What is the role of digestive enzymes?
What is the role of digestive enzymes?
Digestion:
1. Digestion means a person's ability to digest food.
2. In this process, food is treated with heat, enzymes, or a solvent to promote decomposition or to extract essential components from food.
Digestive enzymes:
1. Digestive enzymes are a group of enzymes that break down complex macromolecules into their smaller building blocks so that they can be easily absorbed by the body.
2. Digestive enzymes are secreted by the salivary glands and cells lining the stomach, pancreas, and small intestine.
Role of Enzymes in Digestion
Salivary Amylases
These enzymes are produced by the oral cavity. The main function of these enzymes is to split the carbohydrates by hydrolytic actions. The function of these enzymes are as follows:
Salivary amylases – 30% of starch molecules are converted into maltose by salivary amylases at a pH of 6.8.
Gastric Glands
Gastric glands are present in the mucosa of the stomach. The following types of cells are present in the gastric gland.
1. Mucous neck cells – These cells secrete mucus, which is used to protect the mucosal epithelium from concentrated HCl. This concentrated HCl is secreted by the oxyntic cells.
2. Peptic or chief cells – These cells secrete the proenzyme pepsinogen. It is in an inactive form. This inactive proenzyme pepsinogen is activated by HCl and converted into the active form of the enzyme, which is called pepsin. Pepsin is used to convert proteins into proteases and peptones.
3. Parietal or oxyntic cells – These cells secrete concentrated HCl and intrinsic factors. The intrinsic factor plays an important role in the absorption of vitamin B12. HCL is used to activate the proenzyme pepsinogen.
The following enzymes are secreted by gastric glands:
1. Pepsin – It is used to denature proteins into peptones and proteases.
2. Rennin – It is a type of proteolytic enzyme which is present in the infant’s gastric juice.
3. Lipase – Small amount of lipase enzyme is secreted by the gastric gland. It is used to convert fats to di and monoglycerides.
Small Intestine Enzymes
In the small intestine, three major digestive juices are secreted. These are as follows:
1. Bile juice
2. Pancreatic juice
3. Intestinal juice
Bile Juice
Bile juice is secreted by the liver. It is a yellowish color fluid. The main function of bile juice is to digest the lipid molecules and activate the lipase enzymes. Bile juice consists of the following components:
1. Bilirubin and biliverdin
2. Bile salts
3. Cholesterol
4. Phospholipids.
Bile juice helps in the emulsification of fats and also activates lipase enzymes.
Pancreatic Juice
The pancreatic juices are secreted by the pancreas.
Pancreatic juice consists of the following inactive enzymes.
These enzymes are activated by intestinal mucosal secretions.
1. Trypsinogen – An inactive form of trypsinogen is converted into an active form, trypsin by enterokinase (one of the intestinal mucosa secretions). Trypsin is used to convert the protein molecules into dipeptides.
2. Chymotrypsinogen – An inactive form of chymotrypsinogen is converted into an active form, chymotrypsin. Proteins are denatured into dipeptides by chymotrypsin.
3. Procarboxypeptidases – An Inactive form of procarboxypeptidase is converted into an active form, carboxypeptidase. Carboxypeptidase is also used to denature the protein.
4. Amylases – Amylases are used to denature the polysaccharides into the disaccharides.
5. Lipases – Lipases are used to convert fats into diglycerides and monoglycerides.
6. Nucleases – Nucleases are used to convert nucleic acids into nucleotides and nucleosides.
Intestinal Juice
The Intestinal mucous epithelium of the small intestine consists of the following:
1. Brush border cells.
2. Goblet cells.
The secretions of brush border cells and goblet cells from the intestinal juice in the small intestine. Intestinal juice consists of the following enzymes:
1. Disaccharidases – It is also called maltases. Maltases are used to convert maltose into glucose.
2. Dipeptidases – These enzymes are used to convert the dipeptides into simple amino acids.
3. Lipases – Lipases are used to convert diglycerides and monoglycerides into fatty acids and glycerols.
4. Nucleosidases – These enzymes are used to convert nucleotides into nucleosides, sugars, and bases.
5. Lactases – Lactases are used to convert lactose into simple glucose.
Digestion:
1. Digestion means a person's ability to digest food.
2. In this process, food is treated with heat, enzymes, or a solvent to promote decomposition or to extract essential components from food.
