Numerous organs in the digestive system play a part in the production of digestive juices. These juices are released by several glands to aid with digestion. The salivary glands, stomach, liver, pancreas, and small intestine are the organs that release digestive juices. Here, let’s learn more about digestive juices.
Table of Contents
List of Digestive Juices
The list of five main categories of digestive juices and some of the enzymes secreted by them are mentioned below:
- Gastric juices
- Pepsin
- Renin
- Gastric lipase
- Gastric amylase
- Urease
- Gelatinase
- Intestinal juices
- Peptidase
- Lactase
- Maltase
- Sucrase
- Dextrinase
- Trehalase
- Intestinal lipase
- Pancreatic juices
- Pancreatic amylase
- Pancreatic lipase
- Trypsin
- Chymotrypsin
- Bile
- Saliva
Digestive Juices
Digestive fluids aid digestion by reducing food to simple nutrients. The body uses these nutrients for a variety of purposes after that.
Enzymes found in digestive juices accelerate bodily chemical processes. The main digestive enzymes used by the body to break down food are amylase, lipase, and protease, while many other specialised enzymes are also involved. Let us have a look at the digestive juices and enzymes involved in digestion.
Gastric Juice
The primary action of gastric juice is on proteins. Pepsin and rennin are the 2 main proteolytic enzymes present in gastric juice. Other enzymes found in gastric juice include gastric amylase, gelatinase, and lipase.
- Pepsin is usually secreted as inactive pepsinogen. Hydrochloric acid converts pepsinogen into pepsin. Then, proteins are changed into proteoses, peptones, and polypeptides by pepsin. Pepsin also makes milk curdle and digest (casein).
- Gastric lipase is a lipolytic enzyme that breaks down butter fat or tributyrin into fatty acids and glycerols.
- Gelatinase breaks down collagen and type IV and type V gelatin into peptides.
- Urease reacts with urea to create ammonia.
- Gastric amylase breaks down starch, but its impact is minimal.
- Rennin is present in infants and animals only and it curdles milk.
Intestinal Juice
Intestinal juices are released by pits between intestinal villi called crypts of Lieberkuhn. The following table will provide an overview of intestinal juices and their action.
|
Type |
Enzyme |
Substrate |
End Products |
|---|---|---|---|
|
Proteolytic Enzyme |
Peptidases |
Peptides |
Amino acids |
|
Amylolytic Enzyme |
Sucrase |
Sucrose |
Glucose and fructose |
|
Lactase |
Lactose |
Glucose and galactose |
|
|
Maltase |
Maltotriose and maltose |
Glucose |
|
|
Dextrinase |
Maltotriose, maltose and dextrin |
Glucose |
|
|
Trehalase |
Trehalose |
Glucose |
|
|
Lipolytic Enzyme |
Intestinal lipase |
Triglycerides |
Fatty acids |
Also Check:Role of Digestive Enzymes
Pancreatic Juice
A number of digestive enzymes like amylase, trypsin and lipase are contained in the liquid released by the pancreas known as pancreatic juice. The pancreatic juice’s neutralising activity is crucial because it shields the intestine from the damaging effects of chyme’s acidic nature.
- The amylolytic enzyme found in pancreatic juice is called pancreatic amylase. The pancreatic amylase turns starch into dextrin and maltose, just like salivary amylase does.
- Trypsin and chymotrypsin are the pancreatic juice’s two main proteolytic enzymes. Nuclease, elastase, collagenase, and carboxypeptidases are further proteolytic enzymes.
- Pancreatic lipase, cholesterol ester hydrolase, phospholipase A, phospholipase B, colipase, and bile salt activated lipase are among the lipolytic enzymes found in pancreatic juice.
Bile
Bile juice is secreted by liver cells and discharged into the bile canaliculus. In order for fat to be digested, it must first be emulsified by bile. Thus it acts as a detergent and helps in the absorption of fat. Bilirubin, a byproduct created during the breakdown of red blood cells, is also excreted through bile.
Saliva
Saliva is a digestive juice secreted by the salivary glands and is present in the mouth. It initiates chemical digestion while the mouth is still physically chewing the food. Saliva contains three digesting enzymes:
- Lingual lipase – It is a lipid-digesting (lipolytic) enzyme. Milk fats (pre-emulsified fats) are digested by it. Triglycerides are hydrolyzed into fatty acids and diacylglycerol by the action of lingual lipase.
- Salivary amylase – It is an enzyme that breaks down carbohydrates. It works by converting cooked or boiling starch into dextrin and maltose.
- Maltase – Maltose is transformed into glucose by the enzyme maltase, which has only trace amounts in human saliva.
Keep exploring BYJU’S Biology to learn more such exciting topics.
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See more:
- Digestive Enzymes
- Digestion and Absorption
- Diagram of Digestive System
- Large Intestine (Colon) – Diagram
