Chemical Digestion

Food you ingest will not do anything good for you in its natural form, no matter how nutritious it may be. Nutrients must be broken down to a small enough form to be absorbed into the bloodstream. Food is broken down into monomers by mechanical and chemical digestion. Mechanical digestion helps chemical digestion by physically breaking down food and moving it along the alimentary canal by chewing, swallowing, and peristalsis. On the other hand, chemical digestion breaks down food by the use of enzymes and acids. The breakdown of any type of food molecule by enzymes is referred to as hydrolysis. Chemicals digestion begins in the mouth when salivary glands produce extra saliva. Saliva contains salivary amylase, which begins the breakdown of carbohydrates, and salivary lipase, which begins the breakdown of fats. The mass of chewed food is called bolus. Once swallowed, the bolus travels down the esophagus, which has not absorbing function, and enters the stomach. In the stomach, gastric juice is produced, which mixes with the bolus and dissolves it into a thick, creamy liquid called chyme. Gastric juice contains pepsin, which breaks down proteins, and gastric lipase, which breaks down fats. The pH in the stomach is 1 to 2; it is very acidic. The stomach contains a thick mucus lining that prevents the stomach from being broken down and digested by its own acid. The esophageal sphincter prevents these stomach acids from leaking up and damaging the upper digestive tract. When the stomach acid does leak back into the esophagus, a person will experience heartburn. Chyme moves from the stomach through the pyloric sphincter and into the first part of the small intestines, the duodenum. In the entire digestive system, most all of absorption occurs in the small intestines. Here, the gallbladder secretes stored bile produced by the liver that helps in dissolving fats. The pancreas secretes pancreatic amylase (breaking down of carbs), pancreatic lipase (breaking...