What Are Digestive Juices?

Digestive juices in the human body are secretions that contain enzymes that break down food into nutrients. These juices are produced by several glands in the digestive system which help in the digestion process. The digestive juices are produced by the salivary glands, stomach, liver, pancreas, and small intestine. The body absorbs nutrients and uses them. In simple words, digestive juices generally create the conditions that are needed for the digestion process. In this article, we are going to discuss the different digestive juices and their functions in detail.

What are Digestive Juices?

Digestive Juices Definition: Digestive juices are those secretions by different glands of the digestive system that help to break down the food into small particles so the body can absorb them.

Digestive juices help to break down the food in our bodies. They are secreted from the different glands of our digestive system to help in the digestion process including the salivary glands, stomach, liver, pancreas, and small intestine. The enzymes present in these juices accelerate the chemical processes of digestion. The major digestive juices are amylase for carbohydrates, lipase for fats, and protease for proteins, with other enzymes also playing important roles in the process.

Digestive Juices List

There are five major categories of digestive juices as mentioned below.

• Saliva: Saliva is produced by the salivary glands that are present in the mouth.
• Gastric juice: They are produced by the glands present in the stomach lining.
• Bile: Bile is generally produced by the liver and stored in the gallbladder, released into the small intestine.
• Pancreatic juice: It is produced by the pancreas, and released into the small intestine.
• Intestinal juice: These are produced by glands in the wall of the small intestine.

Let us learn about the enzymes that are present in the main digestive juices.

Digestive Juices	Present Enzymes
Saliva	Amylase Lipase
Bile	*
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

Digestive Juices in Mouth -Saliva

Salivary glands are parotid, submandibular, and sublingual. They are small buccal glands. Here are some major characteristics and works of Saliva as mentioned below.

• The secretion of saliva generally ranges between 800-1500 milliliters daily.
• Saliva contains two major enzymes including ptyalin and mucin.
• Ptyalin is an a-amylase that helps in the process of digestion.
• Mucin is a lubricating agent that is also used for surface protection.
• Saliva dissolves the foodstuff and helps to taste the food.
• It breaks down the starch into maltose with the ptyalin enzyme.
• Lingual lipase is a fat-digesting enzyme. It helps break down fats from milk into fatty acids and diacylglycerol.
• Salivary amylase is an enzyme that breaks down carbohydrates. It changes starch into dextrin and maltose.
• Maltase is another enzyme that transforms maltose into glucose, but it is found only in a small amount in human saliva.

Here is the composition of Saliva as mentioned below.

Water	99.5%
Solid	0.5%
Organic	Pyyalin, Lysosome, Mucin, Urea, Cholesterol, Amino Acids
Inorganic	Various ion
Antimicrobial Agents	Secretory IgA and lysozymes
Gases	N2 and O2

Digestive Juices in Stomach -Gastric Juice

Gastric juice mainly works on proteins. It contains two main enzymes for breaking down proteins: pepsin and rennin. Other enzymes in gastric juice include gastric amylase, gelatinase, and lipase. Here are some major characteristics and work of Gastric Juice as mentioned below.

• Pepsin is secreted as the inactive pepsinogen. It gets activated by hydrochloric acid.
• Once activated, pepsin breaks down proteins into smaller pieces like proteoses, peptones, and polypeptides.
• Pepsin also helps curdle milk and digest casein.
• Gastric lipase breaks down butter fat or tributyrin into fatty acids and glycerols.
• Gelatinase breaks down collagen and certain types of gelatin into peptides.
• Urease reacts with urea to produce ammonia.
• Gastric amylase helps break down starch, but its effect is minimal.
• Rennin, found in infants and animals, curdles milk.

The composition of Gastric Juice is mentioned below.

Water	99.5%
Solids	0.5%
Hydrochloric acid	It converts pepsinogen to pepsin for chemical digestion.
Pepsinogen	It digests the proteins.
Mucus	It forms a protective barrier which is known as Mucus-bicarbonate barrier.
Intrinsic Factors	They combines with the vitamin B12 and make it absorbable.
Gastrin	It stimulates the secretion of Gastric Acids.
Histamine	It stimulates the secretion of Gastric Acids.

Read More: Stomach – Anatomy, Diagram & Functions

Digestive Juices in Liver -Bile

Bile juice secreted from the liver cells and goes into the bile canaliculus. It helps to digest fat by breaking it into smaller pieces. This helps the body absorb fat. Bile helps remove bilirubin, a byproduct of the breakdown of red blood cells. Here are some functions of bile as mentioned below.

• Helps break down fat into smaller pieces so the body can digest it easily.
• Helps absorb fat and vitamins that dissolve in fat.
• Removes bilirubin and extra cholesterol from the body.
• Releases a fluid in the small intestine to balance the acidity from the stomach.

The composition of bile is mentioned below.

