Stages of Digestion Four Stages of Digestion • • • • Ingesting Digesting Absorbing Eliminating Stage 1:Ingesting • The starting point of the digestion process. Stage 2: Digesting • Mouth: Mechanical and Chemical digestion begins. • Mechanical digestion is the chewing and breaking food down into smaller pieces • Each small piece of food is a bolus • Saliva lubricates the food, and contains an enzyme, called amylase. • Chemical digestion occurs when amylase begins to break down complex carbohydrates. • Esophagus: as food passes through the pharynx, the epiglottis covers the airway tube. • The food moves on to the esophagus. • The esophagus is a tube that connects the pharynx and the stomach. • The esophagus is long and muscular • The bolus is pushed through the esophagus in a process called peristalsis. Stomach • Your stomach is like a stretchable muscular bag. • Inside the stomach is gastric juice, which is very acidic. • The stomach walls are lined with mucus, that protects the tissue. • Pepsin is an enzyme which breaks down protein, and needs an acidic environment. • The bolus breaks down into a liquid called chyme. Small Intestine • Once the chyme leaves the stomach, it empties into the small intestine. • The first metre is called the duodenum. Digestion is complete after foods leaves. • Within the first 30 cm are ducts that connect to other organs. • Pancreas: produces enzymes • Liver: produces bile.