Back To CoursePathophysiology Textbook
20 chapters | 274 lessons
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When I was in undergrad, I used to load big trucks every day for a shipping company in order to support myself. Every now and then, dangerous packages would be shipped right alongside your very own X-Box. If the chemicals in those packages were exposed to fluid, or air, or another chemical, they could set on fire, explode, or release toxic fumes. That's why a whole series of steps were taken in order to ensure that this did not happen. Thankfully for me, it never did.
Some of your body's organs perform the exact same task, safety through numerous measures, in order to try and ensure that you are kept safe from your own self. It sounds weird, I know. But this lesson will explain how that is the case.
In your body lies an organ that is near the stomach and right by the duodenum, the first part of the small intestines that connects to the stomach, called the pancreas. This organ produces insulin, a hormone that helps to lower blood sugar. It also produces digestive enzymes, which are proteins that speed up chemical reactions. The enzymes produced by the pancreas are called proteases, lipases, and amylases. They help to digest proteins, lipids (aka fats), and carbohydrates, respectively.
Your pancreas is, therefore, mainly concerned with producing these exocrine enzymes, much more so than it is concerned with producing the endocrine hormones, such as insulin. I'm sure you are aware by now that food manufacturers use all sorts of chemicals to help tenderize, break down, or even completely transform food. That's what the pancreas does - it makes proteins that do the same things naturally.
When it comes down to the proteases, the pancreas first produces an inactive enzyme precursor called a zymogen, or proenzyme. The inactive and therefore harmless enzyme precursors (our zymogens) are stored in a secretory vesicle, a balloon-like thing called a zymogen granule. The physical encapsulation of the zymogens by a zymogen granule further ensures the safety of our body away from these digestive enzymes. The zymogen granules are like a gun safe for our unloaded guns, the proenzymes.
What's more is that the zymogen granules contain an acidic environment, or low pH, which further ensures the inactivation of these enzyme precursors, since they actually need a more basic environment, such as the one found in the duodenum, to perform their roles during digestion. Therefore, this acidic environment is like an additional combination lock on the gun safe. It's just added protection.
These zymogens are secreted by the acinar cells into the pancreatic duct and out into the small intestine. Here, bile, which is produced in the liver and stored and secreted by the gallbladder, forces an enzyme, called enterokinase, off of the brush border cells lining the duodenum. The enterokinase activates a proenzyme, called trypsinogen, that has been secreted out by the pancreas. Trypsinogen is then converted into a protease made by the pancreas, called trypsin. It is trypsin that goes on to activate all the other proteases from their proenzyme precursor forms.
Therefore, these previous steps are akin to the gun safe being opened, the guns being loaded, and from there on being used to fire away at the incoming particles of food.
Now, by no means have I given you the full picture of what actually occurs. We don't have time for that right now, but you at least have enough information for a very good appreciation of what I'm about to tell you.
If these and other protective measures I outlined for you are compromised for any reason, the proenzymes are activated within the pancreas itself. This means that the pancreas begins to digest itself using its own proteases! These enzymes then begin to break down the pancreas and trigger inflammation of the pancreas, aka pancreatitis.
This inflammatory process further recruits immune cells, such as neutrophils, to the pancreas. They release even more degradative enzymes to cause even further inflammation and destruction of the pancreas. It's like a tag-team wrestling match where a bunch of wrestlers gang up on a little guy.
This inflammation in acute pancreatitis, which is pancreatitis of severe and sudden onset, causes vomiting and a lot of pain; plus, it causes the pancreas to bleed and swell. The pancreas begins to die if this process isn't controlled, and the release of toxins, inflammatory mediators, and enzymes not only begins to destroy the pancreas but surrounding organs, such as the liver, and may even lead to respiratory distress, septicemia, and systemic shock. Wow! It's as if that one hazardous package at the back of the truck I was loading exploded and set all the other packages on fire! That's what may happen in acute pancreatitis.
In cases of chronic, or long term, pancreatitis, the pancreas has large areas that are destroyed, non-functional, and filled with scar tissue.
In either case, biliary tract disease that blocks the outflow of pancreatic juices and alcohol consumption are two major factors leading to pancreatitis. But anything from physical trauma to autoimmune disease can cause the same problems.
Pancreatitis will, not surprisingly, reveal elevated levels of lipase, amylase, and trypsin. Improper digestion as a result of pancreatitis may reveal elevated levels of fat in the stool. Liver enzymes levels may be increased if the liver is damaged or if biliary tract issues are suspected. Imaging exams via ultrasound or CT scans can reveal further signs of pancreatitis or its cause, such as gallstones.
Treatment, depending on the extent and severity, can be any combination of pain control, antibiotics for secondary infections, nutritional support and modification, as well as surgery.
I hope this lesson scared you a little bit. Messing with the pancreas is one of the worst things you can do to yourself. As if I didn't warn you in other lessons enough about stopping alcohol consumption, do it for the sake of your pancreas!
Remember that the pancreas first produces an inactive enzyme precursor called a zymogen, or proenzyme. These inactive and therefore harmless enzyme precursors (our zymogens) are stored in a secretory vesicle, a balloon-like thing called a zymogen granule.
One of these proenzymes is trypsinogen, and it is converted into a protease made by the pancreas, called trypsin, in the gut. It is trypsin that goes on to activate all the other proteases from their proenzyme precursor forms.
If these enzymes are activated prematurely in the pancreas, they begin to break down the pancreas and trigger inflammation of the pancreas, also known as pancreatitis.
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Back To CoursePathophysiology Textbook
20 chapters | 274 lessons