Chew chew chew for it s the thing to do

The process of digestion begins in the mouth. The saliva in the moth, besides helping to masticate the food, carries an enzyme called ptyalin which begins the chemical action of digestion. It initiates the catabolism (breakdown) of carbohydrates by converting starches into simple sugars. This explains the need for thorough mastication of starchy food in the mouth. If this is not done the ptyalin cannot carry out its functions as it is active in an alkaline, neutral or slightly acid medium and is inactivated by the highly acid gastric juices in the stomach. Although enzymatic action starts while food is being chewed, digestion moves into high gear only when the chewed food has passed the esophagus and reached the stomach. While the physical action of peristalsis churns and kneads solid food into a semi-solid amorphous mixture called chyme, this mixture undergoes chemical changes initiated by gastric juices secreted by the walls of the stomach. These juices include mucus for lubricating the stomach, hydrochloric acid and gastric juice. The enzyme or active principle of the gastric juice is pepsin. This enzyme in combination with hydrochloric acid starts the breakdown of proteins into absorbable amino acids called polypeptides. An additional enzyme, rennin, plays an important role in the stomach of the infant. It curdles milk and allows the pepsin to work upon it. The gastric juice has no effect upon starches or fats.