Working with Digestive Enzymes
Digestive Enzymes: The Three Types
Digestive enzymes are located within the gastrointestinal tract (digestive system) of the body. These enzymes function to break down specific substances including carbohydrates, fats, and proteins. The break down of these complex molecules into simpler molecules is necessary for the process of absorption. There are three main types of enzymes within the digestive system, all defined by location (gastric, pancreatic, and intestinal enzymes). The liver also has important contributions to the overall digestion process.
Gastric enzymes are located in the stomach, but are typically secreted there through the accessory organs and are responsible for the breakdown of specific substances.
- Pepsin: A peptidase released by chief cells responsible for breaking proteins into smaller fragments known as peptides.
- Gastric amylase: Responsible for the breakdown of starch products.
- Gastric lipase: Responsible for the digestion of fats into monoglycerides and fatty acids.
- Gelatinase: Breaks down proteoglycans into amino acids, polypeptides, and peptides, typically from meat products, including gelatin and collagen.
Pancreatic enzymes are produced by the pancreas and secreted to other organs for digestion, including the stomach and small intestine. The pancreas is responsible for the production and delivery of several enzymes. The process of digestion is impossible without the production of these enzymes.
- Pancreatic amylase: There are several types of amylases, including alpha, beta, and gamma. All degrades carbohydrates and starches, except cellulose and glycogen.
- Elastase: Mainly responsible for the breakdown of proteins known as elastins. Elastins are part of connective tissue, in conjunction with collagen.
- Nuclease: Responsible for the degradation nucleic acids into nucleotides through bond cleavage.
- Trypsin: Small intestine peptidase breaks down proteins into amino acids.
- Chymotrypsin: Small intestine peptidase also breaks down proteins.
- Carboxypeptidase: A protease responsible for the break down of peptide fragments into individual amino acids.
- Steapsin: Responsible for the degradation of triglycerides. Broken triglycerides include glycerol and other fatty acids.
Enzymes of the Small Intestine
- Maltase: Responsible for the breakdown of the specific disaccaride maltose into glucose.
- Isomaltase: Isomaltase is responsible for the breakdown of maltose into isomaltose.
- Sucrase: Sucrose must be broken into either fructose or glucose, sucrase is responsible for this.
- Lipase: Responsible for fatty acid breakdown.
- Lactase: Lactose must be broken down into glucose and galactose. This process is accomplished through the use of lactase.
Contributions of the Liver
The liver is responsible for the secretion of a substance known as bile. Bile is secreted by hepatocytes (liver cells) and is stored by the gall bladder. Bile aids to degrade fats in the duodenum. The duodenum is the beginning portion of the small intestine. Bile increases absorption rates by the small intestine. Particularly, bile is responsible for increasing the surface area of fats. A larger surface area speeds the degradation process. When chyme, the name termed for food digested by the stomach, reaches the duodenum, bile is secreted to aid in the completion of the digestion process.