Learning About the Digestive System

The Digestive System

The digestive system is the means by which the body transforms food into the energy it needs to build, repair, and fuel itself. On average, an adult body processes roughly 2 1/2  gallons of digested food, liquids, and digestive secretions each day.

Digestion begins in the mouth, where food is chewed by the teeth and mixed with saliva. The saliva helps lubricate both the mouth and the food and dissolves food particles to enhance taste and facilitate swallowing. Saliva also cleanses the mouth and teeth.

Chewing is important because as food is ground into increasingly fine particles, digestive juices containing enzymes mix with it. The more thoroughly food is chewed, the more complete the digestive functions are that occur at this point.

Once food is swallowed, it travels through the throat or pharynx to the esophagus. Both the pharynx and esophagus are muscular tubes that work through a series of contractions to move the food along and eventually empty into the stomach. The stomach then churns it into a paste called chyme, which is easier to digest. Some of the components of the food, such as water and sugar, are absorbed directly from the stomach into the bloodstream.

The next stop is the pyloric sphincter, which serves as the gateway to the small intestines. The digestion of starches, proteins, and fat occurs in the small intestine with the help of secretions that originate in the pancreas, liver, and intestinal villi.

How different nutrients are digested

Carbohydrates (starches and sugars), proteins, and fats are made up of extremely complex molecules that must be broken down or digested in order to be useful to the body. The process of digestion changes starches and complex sugars into simple sugars, proteins into amino acids, and fats and into fatty acids and glycerin. In these forms the nutrients can finally be absorbed into the bloodstream.

The digestion of carbohydrates begins in the mouth. Saliva contains the enzyme ptyalin, which changes some of the starches into sugar and makes them available to the bloodstream. The process continues in the stomach.

Proteins begin the digestive process only after reaching the stomach. This is due to the presence of hydrochloric acid and another enzyme called pepsin. Only a small amount of absorption occurs between the stomach and the bloodstream; most of it takes place after the contents have moved on to the small intestine, where it is met by pancreatic secretions that contain the enzymes amylase, trypsin, and lipase. Amylase works to change starch into simple sugars, trypsin breaks down partially digested proteins, and lipase splits fats into fatty acids and glycerin.

In addition to these fluids, the intestinal walls produce secretions that, while milder than pancreatic juices, perform similar functions. Bile, which is produced in the liver and stored in the gallbladder, also flows into the small intestine through the bile duct. Bile helps to further digest and absorb fats. In addition to producing bile the liver stores fats, carbohydrates, proteins, and vitamins. It also absorbs poisons and toxic substances before neutralizing them.

About 90% of absorption takes place in the small intestine. Food is digested when it has been broken down into particles small enough to be absorbed by the tiny blood lymph capillaries located in the walls of the small intestine. From there the nourishment is circulated to all the cells in the body.

Factors in digestive health

There are many ways to abuse and weaken the digestive system. Overeating, constant snacking and diluting digestive secretions with liquids can all place undue stress on digestive organs. Eating too fast, or feelings of emotional stress adversely affect digestion. In addition, as people age, the amount of hydrochloric acid (HCL) their bodies produce decreases. The decrease start between ages 35-45. By age 55, almost everyone has reduced levels of HCL.

Heredity may also be a factor in digestive health. Some people begin life with digestive organs predisposed to problems. Of course, when this is the case, any kind of abuse only compounds the problem.

What are enzymes

Enzymes are complex organic substances produced in plants and animals that catalyze or speed up chemical reactions in cells and organs. The digestive enzymes work with the body fluids to break down large chemical chains into smaller particles. The body is then able to absorb and utilize these smaller food particles.

The importance of enzymes

Enzymes are the catalysts of all chemical changes that occur in the body. They are found in both the food we eat and in our bodies. Without enzymes, body functions would be too slow to sustain life. Unfortunately, although they are absolutely essential, each person is born with a limited potential for enzymes. That's why maintaining an adequate supply of enzymes play such an important role in supporting the health of the body.

When the enzymes that exist naturally in foods are destroyed by heat, wilting or other abuse prior to digestion, the body must create new ones before it can properly digest the food. One of the best ways to help maintain a healthy supply of enzymes in the digestive system is to be fresh, raw fruits and vegetables as often as possible in addition to the enzymes these foods contain, fruits and vegetables are a rich source of the vital coenzymes (vitamins) needed by the body on a constant basis.