the distance increases from the stomach, the pH level gradually increases. The large intestine is pH 5.5 to pH 7.