Chemical reactions occur when atoms, molecules, and ions interact with one other to form new substances. Chemical bonds are broken and new bonds are formed. Chemical bonds between atoms follow rules based on patterns of electron distribution within the involved atoms. When reactions take place, energy exchange occurs. When chemical bonds are broken, energy is released. When new bonds are formed, energy is stored. There are many types of chemical reactions.

The blood and lymph systems are also vital to digestion's efficacy, transporting nutrients to the cells of the body where they are needed (Smith & Morton 2001). Again, most of the "action" of the accessory organs and their products takes place in the small intestine where the major work of both breaking down and absorbing nutrients takes place (SUNY 2010). It is here that the enzymes secreted by the

Chemical Digestion When the body can not break down food by the physical means it has, the body must therefore use chemical digestion to help finish the job. Chewing food with teeth is an example of physical digestion, but that is just the beginning of the process. Chemical digestion is also occurring at this starting point where digestive juices begin to counteract with the food to begin to break it down

Nutrition-Health-Science The Digestive System Mechanical digestion begins the process of digestion. Otherwise known as chewing, it "involves mixing, grinding, or crushing large pieces of food into small pieces" (Lab: Mechanical and chemical digestion, n.d, Chapter 38). In contrast, the process of chemical digestion occurs inside of the body within the digestive organs, "when digestive enzymes break down complex molecules, such as carbohydrates, into simple molecules, such as glucose" (Lab: Mechanical and chemical

Lipids and Proteins Lipids Lipids are fats and they are important to our health. When chemically digesting these lipids or fats, these molecules are broken down into smaller ones that can be more readily passed through the digestive system and into the bloodstream. This fat is transformed into triglycerides and can be used by the body for energy at a later time. Lipids like almost all food is first mechanically digested by the

Chemical Substances on Liver and Kidney Enzymes and Tissues A number of common consumer products and foods contain toxic substances that can have an adverse effect on liver and kidney enzymes and tissues (Steenland & Fletcher 2010). In addition, a number of naturally occurring and artificial substances contain toxic elements that are harmful to these organs (Steenland & Fletcher 2010). In this regard, Satarug and Nishjo (2004, p. 1512) report