Bile acids	Bile acids helps to break down the large fats onto small particles. It helps to absorb the fat in the small intestine.
Phospholipids	They are the basic structure of cell membranes. It helps in the process of digestion and absorption of fats.
Proteins	Proteins of Bile serves as the catalysts in biochemical reactions.
Cholesterol	Cholesterol is converted into bile acids in the liver. Then they released into the bile and helps in the fat digestion and absorption.
Bilirubin	Bilirubin is found in bile. It is a fluid that helps us to digest food.

Read More: Role of Bile Salt in Digestion

Digestive Juices in Pancrease -Pancreatic Juice

Pancreatic Juice is a liquid that is secreted from the pancreas. It contains so many important enzymes like amylase, trypsin, and lipase that help digest food in the intestine. One key function of the pancreatic juice is to neutralize the acidity of the food that is coming from the stomach. This is crucial because it protects the intestine from being harmed by the acidic nature of the chyme. Here are some major functions of the Pancreatic Juice as mentioned below.

• Pancreatic amylase breaks down the starch into dextrin and maltose. They works as similar as the salivary amylase.
• Trypsin and chymotrypsin are the main proteolytic enzymes that break down proteins into smaller peptides.
• Other proteolytic enzymes like nuclease, elastase, collagenase, and carboxypeptidases perform the further protein digestion processes.
• Pancreatic lipase, cholesterol ester hydrolase, phospholipase A, phospholipase B, colipase, and bile salt activated lipase are responsible for breaking down fats in the digestive system.

Read More: Pancreatic Juice – An Overview

Digestive Juices in Small Intestine – Intestinal Juice

Intestinal juices is secreted from the pits that is known as crypts of Lieberkuhn. It is located between intestinal villi and plays a crucial role in the digestive processes. The following table outlines the various types of intestinal juices along with their respective functions.

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

Now, let us discuss the three types of Enzymes present in the Intestinal Juice.

Proteolytic Enzyme

Proteolytic enzymes also known as proteases. They are the enzymes that catalyze the process of breakdown of the proteins into smaller peptides or amino acids by hydrolyzing peptide bonds. Proteolytic enzymes play a key role in protein digestion.

Amylolytic Enzyme

Amylolytic enzymes also known as amylases. They are the enzymes that catalyze the hydrolysis of starch and glycogen into smaller carbohydrate molecules such as maltose, maltotriose, and dextrins.

Lipolytic Enzyme

Lipolytic enzymes are enzymes that catalyze the hydrolysis of triglycerides or fats into glycerol and fatty acids. Lipolytic enzymes play a major role in lipid digestion.

Read More: Difference Between Carbohydrates and Lipids

Conclusion – What Are Digestive Juices?

Digestive juices help to break down the food in our bodies. They are secreted from the different glands of our digestive system to help in the digestion process including the salivary glands, stomach, liver, pancreas, and small intestine. Saliva dissolves the foodstuff and helps to taste the food. It breaks down the starch into maltose with the ptyalin enzyme. Gastric juice mainly works on proteins. It contains two main enzymes for breaking down proteins: pepsin and rennin. Bile juice secreted from the liver cells goes into the bile canaliculus. Pancreatic Juice is a liquid secreted from the pancreas. It contains so many important enzymes like amylase, trypsin, and lipase that help digest food in the intestine. Intestinal juices secreted from the pits that is known as crypts of Lieberkuhn. It plays a crucial role in the digestive processes.

FAQs – What are Digestive Juices?

What are the Digestive Juices?

Any of the secretions entering the digestive tract that contain digestive enzymes. They include saliva, gastric juice, intestinal juice, and pancreatic juice.

What is Called Intestinal Juice?

Intestinal juice or succus entericus is the alkaline yellowish watery fluid released by the glands lining the inner wall of the small intestine. The alkaline nature of the fluid helps it to counter the acidic chyme coming from the stomach.

What are the Three Intestinal Juices?

The bile, pancreatic juice and the intestinal juice are the secretions released into the small intestine.

What are the 4 Gastric Juices?

The stomach secretes water, electrolytes, hydrochloric acid, and glycoproteins, including mucin, intrinsic factor, and enzymes.

How Many Digestive Juices?

Lipase (for fat digestion), amylase (for carbohydrate digestion), and protease are often secreted (for protein digestion). Enzymes, not acidic conditions, cause pancreatic proteases (enterokinase converts trypsinogen to trypsin).

Which Enzyme is Present in Saliva?

Ptyalin is the starch hydrolyzing enzyme secreted by salivary glands in human beings. It is also called as salivary amylase. Ptyalin secreted in the mouth brings about digestion of starch in the mouth itself.

Why do we Call Saliva Digestive Juice?

Saliva contains special enzymes that help digest the starches in your food. An enzyme called amylase breaks down starches (complex carbohydrates) into sugars, which your body can more easily absorb.

What is Intestinal Juice or Succus Entericus?

The intestinal juice is also called succus entericus. This juice contains a variety of enzymes like disaccharidases (e.g., maltase, sucrase, lactase), dipeptidases, lipases, nucleosidases, etc.

What are the Different Types of Digestive Juices?

The different types of digestive juices include stomach acid, bile produced by the liver, and enzymes such as amylase, lipase, and protease secreted by different organs like the pancreas and small intestine. They help in digestion.