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The Pancreas: Trypsin, Protein Digestion, and Pancreatitis

The location of the pancreas within the digestive system

The location of the pancreas within the digestive system

The Pancreas and the Function of Trypsin

The pancreas is an important abdominal organ that performs multiple jobs. One of these jobs is to produce digestive enzymes, which enable us to obtain nutrients from food. Trypsin is a potent pancreatic enzyme. It's produced in an inactive form in the pancreas and is activated in the small intestine, where it digests protein. Unfortunately, under certain conditions trypsin is activated within the pancreas, where it may damage tissue and cause pancreatitis.

Digestive enzymes convert the molecules in food into smaller units that our body can absorb. Trypsin converts large and complex protein molecules into smaller and simpler molecules. Other enzymes in the small intestine then complete the digestion of the protein. If a significant amount of active trypsin collects in the pancreas, it may digest the proteins that are a normal part of pancreatic cells, causing potentially serious effects.

Pancreatic islets or islets of Langerhans produce insulin and glucagon. Acinar cells make digestive enzymes.

Pancreatic islets or islets of Langerhans produce insulin and glucagon. Acinar cells make digestive enzymes.

Location and Structure of the Pancreas

The pancreas is a long, narrow, and flat organ on the left side of the upper abdomen (from the owner's point of view). It's located behind the stomach and in front of the spine. The head of the pancreas extends into the curve formed by the duodenum, which is the first part of the small intestine.

The pancreas is an unusual and versatile organ. It contains both endocrine and exocrine glands. An endocrine gland makes a hormone and secretes it into the bloodstream. An exocrine gland secretes its product (which is not a hormone) into a duct. The duct then transports the product to a different area.

Pancreatic hormones are secreted by patches of tissue known as pancreatic islets or islets of Langerhans. Two of these hormones are insulin and glucagon, which play an important role in regulating blood sugar. Digestive enzymes are produced by structures called acini, which are composed of acinar cells. The acini release their enzymes into a fluid known as pancreatic juice. The enzymes include inactive trypsin for digesting proteins, lipase for digesting fats, and pancreatic amylase for digesting starch.

The Pancreatic Duct

Digestive enzymes travel out of the pancreas in a passageway called the pancreatic duct. Cells lining the duct secrete sodium bicarbonate and water into the pancreatic juice. The sodium bicarbonate helps to provide the correct pH for enzyme activity in the small intestine.

The pancreatic duct transports the enzymes to the interior of the duodenum (the first part of the small intestine), where they do their job. Despite the vital role of the pancreas in digestion, food never enters it.

Amino acids are the "building blocks" of proteins. A short chain of amino acids is called a peptide. A longer chain is called a polypeptide. A protein contains one or more polypeptides arranged in a distinct and often complex shape. Enzymes are a type of protein.

This is a ball and stick diagram of an amino acid molecule. The R group is different in each type of amino acid.

This is a ball and stick diagram of an amino acid molecule. The R group is different in each type of amino acid.

Trypsinogen, Trypsin, and Protein Digestion

The inactive form of trypsin is known as trypsinogen. The inactivity is vital, since proteins are very important components of cells. If active trypsin is produced inside pancreatic cells, it will digest the cell's proteins unless it's inactivated or removed.

Even in a healthy person, a very small amount of trypsinogen is converted to trypsin within the acinar cells of the pancreas. There are safeguards in place to reduce trypsin formation and to prevent trypsin from damaging the pancreas, however. For example, trypsinogen is stored in protective, membrane-bound compartments inside the acinar cells. In addition, the acinar cells make chemicals that act as trypsin inhibitors by binding to trypsin molecules and inactivating them. Another important factor is the flow of liquid in the pancreatic duct, which helps to flush activated trypsin out of the pancreas and into the intestine.

When trypsinogen reaches the small intestine, an enzyme called enteropeptidase converts the trypsinogen to trypsin. Enteropeptidase is made by the intestinal lining, or the mucosa.

