The process of converting food into chemical substances that can be absorbed into the bloodstream and used by body tissues and organs is called digestion. Digestion is a complex process that involves the breakdown of food into smaller molecules that can be absorbed and used by the body for energy and nutrition. Digestion begins in the mouth, where food is mechanically broken down by chewing and mixed with enzymes that begin to break down the food chemically. The partially digested food then passes through the esophagus and into the stomach, where it is further mechanically and chemically broken down. From the stomach, the partially digested food moves into the small intestine, where it is mixed with bile and enzymes that help to complete the digestion process. The resulting small molecules, such as amino acids and simple sugars, are then absorbed into the bloodstream and transported to the body's tissues and organs to be used for energy, growth, and repair.