The digestive system processes the food and is also known as the alimentary canal or gastrointestinal tract (GI tract). Digestion of food starts with the mouth. The tongue and teeth mechanically break down food with the help of enzymes. The amylase, digestive enzyme, in the mouth breaks down mostly carbohydrates. When the food is swallowed it goes down the esophagus to the stomach.
In the stomach, hydrochloric acid continues to break down the food, especially any protein. As the food leaves the stomach, it’s called chyme. It’s then transported into the small intestines where most of the nutrient absorption occurs.
In the small intestines, bile from the gall bladder and lipase from the pancreas digest the fats. Amylase from the pancreas digests the rest of the carbohydrates. And, trypsin from the pancreas further digests proteins. The food goes from being some sort of solid substance before it enters the mouth to a smoothie consistency in the small intestines. The nutrients are absorbed and go to the liver for filtration and distribution.
The last part of the journey is through the large intestines, also known as the colon. The main function of the colon is to reabsorb water and electrolytes. Once the liquid has been removed it moves down into the rectum and is excreted through the anus.