How the Body Uses Food

Food provides certain chemical substances needed for good health. The substances, called nutrients, perform one or more of three functions.

1) .They provide materials for building, repairing, or maintaining body tissues.
2). They help regulate body processes.
3). They serve as fuel to provide energy. The body needs energy to maintain all its functions.

The body breaks food down into its nutrients through the process of digestion. Digestion begins in the mouth. As food is being chewed, saliva moistens the particles. The saliva begins to break down such starchy foods as bread and cereals. After the food is swallowed, it passes through the esophagus, a tube that leads into the stomach. In the stomach, digestive juices speed up the breakdown of such foods as meat, eggs, and milk.

The partly digested food, called chyme (pronounced kym), passes from the stomach into the small intestine. In the small intestine, other juices complete the process of digestion. They break down the food into molecules that pass through the walls of the intestine and into the blood.

The blood distributes the nutrients to cells and tissues throughout the body. There the nutrients are broken down to produce energy or are used to rebuild tissues or to regulate chemical processes. Some of the nutrients are stored in the body, and others are used over and over again. But most of the nutrients undergo chemical changes as they are used in the cells and tissues. These chemical changes produce waste products, which go into the bloodstream.

Some of the wastes are carried to the kidneys, which filter them from the blood. The body expels these wastes in the urine. The liver also filters out some wastes and concentrates them into a liquid called bile. Bile is stored in the gall bladder until it is needed to aid in digestion. Then the gall bladder empties bile into the small intestine. From there, any remaining bile passes into the large intestine, along with parts of the food not digested in the small intestine. The large intestine absorbs water and small amounts of minerals from this waste material. This material, along with bacteria present in the large intestine, becomes the final waste product, the feces, and it is eliminated from the body.