When a person thinks of digestion they usually think about what happens in the stomach. A lot has happened to digest the food way before it gets to the stomach. It starts in the mouth or oral cavity. It is a process called mechanical digestion. First, Mastication begins. Mastication is the chewing of the food. A person will crush, grind and tear the food apart. That gets the food ready for deglutition. Deglutition is the swallowing of the mashed up food. When we swallow peristalsis begins. Peristalsis is what happens to the food on the way to the stomach. Mostly peristalsis is the mixing and moving of food on the way through the esophagus, and into the stomach. It is also part of the movement through the intestines.
Chemical digestion also starts out in the mouth, but instead of using the tongue and teeth to break down the food chemicals are used. Enzymes and acid are in the saliva that is secreted in the mouth. Saliva begins to break down the food and carbohydrates into an absorbable solution. These nutrients will be absorbed by the body. What is not absorbed is moved on down through the body to the stomach. The stomach also secretes chemicals that are used in digestion. Pepsinogen breaks protein type foods down into protein molecules. Hydrochloric acid also breaks down food, kills microorganisms and converts pepsinogen to pepsin. Then the last chemical the stomach uses is gastrin. Gastrin is a hormone that helps to create more pepsinogen and hydrochloric acid. The food leaves the stomach and enters the small intestine.
In the intestines once again, Mechanical and chemical digestion are working together. Mechanical digestion is still breaking down the food, but now it focuses on fats. The fats that are broken down in the