Digestive enzymes:
1. Digestive enzymes are a group of enzymes that break down complex macromolecules into their smaller building blocks so that they can be easily absorbed by the body.
2. Digestive enzymes are secreted by the salivary glands and cells lining the stomach, pancreas, and small intestine.
Role of Enzymes in Digestion
Salivary Amylases
These enzymes are produced by the oral cavity. The main function of these enzymes is to split the carbohydrates by hydrolytic actions. The function of these enzymes are as follows:
Salivary amylases – 30% of starch molecules are converted into maltose by salivary amylases at a pH of 6.8.
Gastric Glands
Gastric glands are present in the mucosa of the stomach. The following types of cells are present in the gastric gland.
1. Mucous neck cells – These cells secrete mucus, which is used to protect the mucosal epithelium from concentrated HCl. This concentrated HCl is secreted by the oxyntic cells.
2. Peptic or chief cells – These cells secrete the proenzyme pepsinogen. It is in an inactive form. This inactive proenzyme pepsinogen is activated by HCl and converted into the active form of the enzyme, which is called pepsin. Pepsin is used to convert proteins into proteases and peptones.
3. Parietal or oxyntic cells – These cells secrete concentrated HCl and intrinsic factors. The intrinsic factor plays an important role in the absorption of vitamin B12. HCL is used to activate the proenzyme pepsinogen.
The following enzymes are secreted by gastric glands:
1. Pepsin – It is used to denature proteins into peptones and proteases.
2. Rennin – It is a type of proteolytic enzyme which is present in the infant’s gastric juice.
3. Lipase – Small amount of lipase enzyme is secreted by the gastric gland. It is used to convert fats to di and monoglycerides.
Small Intestine Enzymes
In the small intestine, three major digestive juices are secreted. These are as follows:
1. Bile juice
2. Pancreatic juice
3. Intestinal juice
Bile Juice
Bile juice is secreted by the liver. It is a yellowish color fluid. The main function of bile juice is to digest the lipid molecules and activate the lipase enzymes. Bile juice consists of the following components:
1. Bilirubin and biliverdin
2. Bile salts
3. Cholesterol
4. Phospholipids.
Bile juice helps in the emulsification of fats and also activates lipase enzymes.
Pancreatic Juice
The pancreatic juices are secreted by the pancreas.
Pancreatic juice consists of the following inactive enzymes.
These enzymes are activated by intestinal mucosal secretions.
1. Trypsinogen – An inactive form of trypsinogen is converted into an active form, trypsin by enterokinase (one of the intestinal mucosa secretions). Trypsin is used to convert the protein molecules into dipeptides.
2. Chymotrypsinogen – An inactive form of chymotrypsinogen is converted into an active form, chymotrypsin. Proteins are denatured into dipeptides by chymotrypsin.
3. Procarboxypeptidases – An Inactive form of procarboxypeptidase is converted into an active form, carboxypeptidase. Carboxypeptidase is also used to denature the protein.
4. Amylases – Amylases are used to denature the polysaccharides into the disaccharides.
5. Lipases – Lipases are used to convert fats into diglycerides and monoglycerides.
6. Nucleases – Nucleases are used to convert nucleic acids into nucleotides and nucleosides.
Intestinal Juice
The Intestinal mucous epithelium of the small intestine consists of the following:
1. Brush border cells.
2. Goblet cells.
The secretions of brush border cells and goblet cells from the intestinal juice in the small intestine. Intestinal juice consists of the following enzymes:
1. Disaccharidases – It is also called maltases. Maltases are used to convert maltose into glucose.
2. Dipeptidases – These enzymes are used to convert the dipeptides into simple amino acids.
3. Lipases – Lipases are used to convert diglycerides and monoglycerides into fatty acids and glycerols.
4. Nucleosidases – These enzymes are used to convert nucleotides into nucleosides, sugars, and bases.
5. Lactases – Lactases are used to convert lactose into simple glucose.
