Digestive Enzymes and their functions

What are digestive enzymes?

Enzymes which break down macromolecules into smaller units are called digestive enzymes. The larger molecules are broken down into smaller particles so that they can be easily absorbed by the body.

These enzymes are found in the digestive system of the body of animals and human beings. For carnivorous plants, they are found in the traps. Digestive enzymes help in the digestion of food. Apart from the digestive tract, digestive enzymes are heavily found in the saliva which is a secretion of the salivary glands and it plays a major part in the process of digestion.

They are also found in the stomach where the enzymes are secreted by the cells in the stomach lining. Pancreatic juice and intestinal secretions also contain digestive enzymes.

Why are digestive enzymes important?

Our body is built in such a way that we eat food and the nutrients from the food are absorbed by the body which nourishes and strengthens us. But, our body is not capable of absorbing the nutrients directly from the food.

These come in the role of digestive enzymes. The enzymes break down the food into smaller units which the body can absorb, thus facilitating digestion. Thus, digestive enzymes are very important for the well-being of the body.

Digestive enzymes can be classified on the basis of their target substrates. The main digestive enzymes along with their substrates are as follows:

  1. Protease and peptidases- They split proteins into amino acids and small peptides
  2. Amylase- Carbohydrates like starch and sugar are split by Amylase into glucose
  3. Lipase- Lipase splits fat into three kinds of fatty acids and glycerol molecule
  4. Nuclease- Nucleotides and nucleic acids are split by nucleases

List of digestive enzymes and their area of function


We eat our food through the mouth. The complex food particles need to be broken down into simpler molecules which are soluble and are easily absorbed. Therefore, digestive enzymes which are secreted by the salivary glands and the oral cavity break down the food into simpler units in the mouth.

  • Lipid digestion starts in the mouth, which is done by the enzyme lingual lipase. It helps in digesting the lipid or fat molecules.

  • Salivary amylase is an enzyme which helps in the breakdown and digestion of carbohydrates. They are broken down into simple forms of sugar or glucose, which can be directly absorbed into the bloodstream.

  • The salivary glands contain serous glands and mixed glands as well. Serous glands secrete water, which is rich in electrolytes and enzymes. Mixed glands contain many kinds of cells like serous cells, mucous cells, and its secretion is high in mucous content.

  • Haptocorrin, also called the R-factor, aids in digesting Vitamin B12. The molecules of vitamin B12 bound with Haptocorrin, where they are protected from the acids, which are released in the stomach to maintain the pH level.

  • Lysozyme is an enzyme which has an antiseptic function in the process of digestion.


The stomach secretes enzymes known as gastric enzymes. They help in breaking down the food into smaller particles which can be easily digested and absorbed by the bloodstream.

  • Pepsin is one the most important gastric enzymes which break down protein into smaller particles. Proteins are the building blocks of our body. Protein is broken down into peptides and amino acids. In this way, protein digestion begins in the stomach.

  • Hydrochloric acid is produced by the stomach cells. The role of HCL acid is to denature the ingested proteins and kill any bacteria or virus which is in the food. HCL also plays a part in activating pepsin and pepsinogen.

  • Mucin is an enzyme which is used in destroying the harmful microbes like bacteria and virus.

  • Gastrin is an important hormone. It is produced by the G cells and it is an endocrine hormone. Since it is an endocrine hormone, it can easily enter the bloodstream and then it comes back to the stomach to stimulate the parietal cells.

  • Gastric lipase is a secretion which, the gastric chief cells secrete. The gastric chief cells also produce pepsinogen.


The pancreas is a gland which is both endocrine and exocrine. It produces hormones which are released directly into the circulatory system. It has many functions like controlling the glucose metabolism and secretion of digestive enzymes.

  • Ductal cells release secretions which are rich in bicarbonate that is stimulated by secretin hormone. These secretions maintain the acidic level of the stomach.

  • Pancreatic juice consists of several digestive enzymes like trypsinogen, chymotrypsinogen, carboxypeptidase, elastases and pancreatic amylases.

Apart from these, the small intestine also secretes digestive enzymes. Digestive enzymes are very important as they help in breaking down the food into smaller particles so that the nutrients can be easily extracted from them. Thus, digestive enzymes play a key role in maintaining and regulating the normal functions of the body.

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