Salivary amylase (a digestive enzyme) is secreted by the salivary glands (which produce saliva, which is a mixture of water, enzymes, and other chemicals) and begins the chemical breakdown of carbohydrates in bread, while lingual lipase (another digestive enzyme) begins the chemical breakdown of triglycerides... Stomach acid breaks down any food particles or liquids that make its way into your stomach. The acidic environment of the stomach also destroys most bacteria, so antibiotics can be used to kill off harmful bacteria such as E. coli and salmonella. Pancreatic juices contain both hydrochloric and phosphoric acids that are strong enough to break down most foods that enter the duodenum. The pancreas is located behind the stomach and above the small intestine. It is a large gland that produces insulin and other hormones. The small intestine is the longest part of the gastrointestinal tract, measuring from 1-3 feet long. It consists of three regions: the duodenum, jejunum, and ileum. The duodenum is the first portion of the small intestine and it is where digestion of starch and sugar occurs. Bacteria in the large intestine help break down remaining nutrients before they are absorbed into the bloodstream. The byproduct of this process is carbon dioxide, which leaves the body through our lungs. Food passes through the digestive system one piece at a time.