Digestion is a complex process of breaking down foods into components that can be easily absorbed by the body. Digestion begins in the mouth, pit stops in the stomach and finishes with a journey through the intestines. Along the way, a variety of enzymes are secreted; these function specifically in the digestion of fats, proteins and carbohydrates.
Salivary and Pancreatic Amylase
Amylase is an important enzyme that breaks down starch or carbohydrates in food. Salivary amylase is produced in the mouth by the salivary glands and is the first enzyme involved in chemical digestion. Pancreatic amylase is secreted by the pancreas into the duodenum, or first section of the small intestines. Together, these enzymes break down the polysaccharide starch into di, tri and oliosaccharides, which are then broken down by other digestive enzymes into monosaccharides, such as glucose, which is absorbed and used as energy for the body, according to the University of California Berkley.
Pepsin
Pepsin is secreted by the gastric glands and is responsible for breaking down proteins into smaller pieces, called polypeptides. Pepsin is secreted in its inactive form, known as pepsinogen, and is converted into its active form in the acidic environment of the stomach. The acidic environment of the stomach also alters the shape of proteins, allowing pepsin access to break the peptide bonds holding them together. Pepsin's role in breaking protein down into polypeptides allows enzymes in the small intestines to further break down these polypeptides into amino acids for use by the body, according to the University of Cincinnati Clermont College.
Proteases
Protein digestion is initiated by pepsin in the stomach but is finished by proteases in the small intestines. Proteases are secreted by the pancreas and function to break down polypeptides, or broken down proteins, into amino acids -- the building blocks critical to life. Trypsin and chymotrypsin are the two primary proteases secreted by the pancreas, according to Colorado State University.
Bile
Bile is a digestive fluid primarily involved in the digestion of fats. Secreted by the liver and stored in the gallbladder, bile is a complex mixture of bile acids, potassium and sodium, cholesterol and bilirubin -- a byproduct from the breakdown of red blood cells, according to MedlinePlus. In the small intestine, the bile acids break down dietary fat and fat-soluble vitamins into fatty acid components, which can then be absorbed by the body. Bile acids are synthesized from cholesterol and thus play a large role in the breakdown and elimination of cholesterol from the body, according to Colorado State University.
References
- Colorado State University: Exocrine Secretions of the Pancreas
- Colorado State University: Secretion of Bile and the Role of Bile Acids In Digestion
- SydPath: Amylase
- University of California Berkley: The Digestive System
- University of Cincinnati Clermont College: Effects of Antacids on Pepsin
- Clinton Community College: Digestive System