Trypsin belongs to a class of enzymes known as proteases. These enzymes break down proteins. Trypsin digests proteins from food into shorter peptides. Other enzymes made by the intestinal lining then break the peptides down into individual amino acid molecules. The amino acids are absorbed into the bloodstream through the lining of the small intestine.

In illustration A above, a substrate binds to the active site of an enzyme, is altered, and then leaves as a product. In illustration B, a chemical called a competitive inhibitor binds to the active site of the enzyme, preventing the correct reaction from happening.


Trypsinogen is an enzyme precursor, or a zymogen. It's stored in acinar cells inside membrane-bound sacs called zymogen granules. The word zymogen is derived from the term enzyme generator.

Like all enzymes, trypsinogen has a section called the active site. This is the place where the reactant or substrate of an enzyme-controlled reaction joins to its enzyme. Once this union takes place, a chemical reaction happens and products are produced.

A zymogen such as trypsinogen is inactive because a peptide blocks its active site, preventing it from doing the job of an enzyme. This peptide is removed when the zymogen is activated.

Other zymogens exist in the body in addition to trypsinogen. For example, the pancreas also secretes chymotrypsinogen, which becomes chymotrypsin in the small intestine. Like trypsin, chymotrypsin digests proteins into peptides. Cells in the stomach lining release pepsinogen into the stomach cavity. Pepsinogen is activated by hydrochloric acid, becoming an enzyme called pepsin. Pepsin is a protease. The proteins involved in the blood clotting process are also zymogens. They are activated when we are wounded.

Acute and Chronic Pancreatitis

Rarely, a significant amount of trypsin collects in the pancreas. If the pancreas is unable to inactivate or remove this trypsin, the organ begins to digest itself. As a result, it becomes inflamed, a condition known as pancreatitis.

Pancreatitis may be acute or chronic. Acute pancreatitis arises suddenly and lasts for a short time (provided it's treated). It ranges from a relatively minor problem to a severe or even life-threatening disease. Chronic pancreatitis lasts for a long time or occurs repeatedly. The continuous or repeated damage to the pancreas may lead to the creation of fibrous scar tissue and the loss of function in the organ.

Symptoms of pancreatitis may include:

  • abdominal pain, which may radiate to the back of the body
  • abdominal pain that is worse after eating
  • nausea
  • vomiting
  • fever
  • increased heart rate

In chronic pancreatitis, the stool may become oily. This condition is known as steatorrhea. It develops because lipase, the fat-digesting enzyme made in the pancreas, is no longer reaching the small intestine or is being sent to the intestine in inadequate amounts. As a result, the digestion of fat is greatly decreased. It doesn't stop, however, because lipase is also made in the mouth (lingual lipase) and stomach (gastric lipase). Someone with chronic pancreatitis may find that they lose weight without deliberately trying to do this.

The pancreatic duct joins the common bile duct before sending its secretions into the small intestine. (Bowel is another term for the intestine.)

The pancreatic duct joins the common bile duct before sending its secretions into the small intestine. (Bowel is another term for the intestine.)

The Passage of Bile

The liver produces a liquid called bile, which it sends to the gall bladder. Gallstones may form in the gall bladder or in the ducts that transport the bile. These gallstones may cause pancreatitis.

The passage of bile takes place as follows.

  • The bile leaves the liver in the right and left hepatic ducts.
  • These ducts join to form a single hepatic duct.
  • The bile travels from the hepatic duct to the gall bladder through the cystic duct.
  • Bile is stored in the gall bladder until it's needed to help fat digestion in the small intestine.
  • The bile is sent to the small intestine through the cystic duct and the common bile duct.
  • Some bile is sent directly from the liver to the small intestine through the common bile duct and never enters the gall bladder.

The two main types of gallstones are cholesterol stones and pigment stones. Cholesterol gallstones contain solid cholesterol and other substances. Pigment gallstones contain bilirubin, a yellow pigment.

