The mouth plays a critical role in mechanical digestion as chewing breaks apart food, which lessens the burden on the rest of the digestive system. But the mouth also secretes amylase, an enzyme that breaks down starches -- long chains of sugar molecules also known as polysaccharides -- into smaller molecules containing only two sugar molecules, known as maltose. This is the first step in the production of glucose -- the simple sugar that cells require for energy.
Mouth
The mouth plays a critical role in mechanical digestion as chewing breaks apart food, which lessens the burden on the rest of the digestive system. But the mouth also secretes salivary amylase, an enzyme that breaks down starches -- long chains of sugar molecules also known as polysaccharides -- into smaller molecules containing only two sugar molecules, known as maltose. This is the first step in the production of glucose -- the simple sugar that cells require for energy.
Stomach
As you swallow, the food travels through the stretchy tube known as the esophagus into the stomach. The cells lining the stomach produce stomach acid, known as hydrochloric acid, and pepsinogen -- a precursor to the enzyme known as pepsin. Pepsin breaks the bonds between the amino acids of proteins. The body then absorbs the individual amino acids and uses them to build the thousands of proteins needed throughout the body. Cells in the stomach also produce gastric amylase to breaks down starch into maltose.
Pancreas
Although the pancreas is not part of the digestive tract --- food particles do not travel through it --- it produces enzymes essential to digestion. Pancreatic juice empties into the small intestine. The stomach slowly releases the partially digested food into the small intestine where the pancreatic enzymes can go to work. One enzyme, known as lipase, breaks down fat molecules into smaller fatty acids the body will use to build cell membranes and produce hormones. Pancreatic amylase works similar to salivary amylase, breaking starch down into maltose. Trypsin and chymotrypsin break the bonds between specific amino acids in proteins.
Small Intestines
The small intestine absorbs the majority of the nutrients and energy from food. It also produces enzymes to break down the food molecules even further. Peptidase enzymes, including carboxypepidase and aminopeptidase, continue to breakdown protein molecules. Maltase breaks down the maltose formed in the mouth and stomach into individual glucose molecules the body can use for energy.
