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The Role of Gastric Juice in Digestion: A Comprehensive Guide

The Role of Gastric Juice in the Digestion: A Comprehensive Guide
Important Digestive Juices

Digestion and absorption are two crucial processes that occur in the body. Digestion is the mechanical and enzymatic breakdown of food into molecules that can be absorbed into the bloodstream. The diet comprises three macro-nutrients that must be digested before absorption; lipids, carbs, and proteins. Numerous organs in the digestive system contribute to the synthesis of digestive fluids. A variety of glands produce these liquids to facilitate digestion. The salivary glands, stomach, liver, pancreas, and small intestine are the organs that secrete digestive juice. The digestive fluids contain enzymes, which help break down food into its numerous components. For example, the salivary glands in the mouth secrete saliva one of the digestive juice that helps convert the starch in food into simpler sugar.

Digestive Juices in detail

Digestive fluids promote digestion by breaking down food into simple nutrients. Following that, the body puts these nutrients to use in a variety of ways. Enzymes contained in gastric fluids speed up biological chemical processes. The primary digestive enzymes utilized by the body to break down food are amylase, lipase, and protease, but many other specialist enzymes are also involved. Let's have a look at the digestive fluids and enzymes involved in digesting.

The five major groups of digestive juices, as well as some of the enzymes released by them, are listed below:

1. Gastric Juice

The main action of gastric juice is on proteins. Pepsin and rennin are the two main proteolytic enzymes found in gastric juice. Other enzymes detected in gastric juice are gastric amylase, gelatinase, and lipase.

  • Pepsin is usually secreted as inactive pepsinogen. Hydrochloric acid converts pepsinogen into pepsin. Further, by pepsin proteins are changed into proteoses, peptones, and polypeptides. Likewise pepsin also helps to digest casein, the protein found in milk.

  • 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.

2. Intestinal Juice

Pits between intestinal villi, known as Lieberkuhn crypts, discharge digestive juices. Some of the enzymes it contains are;

  • Peptidase

  • Lactase

  • Maltase

  • Sucrase

  • Dextrinase

  • Trehalase

  • Intestinal lipase

3. Pancreatic Juice

The pancreas is indeed the enzyme "powerhouse" of digestion. It produces the most critical digestive enzymes, which degrade carbs, proteins, and lipids.

The liquid secreted by the pancreas, known as pancreatic juice, contains a number of digestive enzymes such as amylase, trypsin, and lipase. The neutralizing function of pancreatic juice is critical because it protects the intestine from the harmful effects of chyme's acidity.


  • Pancreatic amylase is the name of the amylolytic enzyme that can be found in pancreatic juice. Similar to salivary amylase, pancreatic amylase breaks down starch into dextrin and maltose.

  • Pancreatic juice contains two primary proteolytic enzymes: trypsin and chymotrypsin.

  • Additional proteolytic enzymes include carboxypeptidases, elastase, collagenase, and nuclease.

  • Among the lipolytic enzymes present in pancreatic juice are bile salt activated lipase, colipase, phospholipase A, phospholipase B, cholesterol ester hydrolase, and pancreatic lipase.

4. Bile

Bile juice is secreted by liver cells and excreted through the bile canaliculus. For fat to be digested, it must first be emulsified with bile. As a result, it functions as a detergent while also aiding fat absorption. Bile is also used to eliminate bilirubin, a result of red blood cell breakdown.

5. Saliva

Saliva is a digestive juice released by the salivary glands and found in the mouth. It initiates chemical digestion while the mouth is still physically chewing the food. Saliva contains three digesting enzymes:

  • Lingual lipase – A lipid-digesting enzyme. It digests milk lipids, which are pre-emulsified. Lingual lipase hydrolyzes triglycerides to produce fatty acids and diacylglycerol.

  • Salivary amylase - An enzyme that degrades carbs. It works by turning cooked or boiled starch to dextrin and maltose.

  • Maltase - An enzyme that converts maltose to glucose, however it is only present in trace amounts in human saliva.

Digestive Enzymes vs. Probiotics: are they different

Often enzymes and probiotics are confused. Both effect digestion, but in very different ways. Probiotics are live organisms that comprise the beneficial bacteria in your stomach. They serve to maintain your digestive system healthy and hence promote the work of your enzymes. Unlike enzymes, probiotics cannot break down or digest food components.

Without good gut bacteria, you may suffer symptoms similar to those of an enzyme deficiency, such as bloating or gas, as a result of abnormal bacterial overgrowth or imbalance in your intestines.


Keep the digestive track clean; having enough good bacteria and enzyme efficiency can support a healthy and ailment-free you.



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