Gallstones Facts and a Potential Effect

The function of bile is to emulsify fat in the small intestine. During emulsification, fat is broken up into small droplets that are easier for lipase to digest. Bile contains water, bile acids or salts, cholesterol, inorganic salts, and a yellow pigment called bilirubin. Bilirubin is made in the liver from the breakdown of hemoglobin in old red blood cells. The bilirubin is excreted in the bile. Sometimes the dissolved substances in bile are too concentrated and solidify as solid lumps known as gallstones.

The most frequent cause of acute pancreatitis is said to be the presence of gallstones. The common bile duct meets the pancreatic duct before reaching the duodenum. Gallstones transported in the bile duct can become lodged in front of the exit of the pancreatic duct, stopping the flow of pancreatic juice. When this happens, activated trypsin collects in the pancreas and pancreatitis may result.

Other Causes of Pancreatitis

Pancreatitis can be caused not only by blockages in the pancreatic duct but also by the increased conversion of trypsinogen to trypsin within the pancreas and the decreased destruction of the trypsin that forms. Factors that may trigger trypsin formation include an increase in calcium concentration within the acinar cells and changes in pH. Mitochondrial damage may also play a role in triggering pancreatitis. The mitochondria are the organelles that produce energy for a cell.

Alcoholism is a common cause of the disorder. In some places, the number of people with pancreatitis linked to alcohol consumption is increasing. The repeated ingestion of alcohol increases the amount of trypsin in the pancreas, although how it does this is not yet understood.

Less common causes of pancreatitis include an abnormally high blood level of fats (hypertriglyceridemia) or calcium (hypercalcemia). Injury to the pancreas, some infections, and certain autoimmune conditions can also trigger the disorder. Some medications have been implicated in the disease as well. Sometimes the cause of the disorder is never discovered, and the condition is said to be idiopathic.

Some Comment Treatments

A person with pancreatitis needs to be under a doctor's care. The doctor will diagnose the disease and prescribe appropriate treatment. The initial treatment often involves medication to relieve pain and procedures to help the pancreas heal itself, which may include temporary fasting and the administration of intravenous fluids.

Once the inflammation in the pancreas has subsided or is reduced, doctors generally try to correct or compensate for the condition that caused the pancreatitis. Gallstones may be removed, for example, or digestive enzymes prescribed. Dietary changes may be recommended and the patient may be given help to eliminate alcohol dependence. Occasionally, surgery may be necessary to remove fluid from the pancreas or to remove damaged tissue.

Investigating Pancreas Problems

Alcoholism is the second most common cause of pancreatitis. Despite this fact and the fact that many scientists are investigating pancreatitis, we don't know how alcohol causes the disease. In fact, there are many unanswered questions about pancreatitis that develops from any cause.

We still have a lot to learn about the pancreas and its activity. Studying the operation of the organ is an important endeavour because of the many ways in which it affects our lives. It would be wonderful to be able to correct pancreas problems both easily and quickly.


This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

Questions & Answers

Question: Where are amino acids formed in the human body?

Answer: The nonessential amino acids (the ones that we can make in our bodies) are manufactured in cells as a result of chemical reactions involving various reactants.

© 2015 Linda Crampton


Linda Crampton (author) from British Columbia, Canada on April 17, 2020:

Thank you for the comment.

V on April 17, 2020:


Linda Crampton (author) from British Columbia, Canada on May 05, 2016:

What a horrible and frightening situation for your friend! I'm glad the true nature of her situation was eventually realized. Thank you for the comment and the share, RTalloni.

RTalloni on May 05, 2016:

Your work is always interesting and useful. Someone I know had gallbladder surgery but blockage in the pancreas was missed so she eventually wound up having a second surgery.

On first returning to the ER due to the pain she was told to go home because pain after gallbladder surgery was to be expected. That response to her situation nearly cost her life. It seems quite simple that they should've put two and two together very quickly in such a case, but I now know this happens surprisingly often.

It seems that this should not be necessary, but if a patient like that read your information ahead of time it's possible they could help health care professionals get to a correct diagnosis more quickly. I'm glad to have read it and to be able to share it with others because mistakes in hospitals are on the rise.

