Читать книгу Nutrition For Dummies - Carol Ann Rinzler - Страница 30

Your digestive system is a collection of organs specifically designed to turn complex substances (food) into basic components (nutrients). These organs form one long, exceedingly well-organized tube that starts at your mouth, continues down through your throat to your stomach, and then goes on to your small and large intestines to end at your anus.

In between, with the help of the liver, pancreas, and gallbladder, the usable (digestible) parts of everything that you eat are converted to simple compounds that your body can easily absorb to burn for energy or to build new tissue. The indigestible residue is bundled off and eliminated as waste.

Figure 2-1 shows the body parts and organs that comprise your digestive system.

© John Wiley & Sons, Inc.

FIGURE 2-1: Your digestive system in all its glory.

The digestive process run by these organs works in two simple ways, one mechanical and one chemical.

 Mechanical digestion takes place in your mouth and your stomach. First, your teeth break food into small, easy-to-swallow pieces that slide quickly from your mouth down through your esophagus (throat) to your stomach. Here, a churning action called peristalsis continues to break food into smaller particles and then moves the particles along to your small intestine, where the churning and breaking continues.

 Chemical digestion occurs at every point in the digestive tract where enzymes and other substances, such as hydrochloric acid (from stomach glands) and bile (from the liver), dissolve food, releasing the nutrients inside.

The rest of this chapter explains exactly what occurs and where along the digestive tract.