What is the Difference Between Gastric Juice and Pancreatic Juice

The main difference between gastric juice and pancreatic juice is that the gastric juice mainly contains enzymes for the digestion of proteins whereas the pancreatic juice mainly contains enzymes for the digestion of carbohydrates and fat. Furthermore, gastric juice is acidic while pancreatic juice is alkaline.

Gastric juice and pancreatic juice are the two main types of secretions in the digestive system, containing digestive enzymes. The stomach secretes gastric juice while the pancreas secretes pancreatic juice to the jejunum of the small intestine.

Key Areas Covered

1. What is Gastric Juice
     – Definition, Components, Type of Digestion
2. What is Pancreatic Juice
     – Definition, Components, Type of Digestion
3. What are the Similarities Between Gastric Juice and Pancreatic Juice
     – Outline of Common Features
4. What is the Difference Between Gastric Juice and Pancreatic Juice
     – Comparison of Key Differences

Key Terms

Carbohydrate Digestion, Fat Digestion, Gastric Juice, Pancreas, Pancreatic Juice, Protein Digestion, Stomach

What is Gastric Juice

Gastric juice is a thin, clear, virtually colorless acid fluid secreted by the stomach glands. These glands extend deep to the mucosa of the stomach wall. It mainly contains digestive enzyme responsible for the chemical digestion of proteins. The exposure of food to the gastric juice produces a semi-liquid mixture called the chyme. The main components of the gastric juice are hydrochloric acid, pepsin, intrinsic factor, mucus, and water.

• Hydrochloric acid – responsible for the acidic pH of the gastric juice. The pH of gastric juice is around 1-2. Parietal cells located at the middle of the gastric glands produce and secrete HCl. The acidic pH destroys pathogens that enter into the stomach along with food.
• Pepsin – the enzyme responsible for the digestion of proteins into small peptides. It is secreted in the inactive form as pepsinogen by chief cells located at the bottom of the gastric glands and HCl converts pepsinogen into pepsin. In addition, the HCl denatures the proteins in food, facilitating digestion. The HCl provides the optimal pH required by the enzymatic action of pepsin as well.
• Intrinsic factor – secreted by parietal cells. It is responsible for the protection and the absorption of vitamin B12.
• Mucus – lubricates the chyme. It also protects the lining of the stomach from the acidic pH.
• Water – dilutes food particles, facilitating both mixing and digestion. It is produced by the mucous neck cells near the opening of the gastric glands.
  

  Figure 1: Major Digestive Enzymes

Furthermore, both neuronal and hormonal stimuli regulate the secretion of gastric juice. Parasympathetic nervous system stimulates the secretion of gastric juice in response to the sight or smell of food. On the other hand, gastrin is the hormone that increases the secretion of gastric juice from the stomach. It is secreted by the stomach itself.

What is Pancreatic Juice

Pancreatic juice is the clear, alkaline digestive fluid secreted by the pancreas. Pancreas also serves as an endocrine gland by secreting hormones. Most of the enzymes in the pancreatic juice, including trypsinogen, chymotrypsinogen, procarboxypeptidases, and proelastase, are secreted in the inactive form. Apart from that, pancreatic juice includes amylase, lipase, nuclease, and bicarbonate ions. The main function of pancreatic juice is to digest carbohydrates and fat in food.

• Bicarbonate – responsible for neutralizing the acidic pH of the chyme. Both bile and small intestinal juice aid in this neutralization. Moreover, the pH of the food in the small intestine is 8 and it provides the optimal conditions for the functioning of the pancreatic enzymes.
• Trypsin– the main type of enzyme found in the pancreatic juice. It is responsible for the digestion of proteins into polypeptides. Trypsinogen is the inactive form secreted by the pancreas while Enteropeptidase, located in the brush border of the jejunal mucosa, is responsible for the convertion of trypsinogen to trypsin. Then, trypsin activates all of the other inactive enzymes. Moreover, Chymotrypsin is another enzyme responsible for the protein digestion, which is activated by trypsin.
• Pancreatic amylase – responsible for the digestion of the starch into maltose.
• Pancreatic lipase – responsible for the digestion of the triglycerides into glycerol and fatty acids.
• Prophospholipase, activated to phospholipase – responsible for the digestion of phospholipids.
• Cholesteryl ester hydrolase – responsible for the digestion of cholesteryl esters.
• Deoxyribonucleases and ribonucleases – responsible for the digestion of DNA and RNA respectively into mononucleotides.
  

  Figure 2: Hormonal Regulation of Digestive Enzyme Secretion

Furthermore, several regulatory peptides and neurotransmitters secreted by the intestine, pancreas, and the vagus nerve are responsible for the regulation of the pancreatic secretions. Some of them include Secretin, CCK (cholecystokinin), neurotensin, motilin, PYY and pancreatic islet hormones including insulin, pancreatic polypeptide and somatostatin.

Similarities Between Gastric Juice and Pancreatic Juice

• Gastric juice and pancreatic juice are the two main types of secretions with digestive enzymes in the digestive system.
• Both are exocrine glands.
• Also, both contain water, mucus, digestive enzymes, salts, and ions.
• In addition, both are responsible for the chemical digestion of food.
• Moreover, different hormones as well as nerve inputs stimulate the secretion of both juices.

Difference Between Gastric Juice and Pancreatic Juice

Definition

Gastric juice refers to a thin, clear, virtually colorless acid fluid secreted by the stomach glands and active in promoting digestion while pancreatic juice refers to the clear, alkaline digestive fluid secreted by the pancreas. Thus, this explains the basic difference between gastric juice and pancreatic juice.

Glands

Gastric glands secrete gastric juice while exocrine glands secrete pancreatic juice.

pH

Another difference between gastric juice and pancreatic juice is that gastric juice is acidic while pancreatic juice is alkaline.

Components

The components each juice contain is also an important difference between gastric juice and pancreatic juice. Gastric juice contains pepsin, hydrochloric acid, intrinsic factor, mucus, and water while pancreatic juice contains bicarbonate, trypsinogen, chymotrypsinogen, elastase, carboxypeptidase, pancreatic lipase, nucleases, and amylase.

Main Role

The main role of the gastric juice is to digest proteins while the main role of pancreatic juice is to digest carbohydrates and fat. This is a major difference between gastric juice and pancreatic juice.

Stimulation

Stimulation is another difference between gastric juice and pancreatic juice. A hormone called gastrin stimulates the secretion of the gastric juice while hormones called secretin and pancreozymin stimulate the secretion of the pancreatic juice.

Conclusion

Gastric juice is the secretions of the gastric glands in the stomach. It is acidic and the digestive enzymes in the gastric juice are responsible for the protein digestion. On the other hand, pancreatic juice is the secretion of the pancreas into the jejunum of the small intestine. The digestive enzymes in the pancreatic juice are responsible for the digestion of carbohydrates and fat. Therefore, the main difference between gastric juice and pancreatic juice is the pH and the type of digestive enzymes in each type of secretion.

Reference:

1. “The Stomach and The Pancreas.” Lumen|Boundless Anatomy and Physiology, Available Here
2. “Pancreatic Juice.” Pancreatic Juice – an Overview | ScienceDirect Topics, Available Here

Image Courtesy:

1. “Major digestive enzymes” By No machine-readable author provided. Stephaniegreenwood assumed (based on copyright claims). – No machine-readable source provided. Own work assumed (based on copyright claims). (Public Domain) via Commons Wikimedia  
2. “Digestive hormones” By Tekks at English Wikipedia (CC BY-SA 3.0) via Commons Wikimedia