Linda Crampton (author) from British Columbia, Canada on August 07, 2015:

Thank you very much for the comment, word55. I appreciate your visit. Blessings to you!

Al Wordlaw from Chicago on August 07, 2015:

Hi AliciaC, this was very educational. I love learning the functions of the human body and why some may go bad. Thank you for the research, videos and commitment to dispensing anatomic knowledge. It is so good to know the importance/function of every organ in our body system. God bless you so!

Linda Crampton (author) from British Columbia, Canada on July 12, 2015:

Hi, adevwriting. Yes, biology is fascinating! Thanks for the comment.

Arun Dev from United Countries of the World on July 12, 2015:

Biology is an amazing science! This hub was a simple and an informative way to explain about pancreatic enzymes. Keep up the good work!

Linda Crampton (author) from British Columbia, Canada on June 05, 2015:

I'm constantly amazed by the workings of the human body, too, Deb! Thank you for the comment.

Deb Hirt from Stillwater, OK on June 05, 2015:

This tiny organ is truly remarkable. It never ceases to amaze me how the body can be such a wonderful, smoothly operating machine. Thanks for the great info!

Linda Crampton (author) from British Columbia, Canada on May 27, 2015:

Thank you very much for the lovely comment, Nadine.

Nadine May from Cape Town, Western Cape, South Africa on May 27, 2015:

This was a very informative and easy to read hub Alicia. Loved the diagrams and videos and learned a lot.

Linda Crampton (author) from British Columbia, Canada on May 09, 2015:

Thank you very much for the kind comment, Vellur.

Nithya Venkat from Dubai on May 09, 2015:

Great hub with a treasure trove of information about the digestive enzymes from the pancreas. Useful and informative. Voted up.

Linda Crampton (author) from British Columbia, Canada on May 06, 2015:

Thank you very much, Bill. I appreciate your comment a great deal.

Bill De Giulio from Massachusetts on May 06, 2015:

Great job Linda. Certainly an education for those of us with a limited knowledge of how the human body works. Great presentation, explained clearly so even I could follow.

Linda Crampton (author) from British Columbia, Canada on May 05, 2015:

Hi, torrilynn. Thanks for the comment. I hope you did well in your test even though you got one answer wrong!

torrilynn on May 05, 2015:

thanks for this hub it was useful indeed. i just had a test on this today in my anatomy class and sadly i got the answer wrong about the pancreas and what it does. anywho, thanks for the read.

Linda Crampton (author) from British Columbia, Canada on May 03, 2015:

I'm sorry about your gallstone, Audrey. Thank you for the comment about the hub. I appreciate the votes and the share, too!

Audrey Hunt from Pahrump NV on May 03, 2015:

I so appreciate learning more about gallstones. I have a large one and have been told that it is too big to pass, so will just live with it. Alicia, this hub is informative and interesting with much research put into it.

I voted up, useful, awesome, interesting and will certainly share.

Linda Crampton (author) from British Columbia, Canada on May 03, 2015:

Hi, Faith. Thank you for the comment, the votes and the shares. Pancreatic cancer can be a very serious condition. I hope better ways of treating it are discovered soon.

I hope the rest of Sunday is very pleasant for you.

Faith Reaper from southern USA on May 03, 2015:

Our bodies are fascinating in all that they do no doubt. Your hubs are always informative and useful and written so well that is easily understood by the reader. Thank you for that! I am thinking of pancreatic cancer which is so devastating and how they usually discover it by accident or way too late.

Voted up +++ tweeting, pinning, G+ and sharing

I hope you are enjoying a peaceful Sunday.

Linda Crampton (author) from British Columbia, Canada on May 01, 2015:

Hi, alexadry. Thanks for commenting and for sharing the interesting information. I had a yellow lab who had pancreatitis. Thankfully she recovered well once she was diagnosed with the disease and treated.

