Transcription: The digestive system breaks down incoming food into usable fuel or nutrients for the body. Food enters the digestive system through the mouth, where it is chewed and mixed with saliva, a watery mixture containing many enzymes. Saliva begins the chemical breakdown of food, while causing the chewed fragments to clump together into a moist ball, or bolus. After the bolus is swallowed, waves of muscular contraction called peristalsis transport the food through the esophagus and into the stomach. The stomach churns the food while cells in its lining secrete gastric juice, a combination of hydrochlo ...
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