Adrienne Farricelli on May 01, 2015:

This is very interesting, I love learning how our bodies work. Even dogs get pancreatitis and need temporary fasting. When doing rounds in the vet's office, I used to stumble the miserable doggies and the word NPO was written on the cage, meaning they couldn't be fed anything!

Linda Crampton (author) from British Columbia, Canada on May 01, 2015:

Thank you very much for such a kind comment, drbj!

drbj and sherry from south Florida on May 01, 2015:

You have a knack, Alicia, for making a subject both fascinating and interesting for the reader. This was an outstanding example via your matter-of-fact prose and excellent, illustrative diagrams. Thank you.

Linda Crampton (author) from British Columbia, Canada on May 01, 2015:

Thank you very much for the kind comment and the votes, Flourish!

FlourishAnyway from USA on May 01, 2015:

This is very thorough and well presented. I knew little about the topics previously and you did an excellent job explaining! Voted up and more.

Linda Crampton (author) from British Columbia, Canada on May 01, 2015:

Thanks, Larry. I always appreciate your visits and comments.

Linda Crampton (author) from British Columbia, Canada on May 01, 2015:

Thank you very much, yograj yog! I appreciate your kind comment a great deal.

Larry Rankin from Oklahoma on May 01, 2015:

Fascinating analysis.

Yogesh Oza from Ahmedabad, Gujarat, INDIA. on May 01, 2015:

A wonderful hub! Amazing word,"Pancreatitis"!

The videos and pictures included are very illustrative and helping. The

information is very useful.

How interesting as well as shocking it is to know that the enzyme,

which digests protein of food for our benefit, can digest even protein of our internal organ to damage us!

How wonderful it is that inactivity of trypsin is vital in pancreas; but it's activity is vital in small intestine!

Thank you AliciaC, for giving such a helpful information. Thanks.

Linda Crampton (author) from British Columbia, Canada on April 30, 2015:

Thank you, Jackie. Human biology is a fascinating topic to study.

Jackie Lynnley from the beautiful south on April 30, 2015:

So very interesting; really a miracle in one way of looking at it. So complex and yet so natural.

Linda Crampton (author) from British Columbia, Canada on April 30, 2015:

Thank you so much for the comment, ologsinquito. I agree - the human body is amazing!

ologsinquito from USA on April 30, 2015:

What a great article and so detailed. The human body really is amazing.

Linda Crampton (author) from British Columbia, Canada on April 30, 2015:

Hi, MsDora. Thank you very much for the comment and the vote. I appreciate your visit. Some pancreatic diseases are very dangerous and are life threatening. Pancreatitis can certainly be very serious, but sometimes it is less so.

Dora Weithers from The Caribbean on April 30, 2015:

I have heard that pancreatic diseases are mostly fatal; could it be because of our ignorance about symptoms etc? The facts you relate about this organ and it process are so important but not popular. An important lesson, effectively outlined. Voted Up!

Linda Crampton (author) from British Columbia, Canada on April 30, 2015:

Hi, kj force. Thanks for the comment. The state of food today is certainly worrying. So many people rely on processed foods for much of their diet. Even natural foods have often been altered in some way. There's a lot to think about when going to a grocery store!

kjforce from Florida on April 30, 2015:

AliciaC 2....Well written and researched kudos...

And people wonder why Type 2 Diabetes is so prevalent in today's society. Since WWII processed and chemically altered foods have been a large part of our diets, damaging organs and now we deal with GMO foods. It is dually noted that added chemicals and un-natural elemenys entering the body's system will compromise it's natural function and immune-system...Scientist have recently stated after a 20 year study.." Antibiotics ( in animal meat ,chickens and their feed ) are creating health issues in the Human body and should be me a no brainer....thanks for sharing

Linda Crampton (author) from British Columbia, Canada on April 30, 2015:

Thank you very much, Bill. I appreciate your comment!

Bill Holland from Olympia, WA on April 30, 2015:

Where were you when I had anatomy in school? I could have used your practical way of explaining things. Well done once again.